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And a good time was had by all...

Depends on what is offered. Trying to get ahold of EVO. They have gears and I would prefer to just go one tooth bigger on top. So a 25t. If not will probably go with XTX gearing.
 

25/50 will not fit with the 92 link chain. You're better off going with a 48 bottom gear, 24/48 will work with your stock chain.
 
aquaticlaker said:
Thanks to all! My son and I had a great time seeing what was going on and learning many things. What a great group of guys and girls that were there to help with anything.

First thing we did was take out the Viper LTX SE for a run down the railroad grate. Stock everything. Consistantly ran 96mph GPS. My son ran a stock 2006 Attak with 11,000 miles on at 101mph. We started testing the COTC on the Viper and kept hitting the rev limiter hard. After 4hrs of testing we saw a speed drop do to hitting the limiter. Never got where we needed but, with all the learning from yesterday I can now make the appropriate adjustments. Not sure if I will be able to get faster with COTC but, it will be fun trying.


Special Thanks to NOS PRO!
Click to expand...

You are very welcome Mike and you WILL be faster once we get you off of the rev limiter....it's hitting it very hard.

This was a good experiment for me as Aquaticlaker's sled is bone stock 15 Viper LTX. I put in the COTC setup and thinking of the mods he DOESN'T have.... I figured out he would be right around 100mph and 9100 rpm, yeah right......I was in disbelief when he told me he was hitting the rev limiter. So I added tip weight as Mike told me he was running 9280 on the tach. Once again he comes back and says 9280....WTF??? Now I take apart the clutching and put in 4.5 grams in the tip and he comes back and says 9270.... WOW! Just can't believe his sled is taking more weight then mine is.... Day was getting late and Mike needed to get going so we tried a Gates belt to see if it would grab better and stay off of the rev limiter....nope. I gave Mike some 3.0 gram rivets to put in the middle hole which will help him but I think his sled is THE best running stock sled out there right now for a 15 model.

Mike, when you get that rivet installed, let me know how it runs bud :)
 
TD Max said:
I should probably add that last run for my sled before loading up terry managed 94 mph in a perfect tuck.

Question: What were the "normal" non turbo sleds running for MPH out there? 101mph I believe? Would they hold this once achieved or would they drop 3-4 mph and pick back up as the icy patches were replaced with snow etc?
Click to expand...

Yes, I was in a very tight tuck and managed to see 94 on the speedo, saw TD's GPS in the pouch and was hoping it was going to say the very same thing, but don't think it was on or ?

Anyway, TD, that sled is rockin pretty good for what it is geared for and hoping to get Weasels sled running the same now.
 
NOS-PRO said:
Yes, I was in a very tight tuck and managed to see 94 on the speedo, saw TD's GPS in the pouch and was hoping it was going to say the very same thing, but don't think it was on or ?

Anyway, TD, that sled is rockin pretty good for what it is geared for and hoping to get Weasels sled running the same now.
Click to expand...


My GPS is a Nuvi and does not record top speed. It shows instant speed, but to read it on the run is tricky. What I will say is that I have been able to verify that it matches the speedo at numerous different speeds in the past.

The thing we still need to do is get rid of the slipping up top. Ulmer has a plan that Tom and I plan to test soon.
 
Last edited:
cannondale27 said:
Why do I come up with 108 using this calculator stock? At 9230rpm?
http://www.turboaddictionparts.com/catalog/snowmobilecalculator.html

XTX gearing in mine should give 114mph according to that.
Click to expand...
That calculator is correct in it's math, but it assumes a 100% efficient (1:1) clutch ratio - which is impossible for Yamaha unless you have both the secondary and the primary machined for it. Many have had the secondary machined by someone like Ulmer to accommodate the 8DN belt. But that machining alone will at best get you to 95% efficiency on the clutch, which calculates to 103 for top speed using your stock gearing.

If you use the XTX gearing at 95% eff, your top speed calculates to 109 mph ... 115 mph at 100% eff.
 
TD Max said:
My GPS is a Nuvi and does not record top speed. It shows instant speed, but to read it on the run is tricky. What I will say is that I have been able to verify that it matches the speedo at numerous different speeds in the past.

The thing we still need to do is get rid of the slipping up top. Ulmer has a plan that Tom and I plan to test soon.
Click to expand...

TD did you try different belts?
 
TD Max said:
No we stuck with the tried and true 8DN. Belt would be a consideration after we have exhausted other options.
Click to expand...
Ya know - That might not be a bad idea. My setup is tuned to run the Ultimax XS805. In previous testing, we found that the clutch setup needed to be entirely different than a setup for the 8DN. At the end of the day, each setup tuned for the specific belt resulted in the same performance. However, in your case TD, the XS805 might be a good fix to the belt slipping at WOT you are seeing ... but the clutch setup would definitely have to change to accommodate the much softer compound of the XS805.
 
Steve,
Figure out how much of a step you'd like to take for gear change.

24/50 is 2.08 ratio

24/48 is 2.00 ratio about a 4% change so in theory about 4 mph faster (not sure about chain selection with this I made it up)

21/41 is 1.95 ratio and stock XTX gearing about a 7 % change so in theory 7 mph taller

For contrast my 2.33 gearing is about 11% shorter than 2.08.

I would suggest finding a 21/41 setup like Bill was looking to sell and see if you gain speed.
 
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