Trying The 8DN BELT

[DeerHuntr]

Over Rev is when the machines rpm goes too high and gets out of its power band, mine is doing it continually now. I can hit the Rev limiter any time I want I just have to stop and can it off the line. Even using the 8dn I am seeing 9000 rpm allot on wide open pulls now. When this thing stays at 8800 it's a rocket but that's the bottom end of my range now. I am trying to be a cheap #*$&@ and get through this season and get a clutch kit for next year as I have allot of medical bills and am seasonally unemployed at the moment. I called the dealer yesterday, hopefully I can get Yamaha to take a look at this for me. When you pay $12k for a Sled the clutching should be closer than that IMO.

 

[NOS-PRO]

Can you explain exactly what over rev is please?

Over-rev like Deer has mentioned is out of the powerband, but also hits the rev limiter at 9,300 (results from slipping the belt)

Actually, I think Yamaha has the clutching pretty much dialed in as I am using stock components except for the helix which amazed me. The belt plays a huge part in clutching and the stock viper belt is junk for the Viper. The 8DN grabs so much better reducing heat, slipping and not hitting the rev limiter. Add so much smoother engagement and driveability.

 

[DeerHuntr]

Mine was pretty good when it was new, actually it was a little bit low, but now with almost 700 miles on it the clutching is way off, it has gotten worse in the past 200-300 miles. Not sure if it's just putting out that much more power or if I have something wrong. It's backshifting well, have never blown a belt. It seems to be working like it should but acts like it just needs more weight. Hopefully Yamaha can hook me up, I know little about actually tuning my clutches but I do know when something isn't right.

 

[Buster696]

DeerHunter, Just a suggestion… If you have $20.00 to spend go purchase a silver secondary spring (if you are running the 8dn belt) put an additional washer so that there is a total of 2 on the back of the secondary and set it to 90 (6-3) or 100 (9-1) degrees. Should lower your RPM a little

 

[DeerHuntr]

Thanks for the input Buster, waiting to hear from the dealer first. I have gotten allot of input on this already, some guys say need heal weight, some tip weight, some guys say don't mess with the secondary and some guys are like you suggesting a different spring, helix or both. I don't want to get caught up in chasing my tail if you know what I mean. I understand that there is more than one way to skin a cat but I sure get allot of varying opinions.

 

[jw440/800]

We did some track dyno runs this past weekend and we tried several different clutch/belt setups. Our finding were that the stock belt and 8DN made no noticeable difference on the track dyno. I'm not saying that they don't make a difference for others, but for the stock sled that we tested it on (650miles on it) it had no real improvement or lose. Just our testing

 

[YamahaTim]

We did some track dyno runs this past weekend and we tried several different clutch/belt setups. Our finding were that the stock belt and 8DN made no noticeable difference on the track dyno. I'm not saying that they don't make a difference for others, but for the stock sled that we tested it on (650miles on it) it had no real improvement or lose. Just our testing

That could be ver true. It may put down the same numbers, but between the two belts for me anyway the 8DN is much smoother and stopped the slipping and seems to last. It looks way better to. After a few miles the stock belt looked warm down, after same miles the 8 DN looks way better. Way less belt dust. Not really a speed or power thing, it's just way more consistent than the 8JP. IMO.

 

[NOS-PRO]

We did some track dyno runs this past weekend and we tried several different clutch/belt setups. Our finding were that the stock belt and 8DN made no noticeable difference on the track dyno. I'm not saying that they don't make a difference for others, but for the stock sled that we tested it on (650miles on it) it had no real improvement or lose. Just our testing

That could be ver true. It may put down the same numbers, but between the two belts for me anyway the 8DN is much smoother and stopped the slipping and seems to last. It looks way better to. After a few miles the stock belt looked warm down, after same miles the 8 DN looks way better. Way less belt dust. Not really a speed or power thing, it's just way more consistent than the 8JP. IMO.

I agree, I really started noticing the belt going away at 1,500 miles and really discoloring the clutches along with high temperatures. Also noticed a new (newer) viper belt helped compared to the original belt where the original belt wasn't wore that much, just burned up.

We have a track dyno here also, but I was looking to get it on there closer to April.

 

[YamahaTim]

They say its the exact same except size and I dont really believe that. I seems like the 8DN is different. But what do I know...

 

[NOS-PRO]

Compound of belt is way different....has to be

 

[YamahaTim]

Compound of belt is way different....has to be

Thats what o was thinking and I think I read somewhere that it was different. But I also seen something saying it was the same compound and I just dont see it! Im getting my sled back its done so everyone will be happy cause they wont see my name on every post anymore...lol

 

[DeerHuntr]

Well heard back from my dealer on my over reving , Yamaha told them verify belt deflection, track tension and if those check out its probably normal. They said the gauges can vary a couple hundred rpm. Pretty disappointed with Yamaha on that answer. So I guess hitting the Rev limiter is normal. Bet if it screwed up my engine they would tell me I shouldn't let it do that and to go fly a kite on that as well. Have a call in to Ulmer racing, waiting for a reply.

 

[stingray719]

They say its the exact same except size and I dont really believe that. I seems like the 8DN is different. But what do I know...

Its not the same, hold two belts together or look at my pic in previous post. Sides on 8DN have more surfae and more resistance to belt squeeze. Goes without saying belts all have different compounds, even on same belt if it is burned or not.

 

[stingray719]

Well heard back from my dealer on my over reving , Yamaha told them verify belt deflection, track tension and if those check out its probably normal. They said the gauges can vary a couple hundred rpm. Pretty disappointed with Yamaha on that answer. So I guess hitting the Rev limiter is normal. Bet if it screwed up my engine they would tell me I shouldn't let it do that and to go fly a kite on that as well. Have a call in to Ulmer racing, waiting for a reply.

If you have the 8DN on and still over revving you can do what is not the best solution but acceptable. Decrease spring pressure on the secondary and you can get 200 to 300 rpm easy. Also increases upshift rate which may also help you. Here in the high country I wind our secondaries tight to cause slow upshift and quick backshift at the cost of top speed because we don't care about top speed in the trees.

Just grab your favorite 12mm socket and rachet and take the 3 helix nuts off. Set spring one or two less than now and put helix back on....easy! Oh yeah taking belt off first is wise.....lol. Quick and easy free test!



Secondary numbers add to angle, 6 on helix and 1 on secondary = 70. 3 on helix and 1 on secondary = 40...etc. I suspect yours might be on 70 (6+1).

Let us know if you tried it and if it solved your problem!

 

[NOS-PRO]

Well heard back from my dealer on my over reving , Yamaha told them verify belt deflection, track tension and if those check out its probably normal. They said the gauges can vary a couple hundred rpm. Pretty disappointed with Yamaha on that answer. So I guess hitting the Rev limiter is normal. Bet if it screwed up my engine they would tell me I shouldn't let it do that and to go fly a kite on that as well. Have a call in to Ulmer racing, waiting for a reply.

If you have the 8DN on and still over revving you can do what is not the best solution but acceptable. Decrease spring pressure on the secondary and you can get 200 to 300 rpm easy. Also increases upshift rate which may also help you. Here in the high country I wind our secondaries tight to cause slow upshift and quick backshift at the cost of top speed because we don't care about top speed in the trees.

Just grab your favorite 10mm socket and rachet and take the 3 helix nuts off. Set spring one or two less than now and put helix back on....easy! Oh yeah taking belt off first is wise.....lol. Quick and easy free test!



Secondary numbers add to angle, 6 on helix and 1 on secondary = 70. 3 on helix and 1 on secondary = 40...etc. I suspect yours might be on 70 (6+1).

Let us know if you tried it and if it solved your problem!

Stingray - Are you running a cat clutch with the 10mm nuts? Cause my nuts are 12mm

Just giving ya crap bud!

Good info and I would agree with stingray on the "change" to your stock components.....it's free, just have to get your hands dirty