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Discussion Starter · #1 ·
So I had the machine out messing around in the driveway today kinda doing a few donuts, started going straight agin and machine dies. Start it back up put it in reverse starts going dies again. Start it as soon as I put it in gear dies like something is stuck. Back in forward then it goes now ride it around and seems fine.

I did a clutch but that was 70 miles ago so I assume if it wasn't out together right it would have done something before now?
 

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Discussion Starter · #3 ·
It's like the belt was stuck in the clutching. Would run fine in neutral. As soon as you put it in gear it lurched and died
 

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That sounds like the wet clutch was locked up when you put it in gear. It will lurch if you have any revs on the motor when switching it into gear but never had mine die. Dunno, just keep riding and see if it happens again. If the nut on the sheave backed off, I think it wouldn't run fine after so probably not that.
 

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Discussion Starter · #5 ·
Thought about that, but not sure how that's possible unless you broke a spring in it. But then I would think it stay stuck open.

Only thing I can figure is that because I was on ice and went from a higher rpm to like a dead stop that clutch closed faster than the belt cold move? But that don't make a lot of sense to me.

Whole think seems weird to me. Likely going to pull the clutch cover and take a look for piece of mind
 

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Hmmm, that actually makes a lot of sense. If you were wide open and the sheave was in high gear then a sudden lockup. When you start again, it would be like you were trying to take off in 5th gear. That would kill it until you put in neutral to let the belt shift back down.
 

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So I had the machine out messing around in the driveway today kinda doing a few donuts, started going straight agin and machine dies. Start it back up put it in reverse starts going dies again. Start it as soon as I put it in gear dies like something is stuck. Back in forward then it goes now ride it around and seems fine.

I did a clutch but that was 70 miles ago so I assume if it wasn't out together right it would have done something before now?
There is a one-way sprag clutch involved in the wet clutch that tends to cause this symptom if it is jammed or installed backwards. The belt on the Yamaha system is always fully engaged. Some snowmobile type CVTs actually release the belt to act as a clutch to allow the engine to idle while not moving.

The real "clutch" in the Yamaha system is the "wet clutch" which allows the engine to idle while in gear. The one-way sprag clutch is there to keep the drive train in engagement if the drive train is spinning faster than the engine crankshaft. This gives you engine braking while you are decelerating or going downhill. When the engine (at idle) RPM is higher than the drivetrain RPM the one-way disengages and the vehicle can stop without the engine dying.

The wet clutch (and one-way clutch) are behind the primary sheave, under a bolted on bearing plate that supports the shaft that the primary sheave rides on.
 

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Discussion Starter · #11 ·
It sounds like the cvt didn't back shift all the way or the one way bearing was sticking.
So you think it will be ok or I need to dig into it more. Wet clutch is slugged but didn't do anything else to the wet clutch. Hunterworks sheave kit in it
 

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Discussion Starter · #13 ·
I should also add that with my sheave I'm only hitting about 55 MPH. Which I don't really care about the top end I just wanted it for the bottom end. Just seems kinda low compared to others. Between the sheave and power Commander it seems to have pretty substantial low end gains
 

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It is somewhat common that a sprag falls out when the clutch is taken off of the machine. If it is put back in backward, the single sprag will be grabbing in the wrong direction even if the assembly is put in in the correct orientation. It may be that the sprag then gets damaged, or scores up the races that it runs on, which leads to a jamming of the whole affair. There are tiny grooves on each sprag that need to be oriented in the proper direction. The photo below shows a close-up of those grooves and the proper orientation of the "outside" stamping and green dot with respect to the clutch carrier behind it. Inspect the raceway surfaces on the clutch carrier and the center of the drum as well as the surfaces of all of the sprags for scoring.



Probably more common, is a mistaken orientation of the "outside" marking if the one-way is installed into the drum with the words showing. Shown in red in the picture below. The one-way should be installed onto the clutch carrier first, with the "outside" marking showing. Then the "outside" is indeed facing away from the engine proper. This is not so likely in your case because the malfunction was delayed from when you started using the machine after installing the wet clutch. This is shown in green below.

 

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Discussion Starter · #15 ·
Thanks. I didn't pull the one way bearing so it couldn't be that. It's possible that a spring is twisted or broke. But I seems kinda odd that it did it about 70 or 80 miles after I installed the slugs? I didn't pull any springs when I installed the slugs just put the slugs in and put it back together. I've driven it about 30 miles since then and no problems, if a spring was broke wouldn't it always hang up?
 

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Thanks. I didn't pull the one way bearing so it couldn't be that. It's possible that a spring is twisted or broke. But I seems kinda odd that it did it about 70 or 80 miles after I installed the slugs? I didn't pull any springs when I installed the slugs just put the slugs in and put it back together. I've driven it about 30 miles since then and no problems, if a spring was broke wouldn't it always hang up?
Thought about that, but not sure how that's possible unless you broke a spring in it. But then I would think it stay stuck open.
Only thing I can figure is that because I was on ice and went from a higher rpm to like a dead stop that clutch closed faster than the belt cold move? But that don't make a lot of sense to me.
Whole think seems weird to me. Likely going to pull the clutch cover and take a look for piece of mind
I think it was a reference to the clutch shoe retraction springs? It is a centrifugal clutch where the clutch shoes want to fly out from the center as the crankshaft rotates. Each shoe has a spring that holds it back such that it does not actually contact the drum until a certain RPM is reached. With a broken or missing spring, that particular shoe would be dragging on the drum, even at idle speed. Just for information, the clutch weighting slug kits add weight to each shoe such that it flies out and engages at a slightly lower RPM.
 

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Discussion Starter · #17 ·
Yeah I guess it's completely possible that a retraction spring is broken. Now I guess I should probably pull the wet clutch when I get a chance and check all the springs in it.
 

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Yeah I guess it's completely possible that a retraction spring is broken. Now I guess I should probably pull the wet clutch when I get a chance and check all the springs in it.
That would be a good time to carefully inspect the one-way clutch sprags and raceways. There is a photo of a one-way that appears to have flat spots on the sprags. From another site, but possibly a similar problem.

 

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Discussion Starter · #19 ·
I think it was a reference to the clutch shoe retraction springs? It is a centrifugal clutch where the clutch shoes want to fly out from the center as the crankshaft rotates. Each shoe has a spring that holds it back such that it does not actually contact the drum until a certain RPM is reached. With a broken or missing spring, that particular shoe would be dragging on the drum, even at idle speed. Just for information, the clutch weighting slug kits add weight to each shoe such that it flies out and engages at a slightly lower RPM.
Now that I think about it this could be possible. I have noticed that it sometimes seems to want to kinda stick sometimes when shifting.
 

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Yes, mine was kinda sticking in gear when I got it. Once I got her out the machine locked in reverse on a decline but not in gear. I drug it out backwards about 30 yards until it finally popped out of reverse. Drove back to trail head and sounded like rocks in drivetrain. Have 30 miles on it and it's at the dealer. No word on the damage yet. Still waiting the results of tear down. Monday will be 2 weeks.
 
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