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By Chile
2018 Massimo 700 MSU. The machine started burning oil all of a sudden. One day fine-- next morning burning oil. Looking for advice. Do I pull the engine to inspect the top end or can it be done with the engine in place? Pro? Cons?
Any and all assistance is greatly appreciated in advance.
Chile
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By Chile
2018 Massimo MSU 700 EFI. I realize that this engine is essential the same as in all of the HISUN based Yamaha clones out there. I am in the process of performing a top end diagnosis/rebuild. I have an AMAZON top end rebuild kit on order in anticipation of this activity.
Question 1: When exploring the myriad of top end rebuild kits on the market for these units there are some cylinder assemblies that have "686 cm3" badging next to the cam cain tensioner boss. Others compatible with the unit do not have this badging. The existing cylinder assy does not have the 686 badging. I am assuming that this simply verifies that the cylinder assy is for a 686 cm3 engine which of course the stock 700 series HISUN engines are. Am I missing something here or is this just a manufacturer artifact? With or without the badging the application listings all indicate compatibility with the MSU 700 series engines.
Question 2: I have reviewed at minimum a dozen videos associated with this rebuild. To date I have not found one that deals with piston/cylinder clearance and/or ring gap verification. The advertised specifications for these various "top end rebuild kits" all indicate: Cylnider bore = 102mm and piston diameter=101.5mm. The math yields a .5mm (as in 1/2 mm) difference. That seems to be a very large piston/cylinder clearance. I realize I am referencing advertised specs rather than emperically measured values but the numbers have gotten my attention. I have referenced the FSM and found it to be somewhat confusing in this regard. Hopefully the experts on this forum can enlighten me as to where my observations are faulty here.
Any and all assistance is greatly appreciated .
Thank you all in advance,
Chile
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By Prepper
I have been doing a little research on which engine oil is best for UTV engines. There seems to be some disagreement over using a good quality regular engine oil, and the necessity of using "M2" (or wet clutch suitable) oil. My understanding is the "wet clutch" suitable oil has less friction reduction properties (hence a more responsive clutch with less slippage). While less friction reduction properties would seem to be better for the wet clutch... it would not be best for the internal engine parts like camshaft bearings and other moving parts where friction is detrimental and would lead to premature failure. Some folks swear you need M2 oil, while others say they have been using regular motor oil for years and their clutch is just fine. Could they both be right ???
Any thoughts ?
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By Hunterman22
2021 Hisun Axis 500 UTV (From Lowes)
Will NOT START
MY apologies if this is to much info just wanted to give yal the most information possible for help.
I'm a so called diyer. An Electrician by trade 21yrs. I got my S×S from my last job. The contractor purchased this S×S for this specific job brand new, from Lowes. They used it for hauling materials, tools, & a little bit of anything you can think of on an Industrial type job site.
I remember getting on the SxS one time & pushed the gas petal all the way to the floor & SxS had very little power.
So anyway ,when the job finished up back mid July this year (7/2024) , I asked the contractor what they was going to do with it. I was told to take it. Otherwise it would go to the contractors yard (storage yard) & most likely rust away.
Took it home washed it , it had a heavy coat of dust on it & in it dust was every where. My helper & I had to push it on the trailer to get it home. After washing it throughly I let it sit & dry out for a good day and half, maybe 2 days. Before trying to start it. NO START. Will turn over & try to start but thats it.
So here's what I've purchased & installed. New Air Filter, new spark plug, new air idle control valve (AICV), new throttle position sensor, new throttle body, new oxygen sensor, new digital dash speedometer/fuel gauge/clock.
Also drained the old oil & gas & replaced with new oil & 93oct. gas. I should probably mention that I've changed the AICV twice. The 1st time I changed the AICV I was able to get the SxS started & let idle for at least 10-15min. Drove out of the garage, with very little power, turned it around & barely got it back in the garage.That was the one & only time I've been able to start the SxS. I've also cleaned the Throttle Body and & intake with TB cleaner. So after that the AICV was making weird noise so I pulled it out & tried cleaning it, pretty sure I messed it up. So I purchased a Throttle Body that came with new AICV & TPS. Still NO START. I've checked the fuel pump & the fuel injector. I took the injector off still hooked up to wiring & turned the key over, the injector sprayed a lot of gas out kinda the size of a volleyball. I've also checked the clearance gap on the intake & exhaust valve. But today 11/2/2024 I'm going recheck spark plug gap & the valve gaps. And alot of other checking. Would the driver side seat belt have anything to do with it not starting?? I know the driver side seat belt has to be in gauged for full throttle "going fast". Thing is the drv. side seat belt will latch but feels like might be messed up inside of it. Tired opening it up but to no avail. I've never had a S×S or 4wheeler so I was really excited when I got the S×S,not so much anymore. I work on & fix my own vehicles usually no problems. But this SxS is kicking my ass.
So if possible & someone could help me with some ideas or tell me what Im doing wrong or did wrong, I would greatly appreciate it. Thank you for reading thus far.
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By 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.
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