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Losing RPM and not holding normal top speed


Someone else wrote something about the 8DN belt. But that what's this is about. So I hope it's working as good for others as it did for me. It not only pulls harder, but it looks a lot better. I see no signs of wear. The clutches are a lot cooler. Wonder what's going on??? Pretty close to 3000 moles on sled, but around 500 on 8DN and looks perfect! It has lasted 100 miles more than any stock Viper belt so far.
 
Maybe maybe not. He did say they tightened up the secondary. Like I said the 8dn is not as far off as thought. I suspect the Viper belt being narrow rides lower in both primary and secondary. Need to take a measurement of belt in primary.
 
Now that it's back at the shop they are going to take a look at the clutches again to look more into it. And fix my new problem, but that's a different thread.
 
Here's some food:
I just did a #*$&@ load of work on a turbo cat , lot of parts from OSP and a new belt , so after all that work belt stayed on for 700 miles and the clutches are nice and cool , with that said I pulled the belt off ( which is a dayco ) the dayco belt is alittle over a 1/4" longer than the cat belt is , so maybe OSP is on to something too !

Maybe cat came up with this belt ....hummmmmm........
 
09nytro said:
Here's some food:
I just did a poop load of work on a turbo cat , lot of parts from OSP and a new belt , so after all that work belt stayed on for 700 miles and the clutches are nice and cool , with that said I pulled the belt off ( which is a dayco ) the dayco belt is alittle over a 1/4" longer than the cat belt is , so maybe OSP is on to something too !

Maybe cat came up with this belt ....hummmmmm........
Click to expand...

Its kind of funny that the 8DN belt works better and stays cooler??? Im pretty sure it fixed my problems!
 
I was testing the belt the whole weekend until my oil spill and the belt worked perfect, no slipping no binding and it pulls all the way up. Now I'm a little heavy on the weights cause I'm down a few hundred rpm. Bit it pulls great and looks perfect like new. Except dirty...
I will do some weight tuning on the clutch to see if I can't get her to run 8800+ rpm.
 
YamahaTim said:
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.
Click to expand...
 
I run a 8dn on my 15 turbo viper. It is a little longer and a little wider. I tried it after installing trail clutch kit from ullmer and no other adjustments. Definitely changed top end. Occasionally would "slip" out of gear when driving slowly or "stick" a little after stopping. Ullmer sells a machining service to run an 8dn which I have no doubt works. But I have been very happy with a few setting changes to make it work. P.S. 2000 miles without blowing a belt and running lots of hp and hard launches. I am on 2nd belt but the old belt is still my spare. The 8jp makes a lot of dust and slips where the 8dn is softer and bites harder. I prefer the 8dn at half the price. Even with a few clutch modifications it' cheaper to convert if you keep the sled for more than a couple years.
 
Yamatuner said:
I run a 8dn on my 15 turbo viper. It is a little longer and a little wider. I tried it after installing trail clutch kit from ullmer and no other adjustments. Definitely changed top end. Occasionally would "slip" out of gear when driving slowly or "stick" a little after stopping. Ullmer sells a machining service to run an 8dn which I have no doubt works. But I have been very happy with a few setting changes to make it work. P.S. 2000 miles without blowing a belt and running lots of hp and hard launches. I am on 2nd belt but the old belt is still my spare. The 8jp makes a lot of dust and slips where the 8dn is softer and bites harder. I prefer the 8dn at half the price. Even with a few clutch modifications it' cheaper to convert if you keep the sled for more than a couple years.
Click to expand...
Yamatuner look at the date on post above yours. Is still relevant but just saying.
 
Yeah I seen it. But just thought I'd let you know how my setup worked out. Lol
 
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