2016 Massimo MSU500 Setting Top Dead Center

[res2fr]

I have an issue and I'm hoping that someone can help with a little Wisdom. I have a 2016 Massimo MSU500 UTV that blew a time chain while out riding. It has been torn down to replave the chain and Sprocket amount other things that will be renewed. The problem comes in with setting Top Dead Center on the motor. The Manuals all teel one to line up hash marks on the flywheel with a point on the side cover under what's referred to in several place as a manhole cover. Its a large headed cap/bolt that unscrews and allows you to view the edge of the flywheel. There are hash marks on the flywheel that your supposed to turn the crank until you get the proper alignment between a certain hash mark and a reference point on the Case. Problem is there is NO reference point on the case there. I also have another 2016 MSU500 and a 2014 Coleman 500. Not one of these machines have a reference mark of any kind in that location. (I have pictures if needed) 

  I know I can use the old pull the valve covers and rotate the crank and rely on getting the right point where Both Intake and Exhaust valves are closed at hopefully the correct point in the piston stroke. Is there any other reference point that could be used for this or is this the only thing left to use for finding TDC? Gotta Love documentation that doesn't match the equipment it's supposed to be for, any help would be greatly appreciated. Even if just to tell me that's about my only option. 

 

Thanks to all who even take the time to read my rambling question.

Robert

[Ben1098]

Remove the spark plug.  Rotate the engine until the piston is at the top of travel by using a copper wire (soft 10 AWG with rounded end down) and watch the travel up and down.  When very close to TDC, the piston will stop going up and "stall" for a bit and then start to fall back down.  Rotate "between these two positions" and you have TDC.  Easier said than done.  A dial indicator can also be used if you have the set up.  Getting into the fan side is a pain with the cover.....bolt screw nut inserts usually "spin".  Easiest is to take off the belt cover exposing the drive clutch pulley.  On the rim of the pulley you can make an narrow ink mark (or tape with a ink pen line).  Do the rock back and forth to find the "going up"   and    the "going down" location on the case.  Mark the two locations.  In the middle is TDC.  Also, try to see if you can find the timing marks noted in the service manual and mark both with paint for future use.

I had a simple trick (POSTED) to hold the chain in place and keep it from falling off the crank sprocket when installing the cam gear.....string pulled for a 3rd hand.  I like to do a double check after timing the cam and then rotate to the OVERLAP (EXHAUST VALVE closing and INTAKE VALVE just opening) at the other TDC than Compression.  Always rotate slowly by hand to check for valve interference.  If something is wrong, you don't bend any valves.  Rotate the decompression flyweights against the spring return to avoid being fooled by the cam's AUTO decompression mini-cam/button hitting the cam follower.

[motojoe]

Look at the "Man Hole" threads and you will find a cut into the threads, line this up to the flywheel timing marks and that will be your TDC.

[Steve G.]

I'm betting the marks are there just very easy to miss as they fly by that hole when looking and turning the shaft. My motor actually has some leading marks a V mark, the mark is TDC.

 

[res2fr]

On 12/13/2023 at 6:09 PM, motojoe said:

Look at the "Man Hole" threads and you will find a cut into the threads, line this up to the flywheel timing marks and that will be your TDC.

Thank you for the reply and option to check. Unfortunately, I have 2 2016 MSU500s and 1 2014 Coleman 500 and None of them have such a marking but it was worth checking. I dug out my Endoscope hooked it up to my Cell phone and did a direct visual, 360 degrees and no mark. But then the manuals show reference points that don't exist. I'll probably try the Old physically locate TDC and go from there the best I can.

 A.

Robertgain, thank you for your time and input 

[res2fr]

On 12/9/2023 at 3:58 PM, Ben1098 said:

Remove the spark plug.  Rotate the engine until the piston is at the top of travel by using a copper wire (soft 10 AWG with rounded end down) and watch the travel up and down.  When very close to TDC, the piston will stop going up and "stall" for a bit and then start to fall back down.  Rotate "between these two positions" and you have TDC.  Easier said than done.  A dial indicator can also be used if you have the set up.  Getting into the fan side is a pain with the cover.....bolt screw nut inserts usually "spin".  Easiest is to take off the belt cover exposing the drive clutch pulley.  On the rim of the pulley you can make an narrow ink mark (or tape with a ink pen line).  Do the rock back and forth to find the "going up"   and    the "going down" location on the case.  Mark the two locations.  In the middle is TDC.  Also, try to see if you can find the timing marks noted in the service manual and mark both with paint for future use.

I had a simple trick (POSTED) to hold the chain in place and keep it from falling off the crank sprocket when installing the cam gear.....string pulled for a 3rd hand.  I like to do a double check after timing the cam and then rotate to the OVERLAP (EXHAUST VALVE closing and INTAKE VALVE just opening) at the other TDC than Compression.  Always rotate slowly by hand to check for valve interference.  If something is wrong, you don't bend any valves.  Rotate the decompression flyweights against the spring return to avoid being fooled by the cam's AUTO decompression mini-cam/button hitting the cam follower.

Thank you for your input on physically establishing TDC as I had started working on that already. But I like your suggestion to use the Rim of the Drive Clutch by marking IT once you find the 3 points that you need. I've noticed references to the Firing Range in the manual when dealing with the Flywheel Markingbut have found no further info on what that is. I'll try creating my own TDC marks and Range of sorts.

Ill also look for your post on your trick to keep the Chain in place if it's still available.

 

Again, I thank you for sharing your ideas.

Robert

[res2fr]

12 hours ago, Steve G. said:

I'm betting the marks are there just very easy to miss as they fly by that hole when looking and turning the shaft. My motor actually has some leading marks a V mark, the mark is TDC.

 

I have no real problem finding the marks on the Flywheel on any machine. The one I'm working on now has a new flywheel on it, made for High output Stator. It is a little tougher because that outer edge is very thin and so the mark is Small. but thank you for your input. They do fly by that Timing Hole quickly. I fine my more easily now that I'm using my Endoscope camera on my Cell phone. I just mount the camera, aiming at the hole and watch the Video on my phone. The hardest part here is getting that little camera mounted in place and stationery, have to get inventive at times.

Again thank you for your time and input.

Robert

[Ben1098]

In case you cannot find the chain trick:

Tie a nylon string (I like braided) to the top of the chain loop.  Position the bottom of the chain on the crank gear and they pull up on the string.....tie off onto the SxS roll cage or a storage shelf above if working on a bench assy.  The string tension keeps the the chain on the lower crank gear.  Next, you slide the cam gear onto the cam (no bolts yet as it can rotate BUT get it close to the timing mark.  "Stretch" the string and use a pick to milk on the chain onto the cam gear.  Use an extension to push and mimic the tensioner and check timing marks.  If off a tooth, milk it to the correct position.  The extra 3rd hand.......Rotate the engine  slightly and check for the cam gear to follow......still on the lower gear.

[res2fr]

Thank you for sharing. Sounds like a simple but smart way to simplify a possible problem. I'll probably be putting a chain a couple machines.

Again thank you for sharing.

Robert