Trying The 8DN BELT

[wot-75]

I want to ask a question !

What do you guys think will come in Allen's update / upgrade kit to run the 8 DN ?

What do you think needs to be done to make it work to its full potential ?

From his FB page:

"We are getting ALOT of calls and emails asking about running the old 8DN belt on the new SR Viper models.

Can it be done? Yes

Will your Ulmer Racing for the SR Viper clutch kit work with the 8DN belt? Yes, but the 8DN belt will likely drop your shift RPM slightly.

Our current SR Viper clutch kit does wonders to the SR Viper when using the stock 8JP belt, it makes the sled more consistent on RPM and better belt life, as well as gaining 3-4 sled lengths acceleration.

We are working on a calibration to use the 8DN belt on the SR Viper. It will use the same primary spring, weights, and helix, but it will likely use a new secondary spring and require you to send us both your primary and secondary clutches for some extra machining to make the 8DN belt work to it's full potential. We are currently still in testing on this combination and will have a complete kit (Clutch Kit, 8DN belt, and clutch machining) available. We will have a "upgrade kit" available for those who already purchased our SR Viper clutch kit as well."

 

[YamahaTim]

Nice???

 

[NOS-PRO]

Has anyone changed the center to center to be correct?
Just making the secondary narrower to take up the extra length is not going to fix everything. If the belt is longer, and you make it ride up on the secondary further, this means, it will bottom out the primary first, making the sled slower overall. The other thing running a belt long for the center to center is you are gearing the sled down, so I have no doubt that the sled pulls better, even if the rpms are off. We are talking about 4-6mm different center to center depending on belt variation between the two belts. That is alot when dealing with clutching.
I wish I had one of these sled here and time to fix it. The belt may work better but not without a correct center to center or overdrive in the primary to get back what the lower gear ratio and the clutch bottoming out took away from your gain in a better quality belt. Not to mention, when you lower the gear ratio(make the secondary larger diameter) your changing the effect of the helix and spring on that belt. This changes how the primary will react to these new loads.

To really put this theory to the test, assemble your clutches with no springs, use a warm belt(bends easier) around your clutches, you can tell somewhat close, how your belt will be when the clutches shift out. I say close because under load, the primary will get closer.

can someone measure center to center and see if they can loosen the motor up and how close they can come to the correct distance of 268.5?

Sorry if I seem ranty, I just think many are missing an important piece of this pie. If I am wrong, great, that just means I have learned something.

Someone donate me a viper

you are not wrong, this is the problem exactly......
shimming the belt will do nothing after engagement. I guess some guys enjoy going slower in the end.
A properly shimmed, clutched 8jp works

Suburban - I'm hitting 100 consistanly on trails with powder and a top speed of 105.1 to date on GPS with the 8DN. Yes, the belt is longer than the stock belt...but you know what? These Vipers are capable of 100 plus and I have proved it along with many others that I have helped. How can you say "I guess some guys enjoy going slower in the end."

I have numerous hours into clutching this thing using timers, radar gun, GPS and Speedcheck box and I am not done yet. My intent is to help all Viper owners here get the maximum out of their sled...I have nothing to hide and I share everything I do, if it works or not. Sometimes I get lucky and find a better combination that works, but it's all trial and error.

Ordered more parts yesterday to try a better clutching setup this winter yet.

 

[NOS-PRO]

BetheViper - The center to center cannot be adjusted.

 

[suburban]

I said "some guys".....maybe your not one of them. Work away on which ever belt you prefer. My stock viper has been 110.9 on the junk 8jp.
Your not the only one to clutch and test. I just think in the end if guys put as much effort into making the 8jp work as they have into the 8dn, the belt isn't as bad as everyone is trying to make it out to be.

 

[NOS-PRO]

I said "some guys".....maybe your not one of them. Work away on which ever belt you prefer. My stock viper has been 110.9 on the junk 8jp.
Your not the only one to clutch and test. I just think in the end if guys put as much effort into making the 8jp work as they have into the 8dn, the belt isn't as bad as everyone is trying to make it out to be.

You mind sharing your clutching setup?

 

[stingray719]

I said "some guys".....maybe your not one of them. Work away on which ever belt you prefer. My stock viper has been 110.9 on the junk 8jp.
Your not the only one to clutch and test. I just think in the end if guys put as much effort into making the 8jp work as they have into the 8dn, the belt isn't as bad as everyone is trying to make it out to be.

Proof please as I do not believe this unless mitigating factors like running downhill

 

[suburban]

I said "some guys".....maybe your not one of them. Work away on which ever belt you prefer. My stock viper has been 110.9 on the junk 8jp.
Your not the only one to clutch and test. I just think in the end if guys put as much effort into making the 8jp work as they have into the 8dn, the belt isn't as bad as everyone is trying to make it out to be.

Proof please as I do not believe this unless mitigating factors like running downhill

You'll have to come down from the mountains to the east. Lots of guys faster than me, just cause they are not on the Internet don't mean they are not out there.

 

[YamahaTim]

I said "some guys".....maybe your not one of them. Work away on which ever belt you prefer. My stock viper has been 110.9 on the junk 8jp.
Your not the only one to clutch and test. I just think in the end if guys put as much effort into making the 8jp work as they have into the 8dn, the belt isn't as bad as everyone is trying to make it out to be.

I don't think me or other people are trying to make the 8JP belt bad, it just is not as consistent of as durable. For me and many others that is. Who cares what belt we have to use to make the Viper a more fun sled to ride and more consistent! Anyway the 8DN is cheaper!

It's not like I had a personal problem with the 8JP and it pissed me off so I tried the 8DN. It just happened by chance and it worked! I'm not mad or diss like the 8JP...lol

Just didn't stay together and never gave me consistent rpm or speed. Plain and simple!

 

[RXVIPER]

Yamaha should of never changed the belt , stay with what works. I've never had any problems with the 8DN on previous sleds.

 

[YamahaTim]

Yamaha should of never changed the belt , stay with what works. I've never had any problems with the 8DN on previous sleds.

X2

 

[sk-rx1]

A year ago Yamaha dealers asked about a new belt for the Viper. They were concerned as the durability of the 8DN was a good selling point for Yamaha's. Yamaha assured everyone that the new belt would be the same as the 8DN, only slightly shorter. And as they said, specifications may change???????????

 

[NOS-PRO]

I agree, I have always had the 8DN yamaha belt on all my trail sled 4 strokes and even on most of my race sleds with good luck.

Anyone out there have 8JP belts they want to get rid of? My son would thank you for them. Why you may ask? I posted in this thread a couple weekends ago about my testing with the 8DN, 8JP and all the times along with clutching. Well, all the time I was using the 8DN belt from the nytro which was just broken in, I told him to put the 8JP on his sled. He did, it squealed at first so we tok out the 3 washers and it was working fine. Then he comes back by me and says he had 110 on the speedo. I didn't believe him so I took it for a ride and saw 114! I d not have the gear cut so in reality it is about 9mph off. But still, true 105mph out of a stock Nytro

SO, if any of you out there want to get rid of a 8JP belt you won't use anymore, he can put it to use.

(Still can't believe it made the damn thing faster.....)

 

[larrypolaris]

I've had good luck with the 8JP belt.
I put over 1700 miles on the belt and really no issues.

My engine always spun 8900-9050-ish rpms depending on snow conditions.

But my sled has a Hauck clutch kit that I ran on my Nytro, that I set up to work on the Viper.
Basically I took weight out of the weights to get the engine to spin in the 9000 rpm range.
The Nytro made more power and could pull a heavier weight.

With the 8JP belt I had my Viper between 100-105 mph on ideal conditions for top speed.
Ran 80-90s mph on softer snow conditions.

But after 1700 miles the belt was due for a change. You could tell.
I always change my belts at around 1500 miles anyhow.
Mostly because there are some performance losses and they make for good spare belts.

I am heading to the Copper Harbor region next weekend. Plan on putting some big miles on.
I plan on running both belts and do some real world testing.
Just to see for my own benefit.

Whatever belt I feel performs the best I will run.

Just like all of us. We are all looking for that little bit of edge.

 

[stingray719]

I agree, I have always had the 8DN yamaha belt on all my trail sled 4 strokes and even on most of my race sleds with good luck.

Anyone out there have 8JP belts they want to get rid of? My son would thank you for them. Why you may ask? I posted in this thread a couple weekends ago about my testing with the 8DN, 8JP and all the times along with clutching. Well, all the time I was using the 8DN belt from the nytro which was just broken in, I told him to put the 8JP on his sled. He did, it squealed at first so we tok out the 3 washers and it was working fine. Then he comes back by me and says he had 110 on the speedo. I didn't believe him so I took it for a ride and saw 114! I d not have the gear cut so in reality it is about 9mph off. But still, true 105mph out of a stock Nytro

SO, if any of you out there want to get rid of a 8JP belt you won't use anymore, he can put it to use.

(Still can't believe it made the damn thing faster.....)

Mine were roasted so no good. BUT, if softer belt is giving him more speed consider the Ultimax belt for the Nytro. I am now running that on the Viper also for the different compound.