2015 MSU-500 crank - no start

[Prepper]

I'm working with a 2015 MSU-500.  Basic symptoms are it cranks well, but will not fire.  It has spark, and it has fuel spraying out of the injector (and spraying starting fluid into the throttle body and plug hole makes no difference).  It has compression.  I bought it not running, and no other information was available.  It has 775 miles on it and 127 hours.  It looks to be in very good shape.   Previous owner replaced fuel pump, ECU, coil, plug, and the fuse/relay box that mounts on the firewall, then gave up.

My questions relate to cam/valve timing, considering the symptoms and diagnostics so far.  My thinking was the woodruff key sheared off and the crank spun, making it out of time.  My question is, by the pictures attached does anyone have an opinion as to the cam/valve timing being correct?  In the crankshaft picture you can see a timing mark visible.  In the camshaft picture I have arrows directed towards what I think are timing marks (which appear to be exactly 180 degrees from one another).  However, the long arrow in what appears to be bolt configuration in line with the piston/rod line.  Here is a puzzling note... in the position you see in the pictures... I have valve lash on both the intake and exhaust.  I think it's at TDC, given the visible crank timing mark and valve lash on both valves. 

Any thoughts ?  Does this appear to be in proper valve time ?  Have I missed anything simple ?  Thanks in advance for your input.

[motojoe]

On your picture I see camshaft gear and marks but on the head there should be marks to time the camshaft to.  Unless that grease mark on the top of the picture is a timing mark your are out of time by at least 40 degrees.  Find the timing marks on the head and line up the camshaft timing marks.

[Prepper]

49 minutes ago, motojoe said:

On your picture I see camshaft gear and marks but on the head there should be marks to time the camshaft to.  Unless that grease mark on the top of the picture is a timing mark your are out of time by at least 40 degrees.  Find the timing marks on the head and line up the camshaft timing marks.

Yes, the grease mark is actually a point in the cast of the head.  I was just confused because I couldn't see a customary dimple mark in the cam gear itself.  I did pull off the head today because I saw one of the cam lobes appear to be severely worn.  When I pulled the cam out sure enough the exhaust lobe was severely worn.  I couldn't see a way to get the rocker arms out, they appear to be unserviceable.   I'm ordering a completely new head.  Although my original post was about a no start condition,  I doubt a worn exhaust lobe would keep it from starting. 

[Ben1098]

 

BTW.......rocker shafts are removed by screwing in an 8mm??? bolt and then pulling on the bolt head and/or slide hammer.  Rockers are then removed.

You first need to check the possible sheared crankshaft key.  Take a soft copper wire about 16" long and put a finger loop on one end.  Stick the wire into the spark plug hole and rest on the piston dome.......slowly rotate the engine.  The TDC on the crank should align when the copper wire is at it's highest point and will fall back from it's peak as you rotate back and forth at the TDC mark.  I like to dab some paint on the crank to make the mark easily spotted when doing any timing jobs.  Compare to the first pic.  Leave at TDC.

NOTE:  There are 2 TDC with a 4 stroke engine.......720 deg of rotation.  The position of the cam at TDC will determined if it is OVERLAP or compression/IGNITION/power .  This has caught many a person on V-Twin engines that will run BUT be low power and the wrong exhaust note.  Both cams are "TDC" and fire OK but they are not "phased" correctly.   Short and Loooong intervals between the front and rear cylinders power strokes.....gives a lumpy sound.  Yours is a single cylinder.

Your timing was correct or off by one tooth.  Your pic is shot at an angle so hard to tell.  When you are putting the new head and cam on, inspect the cam assy.  Get a good look at the cam and the compression release "mini cam".  Slide in the cam with the lobes AWAY from the rocker slipper pads.

REF your pic above........The longest RED ARROW aligns with the cam mounting bolt(s) and the cam gear punch mark which is hidden when assembled. It is UNDER one  of those  stamped thin step folded metal "keeper" for the flyweights.  When the flyweights sling out with engine RPM rotation, it will turn the smaller round disc by way of the dual connecting pins.  The cam gear timing mark (dimple) is under the upper (in your pic) keeper close to the teeth.  Right below this bolt is the timing mark for the compression release mini cam.....the quarter sized CENTER disc in your pic.  It is just barely showing (about half of the dimple circle) adjacent to the RH side of your RED ARROW.  This dimple should align with the cam gear dimple....NOTE:  It can be put in 180 deg out relative to the valve cam.  I always put a dab of white paint on the cam gear timing mark with a little smear almost up to the teeth (on the machined rim) so you can see the timing mark AFTER the keepers are installed under the cam mounting bolts.

Timing alignment:

(1)    TDC mark on the flywheel at case mark WITH the slack taken out of the tensioner side of the cam chain (no tensioner installed yet) along with                                (2)    cam gear paint mark  AND  and the dimple in the center disk (compression release mechanism).  Install tensioner and "hand" crank (turn over) the crank to ckeck for binds.

Special note to NOT adjust the valve clearance when the cam is on the compression release ball.  Hand turn the crank to the TDC and at slow RPM (as in hand crank) the flyweights will be pulled in with the springs (the compression release is active and holding the exhaust valve slightly open with a small ball under the exhaust rocker.........will give the wrong valve adjustment.  Continue turning in the direction of rotation until the ball clears the rocker (recess back into the hollow cam center).  Finger tighten the adjustment screw to ZERO clearance and reverse the rotation.  When the compression release ball starts to get under the cam, it will "lock up the flyweights".  Manually rotate the flyweights to the extended rotation (RUN) position and your should be able to reverse the motor/cam even more.  When close to TDC, adjust to spec clearance.

The extra step above seems to be extra and not needed but what you are looking for is a bad batch of compression release cams....... the flyweights did not collapse to the fully closed position.  I had these cam problems also in the Yam Rhino (identical weight tab welds and tooling cuts (same OEM???) and my modified cam (my personal shelf stock) given away to fix a Rhino.  My modification was the grind the excess material on the welded on tab to give the rest of the clearance at where it rubbed the compression release "quarter sized " disc.

Covered in an earlier BEN 1098 post.

 

[Prepper]

Wow Ben... thanks for the comprehensive explanation.  Thanks for taking the time, as you will have saved many the time and frustration in getting the engine timed correctly.

[Prepper]

Hello Everyone...

I am still trying to get this thing started.  Since my initial post, I have replaced the complete cylinder head.  I decided to replace the complete head because the exhaust lobe on the camshaft was badly worn.  While I didn't think this would cure the no-start issue, the cam needed to be replaced along with the rockers and other related parts.  I have attached 2 videos of the issue.  The "spark" video, I think, may be the reason the engine is not firing correctly.  This is a weird, in that I think the plug is firing TOO MUCH.  The flywheel looks good (pictures included) but the question I have is... what on the flywheel tells the ECU that the engine is at TDC to fire the plug and detonate the air/fuel mixture ?  Is it (what I will call the "dimple"), or is it the space in the line of magnets ?  Since the wires attached to the pick-up sensor on the stator assembly/housing didn't look in the best shape, I have a new stator assembly on the way.  But I'm wondering if I should replace the flywheel also.  If the picture, if the "dimple" is actually a spot where a magnet fell off, that would certainly cause a problem.  But again, I see the spark problem (inconsistency) an issue.  Any thoughts ???

[motojoe]

Yes I would replace the flywheel if the magnet is no longer there.  The pick-up coil on the stator when the magnet on the flywheel pass it give out a electric pulse and also determines the engine timing the ecu if there an issue with the timing then I would check the key way on the flywheel.  Second I would check the camshaft timing to flywheel to determine that your valve timing is correct.

[Prepper]

29 minutes ago, motojoe said:

Yes I would replace the flywheel if the magnet is no longer there.  The pick-up coil on the stator when the magnet on the flywheel pass it give out a electric pulse and also determines the engine timing the ecu if there an issue with the timing then I would check the key way on the flywheel.  Second I would check the camshaft timing to flywheel to determine that your valve timing is correct.

I hate to replace the flywheel if there is noting wrong with it.  Would you, or anyone, have a picture of that magnet (if there is one supposed to be there) ?  I checked the pictures online on the sales sites and none of them show that section of the flywheel.  I would like to verify if indeed mine threw a magnet or not.

[Ben1098]

Your pics are of the outer rim of the flywheel.  The tabs in your pics are for the pick up coil......ECU senses the + and - pulses as the square buttons pass under the "face" of the PU coil.  You have a "Missing Pulse" set up here.  Others machines, like 4 wheelers, will only have a Single tab for a single cylinder and a V engine will have 2 with it's marks line up for  IT'S  TDC when they pass under the coil face.  The pick up  coil has a round bar magnet inside and wire wound around the bar magnet.  Take the PU coil and put a small blade screw driver on the face...feel the pull of the PU coil internal magnet.

MAGNETS  Not shown in your  pictures.......they are on the inside of the flywheel.  They will be blocks (sometimes glued to the inside walls.  Some had failures with unbonding but it will destroy the stator knuckles......these are used for charging the battery using the regulator....3 Phase......thus, these are the  3  yellow (white) wires that go to the Regulator.  These have nothing to do with the timing tabs on the outer rim.  Test the magnet(s) inside by taking say a 3/8" extension and roll around the inside.....will pull/stick at the gaps in the magnet bodies.  You can see if the bonding has a crack.

[Prepper]

7 hours ago, Ben1098 said:

Your pics are of the outer rim of the flywheel.  The tabs in your pics are for the pick up coil......ECU senses the + and - pulses as the square buttons pass under the "face" of the PU coil.  You have a "Missing Pulse" set up here.  Others machines, like 4 wheelers, will only have a Single tab for a single cylinder and a V engine will have 2 with it's marks line up for  IT'S  TDC when they pass under the coil face.  The pick up  coil has a round bar magnet inside and wire wound around the bar magnet.  Take the PU coil and put a small blade screw driver on the face...feel the pull of the PU coil internal magnet.

MAGNETS  Not shown in your  pictures.......they are on the inside of the flywheel.  They will be blocks (sometimes glued to the inside walls.  Some had failures with unbonding but it will destroy the stator knuckles......these are used for charging the battery using the regulator....3 Phase......thus, these are the  3  yellow (white) wires that go to the Regulator.  These have nothing to do with the timing tabs on the outer rim.  Test the magnet(s) inside by taking say a 3/8" extension and roll around the inside.....will pull/stick at the gaps in the magnet bodies.  You can see if the bonding has a crack.

Thanks Ben...  When rolling the extension on the inside of the flywheel, I can feel the pull/push sensation you speak of.  It's the same for ALL areas of the inside surface, so I assume the inner magnets are working correctly to generate a power sufficient to charge the battery (although I am more concerned with getting the thing running at this point).  When placing a flat-head screw driver tip on the outer magnets I can feel some stickiness, but only slight and not as strong as the inside.  I also placed the screw driver on the pickup coil and that has stickiness also.  I tested the ohms reading across the two wires coming from the pickup coil and that registered 232.2.  I was unable to find the correct specs reading anywhere on that, but it doesn't really make a difference because I have a new stator arriving tomorrow.  I will check the new one and compare the two.  

At this point I am struggling to find something that would explain the erratic spark display that can be seen in my spark video above.  I don't think what is being exhibited in that video is correct.  My thoughts are that maybe the plug is firing on the power side of the compression stroke, and/or maybe firing on the exhaust stroke to cause the popping out the exhaust.  It's obviously getting fuel or there could be no popping out the exhaust.  I truly believe the valve timing and lash is as close to perfect as a human can get it.  However, if the new stator/pickup coil combo doesn't cure the issue than I'm at a loss for an explanation of the erratic spark.  The ECU is new, the coil is new, and the plug and wire are new, and the connectors to the ECU all look good.  I guess the new ECU could be faulty, but so could the next one I buy also, so I am not inclined to purchase a new ECU at this point (as it is making spark to the plug).  If the new stator combo doesn't cure the no-start issue, then I think the only next step to try is to purposely move the cam timing on or two teeth each way and see if that makes any difference.  

I appreciate your replies !

[Prepper]

Hello Everyone...

Still in a no-start condition.  After replacing the stator/pickup coil, spark looks much better (stronger and more uniform).  I can now here some detonation in occasional cranks, to the point of exhaust flange getting warm to the touch.  I have attached some pictures of the current cam position.  I have verified TDC by both piston travel, and TDC timing line on the flywheel in the timing window.  In this cam position I have valve lash (.004 intake and .006 exhaust).  I have verified fuel spraying out the injector.  Compression still at 145psi.  Anyone have any thoughts on if the cam timing looks correct?  Keep in mind of the difficult angle to get a full frontal shot.

Thanks...

[Ben1098]

The inner bonded magnets are for the charging system.  Nothing to do with the ignition unless the AC signal is used as a check by ECM to see if the engine is rotating.

The outer metal tabs are just that....metal (steel) tabs for the pick up coil's internal magnet.  Think of the keeper bar for a kids toy horseshoe magnet.  The steel tabs react with the magnet inside the coil...sorta a make break for the magnetic flux..  The changing magnetic flux (starting with a change at the leading edge and a reverse at the trailing edge) generate the + and - pulse spikes.  Your screw driver has some residual magnetism....it will probably pick up small screws. Try another tool.

The ignition is a wasted spark system.  The crank turn over 2 times per full stroke......since it doesn't have a cam sensor, just like an B & S lawnmower engine with points just run of the crankshaft....spark every rotation of the crank.....be it COMPRESSION or EXHAUST.  Spin over with a timing light and check the painted timing mark (close to TDC).

Coil resistance is in the ball park.  At least it is not an open circuit.

My old computer video player cannot play your videos....my bad I guess.  I cannot view for a guess what is going on.

Only set the timing marks per earlier reply.  They will run a couple of teeth off, but poorly.

You written description makes me think the exhaust valve is not adjusted correctly.  This can happen if the valve was adjusted on the compression release button location....... and was out.  This will result in the valve adjustment being wrong.  Turn the engine over slowly by hand and bring the piston to TDC on Compression (both valves closed).  Check for valve clearance.  The decompression pin will be holding the valve slightly open.  Turn backwards and feel for the valve to close again....this takes the load off the decompression cam actuator.  Push the flyweights on the cam to the run position (rotates the small dime sized inner disk) and hold open while rotating to TDC AGAIN.  This is what happens after the cranking speed increases after firing up and rotating to the idle speed.  Check your clearance at the TDC this time.  Adj if off.  If you release the flyweights, they will sorta "stay" in the open position.  The flyweight springs cannot physically push the exhaust valve open for decompression.  There is a small inner cam that pushes the actual pin out before the valve rocker hits this decompression pin.  Slowly rotate the engine backwards and the flyweights will fully retract.  Slowly rotate forward and the exhaust halve will slightly open this time......lowering the compression pressure.  These flyweights should "held" by the valve train pressure.

Do a compression test again.......Should be at least 120 PSI with a correct compression gauge.  Hope this explains better the decompression system.

[Ben1098]

You added some more info while I was typing,  You have one of the flyweight sets that do not retract fully.  This is an old problem form 5 years ago.

Look at the 2 pins on the dime sized disk...........Notice the flywheel pin notches are slightly open.....not sitting in the bottom of the "v" groves.  The flyweights are made of 2 parts.....the outer notched plate and the extra welded on weight tabs underneath.  The small disk is holding the welded on weights about half open....inside circle is RUBBING against the dime sized disk on it's outer diameter.  You need to grind out the excess material for the new one you bought.

 

Storm front line coming.  Making it short.......look at the used old flyweights.....check clearance/rub are.....if better trade the flyweights....later.

[Prepper]

26 minutes ago, Ben1098 said:

You added some more info while I was typing,  You have one of the flyweight sets that do not retract fully.  This is an old problem form 5 years ago.

Look at the 2 pins on the dime sized disk...........Notice the flywheel pin notches are slightly open.....not sitting in the bottom of the "v" groves.  The flyweights are made of 2 parts.....the outer notched plate and the extra welded on weight tabs underneath.  The small disk is holding the welded on weights about half open....inside circle is RUBBING against the dime sized disk on it's outer diameter.  You need to grind out the excess material for the new one you bought.

 

Storm front line coming.  Making it short.......look at the used old flyweights.....check clearance/rub are.....if better trade the flyweights....later.

Thanks Ben... i do have the old weights, i will check them against the new ones.  Have this improper fit situation been fixed ?  The reason I ask is because I just bought the new complete cylinder head, cam included, and bought a new cam gear, with weights included.

Thanks...

[Ben1098]

I assume the new latest pics are the new cam and head assy?????  It has a problem!!!!!!!!!!.

Poor mfg process information (instructions and drawings) never really go away.  They always pop back up like the turd they are.  I was flown to Mexico for multiple "mistakes" and to T/S with a "fix and rework"---clean up the build information----and only to find the same problem pop up again 6 months later from the sister supplier, 

This problem was on both Yamaha Rhino and Hisun cam assys a good 5 years ago.  We had Massimo.  Another shop had Yamaha.  They chased a mystery problem to the cam assy.   My new cam assy arrived (with the same runability problem) in the newly uncrated unit..  I did the carbide burr air tool hand mill job on both sets.  EXCESS WELDED WEIGHT GONE.  Other shop has same problem.  His flyweights had all the same machining, stamping marks...with welds identical.....the same sub supplier.  My reworked flyweights were given away to fix the Rhino.

Since you have the old cam, mark the flyweights to MATCH their wear "home" location.  Remove and you should see the rub marks where the little disc hits the rear welded/attached weights.

For the fun part:  you can do it.

1.  Hold the whole cam assy and put the button head pin that sticks thru further to the inside by the exhaust cam lobe DOWN.  Gravity is your friend.

2.  Put your thumb on the button-----should push in below the cam "shaft" profile----as in not the lobes profile----Rotate the disk and the mini cam will push up the button.

3.  Reverse and the button will retract again into the cam shaft area. See how the system works.  Flyweights pulled in by springs...sling out with rotation speed.....disengage the decompression pin.....at engine stop, the springs retract the weights but cannot due to the excess welded weight material profile rub with the small disk.

4.  Pull out the small disk with the 2 flyweight engagement pins.

5.  The "rod" attached (with the dogleg bend) is the minicam within the cam----used to push up the button pin that hits the extra tab on the exhaust side of the big valve cam.

6.  With this pin out, the button can now fall into the hollow main cam center.   Gravity----set down cam button down.  If it falls to the center, no big loss.  Just a pain to reinsert it into hits hole....ship in a bottle syndrome.

7.  You should now see why the your adjustment is wrong.  Rotation of the of the flyweights, rotates the small dime sized disk, which rotates the dogleg rod inside the hollow cam.

8.  YUP, the end of the dog leg is what pushed the pin out further to engage the cam.  BUT. if the small disk cannot fully rotate backwards, the button protrudes out too much and now does a compression release.

9.  Your thinking now, why not just make the disc smaller in diameter........NOPE, not enough meat left for the pin hole wall thickness.

10.  Reassy is just pushing back in the dogleg rod (with the decompression button facing down) and the punch mark up as used in the timing mark.

BTW, use a small 6 inch scale to use as a straight edge to line up the cam bolts, alignment dimple and the cast timing mark in the head.

BEN

[Joe Breaux]

On 3/15/2025 at 11:47 PM, Ben1098 said:

Your pics are of the outer rim of the flywheel.  The tabs in your pics are for the pick up coil......ECU senses the + and - pulses as the square buttons pass under the "face" of the PU coil.  You have a "Missing Pulse" set up here.  Others machines, like 4 wheelers, will only have a Single tab for a single cylinder and a V engine will have 2 with it's marks line up for  IT'S  TDC when they pass under the coil face.  The pick up  coil has a round bar magnet inside and wire wound around the bar magnet.  Take the PU coil and put a small blade screw driver on the face...feel the pull of the PU coil internal magnet.

MAGNETS  Not shown in your  pictures.......they are on the inside of the flywheel.  They will be blocks (sometimes glued to the inside walls.  Some had failures with unbonding but it will destroy the stator knuckles......these are used for charging the battery using the regulator....3 Phase......thus, these are the  3  yellow (white) wires that go to the Regulator.  These have nothing to do with the timing tabs on the outer rim.  Test the magnet(s) inside by taking say a 3/8" extension and roll around the inside.....will pull/stick at the gaps in the magnet bodies.  You can see if the bonding has a crack.

I sure wish you had been around back when I was fighting with mine .I was at the mercy of the only mechanic in my state that would work on these..He was good but slow as paint drying. I learned a lot from him and have managed to keep mine going since. Glad to see you taking the time to help this guy.. We need more members like you.. Thanks from all of us dumbazzes that bought Massimo/ Hisun

[Prepper]

9 hours ago, Ben1098 said:

I assume the new latest pics are the new cam and head assy?????  It has a problem!!!!!!!!!!.

Poor mfg process information (instructions and drawings) never really go away.  They always pop back up like the turd they are.  I was flown to Mexico for multiple "mistakes" and to T/S with a "fix and rework"---clean up the build information----and only to find the same problem pop up again 6 months later from the sister supplier, 

This problem was on both Yamaha Rhino and Hisun cam assys a good 5 years ago.  We had Massimo.  Another shop had Yamaha.  They chased a mystery problem to the cam assy.   My new cam assy arrived (with the same runability problem) in the newly uncrated unit..  I did the carbide burr air tool hand mill job on both sets.  EXCESS WELDED WEIGHT GONE.  Other shop has same problem.  His flyweights had all the same machining, stamping marks...with welds identical.....the same sub supplier.  My reworked flyweights were given away to fix the Rhino.

Since you have the old cam, mark the flyweights to MATCH their wear "home" location.  Remove and you should see the rub marks where the little disc hits the rear welded/attached weights.

For the fun part:  you can do it.

1.  Hold the whole cam assy and put the button head pin that sticks thru further to the inside by the exhaust cam lobe DOWN.  Gravity is your friend.

2.  Put your thumb on the button-----should push in below the cam "shaft" profile----as in not the lobes profile----Rotate the disk and the mini cam will push up the button.

3.  Reverse and the button will retract again into the cam shaft area. See how the system works.  Flyweights pulled in by springs...sling out with rotation speed.....disengage the decompression pin.....at engine stop, the springs retract the weights but cannot due to the excess welded weight material profile rub with the small disk.

4.  Pull out the small disk with the 2 flyweight engagement pins.

5.  The "rod" attached (with the dogleg bend) is the minicam within the cam----used to push up the button pin that hits the extra tab on the exhaust side of the big valve cam.

6.  With this pin out, the button can now fall into the hollow main cam center.   Gravity----set down cam button down.  If it falls to the center, no big loss.  Just a pain to reinsert it into hits hole....ship in a bottle syndrome.

7.  You should now see why the your adjustment is wrong.  Rotation of the of the flyweights, rotates the small dime sized disk, which rotates the dogleg rod inside the hollow cam.

8.  YUP, the end of the dog leg is what pushed the pin out further to engage the cam.  BUT. if the small disk cannot fully rotate backwards, the button protrudes out too much and now does a compression release.

9.  Your thinking now, why not just make the disc smaller in diameter........NOPE, not enough meat left for the pin hole wall thickness.

10.  Reassy is just pushing back in the dogleg rod (with the decompression button facing down) and the punch mark up as used in the timing mark.

BTW, use a small 6 inch scale to use as a straight edge to line up the cam bolts, alignment dimple and the cast timing mark in the head.

BEN

Thanks Ben...

Can you help me understand the decompression function a little better...  what I am struggling to understand is, if the decompression function is causing the exhaust valve to remain open slightly, ( during the "cranking" phase), then why is it I can have 145psi of compression when testing such.  Seems to me that I should have far less compression if the decompression function was malfunctioning.  

I will pull the old weights to check for wear patterns, and attempt to make the same patterns (if any) in the new weights.  Hopefully I can get to that tomorrow.  I'll keep you informed as to my progress. 

[Ben1098]

I assume the new latest pics are the new cam and head assy?????  It has a problem.

Poor mfg process information (instructions and drawings) never really go away.  They always pop back up like the turd they are.  I was flown to Mexico for multiple "mistakes" and to T/S with a "fix and rework"---clean up the build information----and only to find the same problem pop up again 6 months later from the sister supplier, 

This problem was on both Yamaha Rhino and Hisun cam assys a good 5 years ago.  We had Massimo.  Another shop had Yamaha.  They chased a mystery problem to the cam assy.   My new cam assy arrived (with the same runability problem) in the new uncrated unit..  I did the carbide burr air tool hand mill job on both sets.  EXCESS WELDED WEIGHT GONE.  Other shop has same problem.  His flyweights had all the same machining, stamping marks...with welds identical.....the same sub supplier.  My reworked flyweights were given away to fix the Rhino.

Since you have the old cam, mark the flyweights to MATCH their wear "home" location.  Remove and you should see the rub marks where the little disc hits the rear welded/attached weights.

For the fun part:

1.  Hold the whole cam assy and put the button head pin that sticks thru further to the inside by the exhaust cam lobe DOWN.  Gravity is your friend.

2.  Put your thumb on the button-----should push in below the cam "shaft" profile----as in not the lobes profile----Rotate the disk and the mini cam will push up the button.

3.  Reverse and the button will retract again into the cam shaft area.  See how the system works.

4.  Pull out the small disk with the 2 flyweight engagement pins.

5.  The "rod" attached (with the dogleg bend) is the minicam within the cam----used to push up the button pin that hits the extra tab on the exhaust side of the big valve cam.

6.  With this pin out, the button can now fall into the hollow main cam center.   Gravity----set down cam button down.  If it falls to the center, no big loss.  Just a pain to reinsert it into hits hole....ship in a bottle syndrome.

7.  You should now see why the your adjustment is wrong.  Rotation of the of the flyweights, rotates the small dime sized disk, which rotates the dogleg rod inside the hollow cam.

8.  YUP, the end of the dog leg is what pushed the pin out further to engage the cam.  BUT. if the small disk cannot fully rotate backwards, the button protrudes out too much and now does a compression release.

9.  Your thinking now, why not just make the disc smaller in diameter........NOPE, not enough meat left for the pin hole wall thickness.

BEN

 

EXTRA     correct operation    Engine stopped.  The springs pull the sling flyweights back.  The mini cam (all you can see is the disk with the 2 pins) will push the button up and hold the exhaust valve slightly open.....only while the rocker's extra "tab"-----not the cam lobe------ is on the button.......after which time the regular exhaust cam lobe will them rub it's normal slipper pad.  The is the decompression release.  You don't want all fuel/air to escape.....only to unload the stalling hit the starter would take if it was not there.  After the starter gets it spinning good, the "slightly open" time is less and less.....now almost up to full compression.  Hint:  It takes time for the fuel/air being compressed to leak off out the slightly open exhaust valve.  Rotate faster and faster, less can get away every rotation with the same amount of cam button lift.  Hope that makes sense.

Rotation of the cam (faster than crank speed at some point) will sling the the weights out and the small disk will rotate (against the weak springs) via the 2 pins and retract the small pin........the full time run compression position.  The disk has to rotate say some 90 deg between run (retracted pin button) and dead crank start positions.  The extra metal limits the guessed 90 deg to say only 45 deg.

Look at the last or lowest pic.  Notice the 2 pins are NOT in the bottom of the V.  If they were, the timing punch mark in the small disk would almost be covered as the disk rotated CCW some more.  Look at the lower flyweight (easiest to see in the pic but both are excess material) and see the welded metal flyweight tab is rubbing the small disc.  This tab needs to have the same profile of the main body stamped flyweight part.  Not placed correctly in the jig when welded. 

I just scrolled back to your original post about the cam timing.  The old flyweights looked off also but not as bad.  With the pin constantly rubbing the it's rocker "tab", it would eventually grind out the softer tab and make a grove cut and then the compression release didn't work.  Take this assy and do a thumb on the button test and rotate the small disk back and........the button should extend out of the cam and retract full below the shaft profile.

They were stinkers.  Cheap grease in the rear end.  Heads not torqued down....head gasket leak......push out anti-freeze...some toasted or cracked the head.  Purging the air after head work.  Gasket maker drying out (got hard) and not sealing the rear facing drive shaft.  Always feel the hoses for hot ones (means you have coolant flow).  Stupid mini fuel tank...puked on hard steep hill climbs.  Buried series snubber diode (opens=no fan=very BAD) buried in the wiring harness for the radiator fan.  Soft 4WD diff lock up you never shift on the fly.  Replacement cylinders the cam chain rubbed the Al inside the chain chute.  Heat shields not deburred that cut into the O2 sensor heater wire and kills engine only in FWD gears....REV runs just fine.

BTW, I own one.  Bought a swimmer left by drunks at the river so they would not get a DWI----of course they was kind enough to leave the keys in the IGN overnight.  I figured I knew all the bad stuff, so it was my entry level SXS.  Never bought a vehicle that wasn't SICK.  Old farm boy....fixed our own stuff.  Gotta go.

[Prepper]

Hello All...

Still struggling with this 2015 MSU-500 crank, but no start condition.  For those of you who may not have been following, here is a recap.  Purchased cranking but not running.  775 miles and 127 hours on the display.  Previous owner replaced the ECU, Breaker/Fuse box, Fuel pump, Coil and wire, new plug.  I replaced Complete new head assembly (i.e cam, valves, rockers, etc), Fuel Injector, O2 sensor, MAF sensor, Stator/Pickup Coil, air box to throttle body boot.  Engine has good spark, and fuel pulsing out the injector, and well defined timing marks on both the cam and flywheel.  Valves adjusted to .004 intake, and .006 exhaust at TDC (as verified by both the flywheel mark, and piston movement).  Compression tested again today @160psi.  Starting fluid on crank makes no change.

I have attached 1 video of what it sounds like when attempting to start it, and 2 pictures of where the cam timing is at.  The two pictures were taken with the flywheel timing mark in the inspection window.  Keep in mind that the pictures of the cam assembly are at a slight angle as it is hard to take a full frontal shot given the frame/head proximity, but from the drivers-side perspective using a mirror, the cam timing is dead on.  The timing mark on the decompression cam appears to be in the proper position (pointing at the top casting mark on the head).  Also, per Ben's posts (Thank you Ben) the cam decompression weights are free, and snap back to the position you see them in the attached pictures.  The gap between the pin and the v-seat are the same as the old head. 

Today as a test, I adjusted the exhaust valve lash to .012 just to test if the decompression ball was holding open the exhaust valve slightly... this made no change and I have since adjusted it back to .006. 

I think I have run out of ideas.  Any thoughts ???

[Ben1098]

HiSun may have changed the little mini cam rod profile shape so that the now NOT fully CCW disk rotation allows the pin to drop back into the shaft and not affect the decompression function.  5 years ago that was a bad batch of flyweights.  Running Engr Changes are a problem out in the field.  This engine has run before BUT it probably has had many hands in the soup.  With these shop jumpers, sometimes you had to go back 20 steps just to get back to GROUND ZERO.

How did a timing light check out?  HINT:   You can just shine the timing light on the cam and watch the paints at the cam.....BUT you will have a spark at the painted cam timing mark AND an "extra" flash when the cam is 180 out on the other gear mounting bolt.  Anyways, your timing appears to be correct.  You have good compression numbers.  Lets drop back and check the spark plug.  After cranking is the plug wet with fuel?  These machines hate Chumpion plugs.  Go with a new NGK....nothing fancy........ $$$$ tips not req'd.  There were 2 versions of the injectors----the slobbering 2 hole and the spray 3 holer.  Fuel pump pressure should be around 40 PSI.  Exhaust restriction....like did mud dobbers make a summer home in the muffler?  Mouse house in the air box and/or plumbing?  Need good air flow in and out.

Strip it back to just the basic engine.  Pull the fuel pump connector.....removes possible fuel rich condition and ECM control of fuel management.  Good known new dry spark plug.....use compressed air to dry the top of the piston and combustion chamber if flooded or wet down.  Remove the air box to TB plumbing rubber tube.........just the throttle body and without any fuel.  Manually turn the engine over until the exhaust valve is opened fully.  Blow air into the spark plug hole like you are doing a leak down test.  Does the air come out of the muffler with a clean unrestricted rush of air?  Motor is just an air pump---has to have a good flow.  Rotate engine until intake valve is open....same test cannot be done here as the MAP sensor doesn't like that.  Open the throttle body (gas pedal) and direct the  air at the spark plug hole....hear a good flow backwards out the TB? 

Combustion chamber has no residual fuel.       Crank.  Did it try to start?  Shouldn't.     Give the intake TB a short shot of starter fluid.  You should at least get a try to fire and run.....dies after go juice used up......if the engine is solid,  Start adding parts back to the system.  Connect the air box rubber tube to the TB.  TEST.  Add back the air box with the lid removed.  TEST   Crank and supply the go juice as fuel to the air filter body.  Give it longer bursts of go juice to see if engine will run for say 3-5 sec and die.  Connect the fuel pump connector.  KOn (key on)  2 -3 sec pump run to pressurize the fuel rail/tubing.  Pull the fuel pump connector again.  What this does is give the ECM a chance to fire it over BUT if a problem like too rich, it will not be "spoiled" again after the fuel rail pressure drops back....i.e. no more fuel. Should have a short fun and die.  Short burst of go juice at air filter....same start and die?  Looking for same results from before with longer bursts of go juice.  Reconnect the fuel pump connector....KOn......TEST.  Short burst of go juice.  Fire up and continue to run or die?  Need this info to go further.

Try these things first............gets you to the big Y in the road..................you might not like the one path as it gets into Delphi MT05 ECM and it's inputs.

Tell you what.  The Delphi unit has GOOD online information and gives the I/O pinouts on a diagram.  Look further back past the front section Engr Secs and look for the BLACK and GREY CONNECTOR drawings AND the full connection "wiring diagram" page....great if you also own a KAW lawn mower engine---uses the same basic module.

[Prepper]

3 hours ago, Ben1098 said:

HiSun may have changed the little mini cam rod profile shape so that the now NOT fully CCW disk rotation allows the pin to drop back into the shaft and not affect the decompression function.  5 years ago that was a bad batch of flyweights.  Running Engr Changes are a problem out in the field.  This engine has run before BUT it probably has had many hands in the soup.  With these shop jumpers, sometimes you had to go back 20 steps just to get back to GROUND ZERO.

How did a timing light check out?  HINT:   You can just shine the timing light on the cam and watch the paints at the cam.....BUT you will have a spark at the painted cam timing mark AND an "extra" flash when the cam is 180 out on the other gear mounting bolt.  Anyways, your timing appears to be correct.  You have good compression numbers.  Lets drop back and check the spark plug.  After cranking is the plug wet with fuel?  These machines hate Chumpion plugs.  Go with a new NGK....nothing fancy........ $$$$ tips not req'd.  There were 2 versions of the injectors----the slobbering 2 hole and the spray 3 holer.  Fuel pump pressure should be around 40 PSI.  Exhaust restriction....like did mud dobbers make a summer home in the muffler?  Mouse house in the air box and/or plumbing?  Need good air flow in and out.

Strip it back to just the basic engine.  Pull the fuel pump connector.....removes possible fuel rich condition and ECM control of fuel management.  Good known new dry spark plug.....use compressed air to dry the top of the piston and combustion chamber if flooded or wet down.  Remove the air box to TB plumbing rubber tube.........just the throttle body and without any fuel.  Manually turn the engine over until the exhaust valve is opened fully.  Blow air into the spark plug hole like you are doing a leak down test.  Does the air come out of the muffler with a clean unrestricted rush of air?  Motor is just an air pump---has to have a good flow.  Rotate engine until intake valve is open....same test cannot be done here as the MAP sensor doesn't like that.  Open the throttle body (gas pedal) and direct the  air at the spark plug hole....hear a good flow backwards out the TB? 

Combustion chamber has no residual fuel.       Crank.  Did it try to start?  Shouldn't.     Give the intake TB a short shot of starter fluid.  You should at least get a try to fire and run.....dies after go juice used up......if the engine is solid,  Start adding parts back to the system.  Connect the air box rubber tube to the TB.  TEST.  Add back the air box with the lid removed.  TEST   Crank and supply the go juice as fuel to the air filter body.  Give it longer bursts of go juice to see if engine will run for say 3-5 sec and die.  Connect the fuel pump connector.  KOn (key on)  2 -3 sec pump run to pressurize the fuel rail/tubing.  Pull the fuel pump connector again.  What this does is give the ECM a chance to fire it over BUT if a problem like too rich, it will not be "spoiled" again after the fuel rail pressure drops back....i.e. no more fuel. Should have a short fun and die.  Short burst of go juice at air filter....same start and die?  Looking for same results from before with longer bursts of go juice.  Reconnect the fuel pump connector....KOn......TEST.  Short burst of go juice.  Fire up and continue to run or die?  Need this info to go further.

Try these things first............gets you to the big Y in the road..................you might not like the one path as it gets into Delphi MT05 ECM and it's inputs.

Tell you what.  The Delphi unit has GOOD online information and gives the I/O pinouts on a diagram.  Look further back past the front section Engr Secs and look for the BLACK and GREY CONNECTOR drawings AND the full connection "wiring diagram" page....great if you also own a KAW lawn mower engine---uses the same basic module.

Ben, thank you.  Back to basics is an excellent idea.  I will get as much of those suggestions done today as possible.  Question... we're you able to view the latest video of what the engine is doing during an attempted start?  At one point you said you were unable to view on your computer.  Can your computer view YouTube videos?  IF so, I can put that video on YouTube and provide you a link for it.  There are other ways to get you the video also, like Quick Share, Dropbox, etc.  Maybe even snail mail via USB stick.  Let me know.  I think it would be beneficial for you to see the video. 

Thanks again...

[Prepper]

UPDATE:

So... this is interesting.  This is the results of the "timing" test Ben suggested.  I uploaded 1 video, and 2 pictures.  The video is of the cam/timing spinning while cranking (attempting to start.  Plug is in, and the timing light flashes indicate spark.  Seems like too many flashes to me.  Not sure what would cause this, but maybe I should only be concerned with the one flash, at the right time, that makes it run.  I don't know.  The two pictures marked "A" and "B" are stills from the video because its hard to see the cam timing marks in the video while cranking.  Picture "A" is the flash/spark at TDC.  (RED arrow is the CAM timing mark, and the YELLOW arrow is the timing mark on the head).  As you can see... its not flashing/sparking on TDC.  That's a problem I'm not sure how to fix other than moving the cam clockwise about 3-4 teeth.  In picture "B" (same color combo as "A") this is the flash/spark at 180-degrees form the TDC flash.  Again, not where it should be.

However, it appears this would explain why it won't start, yet detonation can be heard out the tailpipe.  Apparently it's firing late.  Does anyone know if there are negative ramifications of changing the cam orientation 3-4 (or maybe more) teeth ?  Will that cause a valve to impact the piston ? 

OR... is it possible (safer) to change the timing of the spark?  How would I do that ?  This is just weird, and I can't think of anything that would cause this other than an misplaced TDC dimple on the cam from the factory.  But the dimple lines up with the cam bolts, so I would think not.

I'm stumped !

[Prepper]

Opps... here is the video.

[Ben1098]

WHOA THERE!!!!!!!!!!!!!!!!!!!!!!!                     Yes, I can do UTube vids.          The pics of timing looks weird.

You need another paint mark on the cam gear.......................the FIRE mark on the flywheel at the notch location transferred to the cam gear..

The flywheel in the first pics looks right with all the pick up coil buttons or tabs.

You need to locate the "F" mark on the flywheel.  Timing on most motors are in the 8-14 deg BTDC area.......the static timing mark at idle.  As the engine RPM increases, the flame front cannot be at the same position away from the piston.....it takes time....very short time....for the flame front to reach the piston dome.  The timing has to start sooner so the ADVANCE CURVE (caused by flyweights in the old points engines) or a Map in ECM units...........will slide from the idle of say 8 deg to something like 28 deg BTDC.

Back to the flywheel.  Hand turn the flywheel to the TDC mark used for cam timing.  Now, slowly rotate the crank BACKWARDS.  About 8 deg back, you should see a line with an F.....the idle fire timing mark.  Mark the cam gear a second time at the head casting arrow.  This will be the point where the timing light will flash at idle.

Rotate backwards even more until you see 2 lines.......this if the full advance point of say 28 deg.  This will slide into view when getting above say 2200 RPM.  Not needed now.

Repeat the timing light at the cam......your new or 2nd paint mark should be at the casting arrow.

[Prepper]

Ben... my flywheel on has 3 lines on it.  There are 2 lines close together, then about 1/2 inch from those 2 lines, is a single line.  My understanding is that the single line is the TDC line, and that's the line that coincides with the timing line on the cylinder.  Not sure what the other two lines are for, but they are real close to the TDC line.

Here are the two videos that I uploaded to YouTube.

General attempt to start video:  https://youtu.be/YEwjWCKSS50?si=riBTrp53Qgs3UsP2

Cam timing video (also can hear the detonations in the background):  https://youtu.be/V7tLV8F6G-Q?si=ZDRqVftru5Q9go-w

Let me know if you can view them.

[Ben1098]

Saw the UTube vids.  Notice the "stall" and hard first crank turn over.............your compression release is NOT working.....starter is good and powering thru to get it spinning.

I could not determine the flashes of the timing light from the video.  Back to the Cu wire and finding the TDC mark.  Degrease and put in a small white dot to mark (and be easier to quickly spot) just like the cam.  Determine that this is still the case......no timing chain jump.

Normally, RICE BURNER (old slang for the Japan Mfg, like LIMEY for British and CHINO is for HiSUN) machines cranks have 4 marks.  TDC-----piston is at the top and rocks up and down as this timing mark is rocked back and forth with the crank. Cam gear dimple (now painted) will be at the cast notch at the top.

F line......static timing line for low RPM (and cranking).......the ignition spark time......around 8 deg BTDC....have to manually turn backwards to this line from TDC.

FULL ADVANCE spark line (dual parallel lines).  The reason for the 2 lines close together......the high RPM advance is say 28 deg BTDC but there is some tolerance so the one mark might be 26 deg and the other 30 deg.

Your cam gear has 46 teeth.  Crank gear has 23 teeth........the 2:1 ratio required for the cam to run at 1/2 the crank RPM.  Knowing this, you can do some quick math and determine each tooth at the cam is close to 7.8 deg each of the cam.....and close to 16 deg of the crank. 

The static (idle=8 deg) timing mark will have the cam gear rotate backwards about only 1/2 tooth at the cast head timing mark.  The double parallel lines (FULL advance at 28 deg crank) would be close to the 2nd tooth back.................was used to check if the spark advanced as RPM increased to say 2200 RPM.

You are describing the TDC single line and after you rotate backward the  0.50" the double lines.........STATIC (8 deg BTDC advance) timing mark.....about 1/2 tooth on the cam.

Leave the spark plug out (pull the fuel pump connector) and repeat the timing light test-----will only have the plug hole whistle.  WHAT LIGHTS UP and WHERE????  SHOULD have the cam's white dot move slightly BTDC....and of course the wasted spark.  Do it in reduced light so the mark pops out on the video so I can see where the ECM is firing the IGNITION.            BEN

[Ben1098]

Dimmed my monitor............I SEE......Your timing is out in the weeds like 90 deg at the cam=180 deg at the crank.  Cam gear is upside down to the cam punch mark.  Same as I saw in your still a couple posts back.

Revisit the cam gear installation.  Before taking the cam gear off, rotate the engine to the TDC (with painted cam gear at the casting mark) as before.  The rockers should be up (valves closed).  Look into the rocker valve adj lid hole at the rockers.  The cam lobes (BOTH) should be down....no lift on the rocker and the valves closed.  For this timing, you have to be in OVERLAP with the Exhaust going off and the Intake coming on at the second TDC of the 720 deg rotation per cycle.  Ain't no 2 stroke.

WARNING:       This is sorta dangerous right now.......you got some spring energy wanting to eat your fingers if you remove the cam gear bolts.  Rotate the crank until the cam lobes are down (COMPRESSION) and the valve springs are unloaded.  Now safe to pull cam bolts.

Check for the punch mark on the end of the cam.......should be pointing to the head casting timing mark.  Match the cam gear, etc.  BEN

[Prepper]

5 hours ago, Ben1098 said:

Saw the UTube vids.  Notice the "stall" and hard first crank turn over.............your compression release is NOT working.....starter is good and powering thru to get it spinning.

I could not determine the flashes of the timing light from the video.  Back to the Cu wire and finding the TDC mark.  Degrease and put in a small white dot to mark (and be easier to quickly spot) just like the cam.  Determine that this is still the case......no timing chain jump.

Normally, RICE BURNER (old slang for the Japan Mfg, like LIMEY for British and CHINO is for HiSUN) machines cranks have 4 marks.  TDC-----piston is at the top and rocks up and down as this timing mark is rocked back and forth with the crank. Cam gear dimple (now painted) will be at the cast notch at the top.

F line......static timing line for low RPM (and cranking).......the ignition spark time......around 8 deg BTDC....have to manually turn backwards to this line from TDC.

FULL ADVANCE spark line (dual parallel lines).  The reason for the 2 lines close together......the high RPM advance is say 28 deg BTDC but there is some tolerance so the one mark might be 26 deg and the other 30 deg.

Your cam gear has 46 teeth.  Crank gear has 23 teeth........the 2:1 ratio required for the cam to run at 1/2 the crank RPM.  Knowing this, you can do some quick math and determine each tooth at the cam is close to 7.8 deg each of the cam.....and close to 16 deg of the crank. 

The static (idle=8 deg) timing mark will have the cam gear rotate backwards about only 1/2 tooth at the cast head timing mark.  The double parallel lines (FULL advance at 28 deg crank) would be close to the 2nd tooth back.................was used to check if the spark advanced as RPM increased to say 2200 RPM.

You are describing the TDC single line and after you rotate backward the  0.50" the double lines.........STATIC (8 deg BTDC advance) timing mark.....about 1/2 tooth on the cam.

Leave the spark plug out (pull the fuel pump connector) and repeat the timing light test-----will only have the plug hole whistle.  WHAT LIGHTS UP and WHERE????  SHOULD have the cam's white dot move slightly BTDC....and of course the wasted spark.  Do it in reduced light so the mark pops out on the video so I can see where the ECM is firing the IGNITION.            BEN

Ben... pro tip on the video... when the video is playing, if you tap anywhere in the video screen options will appear.  Tap on the Gear icon and you will see a list of options.  Tap the playback speed option and select .25.  It was easier for me to focus on the  flash of the 180 degree flash in order to determine where the TDC flash was firing.  It's obvious that it's several teeth off.  However, I am certain I have the [single] line on the flywheel in the window when I set the cam dimple to align with the TDC casting mark on the head.  So either the mark on the cam was placed incorrectly,  or the flywheel mark was stamped I correctly.  However, right as the video starts (you noticed the compression relief was not working) it seems evident that the cam/crank timing is correct because of the (I'll call it the "stall") of the movement indicates maximum compression.  At that point the flash illuminates and the position of the cam aligns with the casting mark on the head.  (I'll follow up more later)

[Ben1098]

20 sec video.  Hit play.  Time bar slider moves.  Any tap on the blank screen throws me into full screen. no audio, no video.  Times out---done.

UTube video.  I see the white mark "flashing" at the 90 deg point (9 o'clock with 12 being the cast index in the head).  Confirm the cam lobes are down (valves closed) when the white mark on cam gear is at the top (12 o'clock) position and piston is at the very top TDC.  If you got that, you are timed mechanically.

If that is correct, you have one of three things going on:

1.  The flywheel buttons or tabs "missing or skip tab" is off relative to the flywheel center keyway....which is locked to the crankshaft.  The TDC was confirmed with the Cu wire test touching the  top of the piston.  Inside, the 18 knuckle poles stator (3 Ph. gives 6 magnet pairs) are independent of tabs on the rim...charging only.

2.  Wrong part # ECM       (DElLPHI MT05).......The pin outs are all the same.  Software maps and advance curves are what change per application..

                                                                       OR  

3.  The MT05 is for a 90 deg V twin motor w/ dual coil outputs.......... example is the KAW and KOHLER engines used on high end Zero-Turn mowers. 

The MT05 has 2 coil output pins:         COIL A is pin J1-10    w/   J1 is Grey                   and           COIL B is Pin J2-01     w/   J2 is Black      Prior techs swap the pins????

eBAY Store of MOTORCYCLE DOCTOR.  He carries HiSun parts and P/N.  You have 2 parts to check out.  Seen he has helped others on this forum.  BEN

 

[Prepper]

4 hours ago, Ben1098 said:

20 sec video.  Hit play.  Time bar slider moves.  Any tap on the blank screen throws me into full screen. no audio, no video.  Times out---done.

UTube video.  I see the white mark "flashing" at the 90 deg point (9 o'clock with 12 being the cast index in the head).  Confirm the cam lobes are down (valves closed) when the white mark on cam gear is at the top (12 o'clock) position and piston is at the very top TDC.  If you got that, you are timed mechanically.

If that is correct, you have one of three things going on:

1.  The flywheel buttons or tabs "missing or skip tab" is off relative to the flywheel center keyway....which is locked to the crankshaft.  The TDC was confirmed with the Cu wire test touching the  top of the piston.  Inside, the 18 knuckle poles stator (3 Ph. gives 6 magnet pairs) are independent of tabs on the rim...charging only.

2.  Wrong part # ECM       (DElLPHI MT05).......The pin outs are all the same.  Software maps and advance curves are what change per application..

                                                                       OR  

3.  The MT05 is for a 90 deg V twin motor w/ dual coil outputs.......... example is the KAW and KOHLER engines used on high end Zero-Turn mowers. 

The MT05 has 2 coil output pins:         COIL A is pin J1-10    w/   J1 is Grey                   and           COIL B is Pin J2-01     w/   J2 is Black      Prior techs swap the pins????

eBAY Store of MOTORCYCLE DOCTOR.  He carries HiSun parts and P/N.  You have 2 parts to check out.  Seen he has helped others on this forum.  BEN

 

Ben... I have attached a picture of the ECM.  It's a MT05, but I am confused if my MT05 is the correct one for my single piston engine, or the ECU for a single piston engine is a completely different part number. 

If the MT05 is NOT the correct part number for my engine... then this whole situation of crank but no start makes sense.  From what I understand about the history of the machine, it quit, and in spite of throwing parts at it (including a new ECM), it never started again.  As I understand it, it appeared the fuel pump stopped working so they replaced it with a new one.  When that didn't cure the problem they eventually arrived at taking a look inside the fuse/relay box to see if any fuses or relays were broken.  They damaged the box trying to get it open, and called it quits, and sold it to the guy I bought it off of.  He ordered the relay/fuse box but sold it to me before the part arrived.  He gave me the part after it arrived but of course that didn't cure the no start issue.  When I got it the issue seemed to suggest a timing issue so I checked the valve lash clearances.  It was then that I saw the lobe for the exhaust lobe was about half worn off.  I figured that by the time I paid for a new cam, rockers, and valves, etc. I could just buy a complete head assembly for a few bucks more.  I didn't think the cam was wore off enough to keep the engine from starting, but it was worn enough that it needed to be replaced, and now would be a good time rather than later.

Regarding the question about prior techs swapping pins, I think there is less than a 1% chance of that having happened.  I will call Motorcycle Doctor tomorrow morning and see what ECM I should have.  I bought the head from them, and also a seat assembly so they have had some business from me recently.

Thanks...