All day Viper Clutching..

[titanrcr]

I'm almost afraid to ask, what belt does Excell run, 8JP or 8DN ?

 

[MrSled]

I'm almost afraid to ask, what belt does Excell run, 8JP or 8DN ?

8DN

 

[wot-75]

The XS805 is the equivalent to the 8DN. We had to run way less weight and less helix wrap to get it to perform equal to the 8DN. This is because the XS805 is softer and really pulls down the rpm. Ulmer sets up his kits for the 8DN.

Do you think the Gates belt will behave similarly to the XS?

 

[tator]

i run the gates and see the rpm low. i took some weight out of the tip and still low. in MI i tightened the secondary to get it up. but it robbed some on top. i need some snow to do testing at home and get it sep up right. or go back to the 8dn. i dont have any belt dust or slip with the gates and 1000 on the belt so far. want to loosen the secondary and take weights out but i need snow! the loosest the secondary can run, without slippage, the best i would think for a good performing setup. especially for top speed. im no expert but just trying to think what is keeping me under 110. pulls great to 95 then climes good to 102 then slow climb after that on great conditions. on trail conditions it ends at 105. thinking the 8dn is the best belt for all. and available everywhere.

 

[MCApex44]

Thanks for taking the time to do this!

 

[larrypolaris]

Great job guys and thanks for all your work and efforts.

Great information.

 

[Buster696]

Tom, thanks for all the info and straight-talk on this. I have a similar setup with Excell and the stock Yamaha weights find the fun factor the same as you. I do have my clutches done by Ulmer, so maybe, I have the best of both worlds.





--Buster696--

 

[MrSled]

Tom, thanks for all the info and straight-talk on this. I have a similar setup with Excell and the stock Yamaha weights find the fun factor the same as you. I do have my clutches done by Ulmer, so maybe, I have the best of both worlds.





--Buster696--

Right on brother

And everyone else... you are welcome. If I can get more time in a few weeks I will post more info. I am going to try and get NosPro and Cannondale over maybe even Shagman if he can make it for a test and tune session to experience what they have been doing.....if anyone else is in my area, you are all welcome to join.

 

[TD Max]

Keep us in the loop. I'd like to top 90 mph some day...

 

[1tp]

Tom's sled (2015 XTX) has the Excel intake and exhaust on it. COTC with that sled did have a very nice low engagement and the pull to top speed was very linear. Very very smooth setup. If I recall, top rpm was around 9200 with a top speed of about 97-98. Ulmer's kit had a higher engagement speed with a better low and mid range pull. Top speed was 100 with an rpm of 9300. But we all felt the best setup on this sled was Excel's kit. Low and mid range felt the best and it pulled 100mph right at 9000 rpm.

The two short tracks were both RTX SE models. One was a 2014 with a Cobra track and still using the 2014 map (no reflash on this sled). The other was a 2015 RTX SE with the Ripsaw 2. These sled both have Ulmer's clutch machining done on them and have his clutch kit and exhaust. We started out on both of these using the Ultimax XS805. Which when tweaked for that belt had a great low and mid range pull. And topped out at 100 with around 9000rpm. We then switched one sled to the 8DN belt just to see the difference - and WOW was a difference. We changed nothing on the clutch setup other than the belt. When switching to the 8DN, we could only get about 70mph out of it. Any more and it would overrev drastically. That told us the setup needs to be completely difference for the 8DN. So changed the 2014 model setup back to Ulmer's recommendations (as the kit comes setup from him) and bang - 100mph at 9000rpm with great low and mid range.

Drag race - Two RTX SEs ... one with Ulmer's recommended setup, 8DN and Cobra, the other with our tweaked Ulmer setup, XS805 and Ripsaw 2. Wouldn't you believe it .. the two were dead even from stop to top speed. They were both even from a roll-on start to top speed. If any sled had an edge, I'd say the Ripsaw had a bit better traction.

The vendors that offer their kits put a lot of time, effort and money in coming up with what they provide. What we found is that if you have mods other than the clutch kit (such as intake or exhaust), their clutch kit seems to work best with their mods. Example - Excel's clutching worked best with Excel's intake and exhaust. All of these kits can be made to run the way YOU want them to. Some extremely smooth, others have great mid range and low end. But ALL can be made to run 100mph. My only recommendation is use whatever kit you want. Use whatever Vendor or setup you like the best. In the end you will likely be happy.

Did you bang the rev limiter on any of these set ups when launching from a stand still or rolling (20mph) start?

 

[MrSled]

Did you bang the rev limiter on any of these set ups when launching from a stand still or rolling (20mph) start?

Not that I am aware of... but on my XTX, my rev limiter is at 9600 with my ignition module from Dyno Jet. And even after letting her scream with my RPMs, it did not gain any more speed in the conditions we tested.

 

[Turtle]

Did you bang the rev limiter on any of these set ups when launching from a stand still or rolling (20mph) start?

Neither of the RTXs hit the rev limiters during our drag racing.

 

[Turtle]

Not that I am aware of... but on my XTX, my rev limiter is at 9600 with my ignition module from Dyno Jet. And even after letting her scream with my RPMs, it did not gain any more speed in the conditions we tested.

This is something that we discussed during our testing session. It proved that just simply getting the RPM higher doesn't always give you a higher top speed. If you get a higher rpm, then you need to make sure your clutch can pull the same ratio. We had some runs where the RPM went higher, but the top speed was lower - proving that we weren't getting a higher drive ratio out of the clutches. Think of it as riding a 10-speed bicycle in first gear. You can pedal as fast as you want, but your top speed is going to be slow.

 

[1tp]

This is something that we discussed during our testing session. It proved that just simply getting the RPM higher doesn't always give you a higher top speed. If you get a higher rpm, then you need to make sure your clutch can pull the same ratio. We had some runs where the RPM went higher, but the top speed was lower - proving that we weren't getting a higher drive ratio out of the clutches. Think of it as riding a 10-speed bicycle in first gear. You can pedal as fast as you want, but your top speed is going to be slow.

Did you bang the rev limiter on any of these set ups when launching from a stand still or rolling (20mph) start?

Thanks

 

[cannondale27]

This is something that we discussed during our testing session. It proved that just simply getting the RPM higher doesn't always give you a higher top speed. If you get a higher rpm, then you need to make sure your clutch can pull the same ratio. We had some runs where the RPM went higher, but the top speed was lower - proving that we weren't getting a higher drive ratio out of the clutches. Think of it as riding a 10-speed bicycle in first gear. You can pedal as fast as you want, but your top speed is going to be slow.

This in my opinion is the statement of the day. Now if you can pull the same or heavier weight to that higher rev limit you will go faster. Problem is none of us can at least not consistently. Only solution is power and more of it. Another possibility is belt slipping.