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Losing RPM and not holding normal top speed

YamahaTim

YamahaTim

Lifetime Member
Joined
Sep 21, 2013
Messages
2,089
Age
53
Location
Farmington, MN
Country
USA
Snowmobile
2014 Yamaha Viper LTX SE MPI Turbo
I was losing rpm. it would go from 8800-8900 to 8300 max. One ride i would be running normal rpm, then maybe letting it sit for a few hours or over night, then my sled would only run 8300 rpm and slow top speed. and while it was running low rpm i would feel a grabbing or binding or slipping. it was on and off. sometimes normal, sometimes low rpm and low top speed. well i put a forth wheel kit in and wheels where my limiter strap go and a extra set on my skid in the middle. didnt help. so i brought it to the dealer. there is something going on as i went through 4 belts. i would only break a belt if it was running low rpm and it was binding and while doing that the clutches were really hot!

brought it to the dealer each time i broke a belt. they would change a spring or change helix, but never really fixing the problem. after the fourth belt and some damage to the side panel and the lower belly pan, they took a serious look at it. they took apart both my primary and secondary, looked at the bearings, looked at the jack shaft, looked at the motor mounts, and looked at the alignment. everything looked to be fine. so they tested the clutches and found them to be really hot. So they just for shi*s and giggles they put some shims in the secondary and put the 8DN belt on which is the Nytro belt. and a different angle helix in. now i have all stock Yamaha parts in my clutches with different weights. so after trying the 8DN it worked perfect. way way cooler, no slipping or binding. ran it for awhile and it kept the same rpm. so i went to pick it up. brought it home last Friday night and went for a 100+ mile ride and it ran perfect. 8800-8900 rpm and held that no problem no matter the condition. We got up early Saturday and went on a 200+ mile ride and same thing ran perfect kept 8800-8900 rpm and held that at wot all the time. no slipping or binding. And right after some hard miles i would take off the side panel and it was easy to put my hand on the clutches. warm but not real hot. belt looks in really good condition. I dont know what the problem was, or if it was something that Yamaha needs to take a look at, but its fixed right now. whether its fixed right or just a different fix, but it works. And I talked with a lot of different people and know one could figure it out. But now its fixed and im running 8DN belts which i have a few of. Im not sure if its going to be a long term fix? But it seems to work really good and it pulls just as hard if not harder now. I will be talking with my dealer to get the facts, as i was in a hurry to get my sled home and test it. once I get the facts I will report back.
 

Pictures and part numbers would be great!!!!
 
Cant really see the number on the belt. will turn it so you can see. in a while.
 

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Ok , so on the back side of the secondary clutch those three screws they put shims in to get the belt to ride higher in clutch , and what angle helix did they put in and spring ?
 
By enlarging Tim's picture it looks like a straight 47 degree Yamaha helix (8BV71), but can't tell which spring.
 
I know you have a turbo but what weights are you running?
I'm going to put heavy hitters in and try this shims in the clutch to get the xs805 belt to work
 
09nytro said:
I know you have a turbo but what weights are you running?
I'm going to put heavy hitters in and try this shims in the clutch to get the xs805 belt to work
Click to expand...

I'm running Hauck Powersports weights. Otherwise everything is stock. Blue silver blue primary which Yamaha. White white primary spring and I think if I have my numbers right I'm running 13.4 grams. On each weight. But I don't know the weight of the actual weight. So far it's been perfect.
 
Something fishy there with that longer belt etc... I'd be checking the center to center on your clutches no way should you need a longer belt.
 
TurboJamie said:
Something fishy there with that longer belt etc... I'd be checking the center to center on your clutches no way should you need a longer belt.
Click to expand...

It's not that I need a longer belt. It's just that when they tested mine with the stock belt the clutches were super hot. And they have 450hp sleds that run on the 8DN so they tried that and it worked. 11 mm longer but it's also wider. So adding shims helped the belt fit in there and so far so good.i have almost 400 miles on with that belt and no signs of damage and it runs perfect. 8800-8900 rpm and I don't feel the slipping that I did before. :Rockon:
 
Im wondering how many people are having this problem. I would rather run the Nytro belt anyway, its proven!! :-o
 
Is there more to this story? Only the belt change doesn't seem like it would cure a clutch binding situation. Did they modify the secondary in any way? If the belt is wider how does if fit in the primary clutch? I am not saying I don't believe YOU but am wondering if they did something else also.......
 
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