Got a call from Chuck last night. They are up in Maine riding. Odometers are in the 800 miles range now. Identical sleds with the exception of gearing and clutching. Here are the details to the best of my recollection:
Sled 1 re geared to 24/50 2.08 ratio COTC clutch kit with 3.6g in tip, Crosstour windshield and mirrors, Dupont slides, otherwise stock
Sled 2 re geared to 22/50 2.27 ratio Ulmer clutch kit, Crosstour windshield with mirrors, Dupont slides, otherwise stock. note: 50# additional rider weight
Neither sled has a distinct speed advantage. On one occasion sled 1 pulled slightly more mph. On another sled 2 pulled slightly more. Side by side launches are pretty much even. I believe max speed was 84 mph on a fresh groomed trail that had frozen overnight, first thing in the morning. 2014 RTX was running 94 mph I believe in same conditions. Just drives on by both sleds.
MPG started about 13 has come up to about 15 and again almost even sled to sled with a slight advantage to the lighter rider.
Sled 1 is hitting rev limiter on the big end. Also major issues with high and jerky engagement. Had to follow groomer for a spell and couldn't maintain 4-5 mph. Had to stop and restart repeatedly. I suggested he drop the 2 shims from his primary to hopefully help on both counts. His experience with this mirrors mine.
Sled 2 is running in the 8800 RPM range. Engagement much smoother and manageable.
It sounds like both are leaving almost 3/4" of the sheaves unused on sled 1 at least. Neither is machined for extra OD.
We also discussed snugging up the track a bit as a test. The protectors on mine looked spotless until I took the skid out and saw they were totally smeared black up front. Manual says 20# force and 2" gap. I went with 1.5" gap on mine but have yet to test. The track is no doubt heavier. and would tend to droop more naturally.
Sled 1 re geared to 24/50 2.08 ratio COTC clutch kit with 3.6g in tip, Crosstour windshield and mirrors, Dupont slides, otherwise stock
Sled 2 re geared to 22/50 2.27 ratio Ulmer clutch kit, Crosstour windshield with mirrors, Dupont slides, otherwise stock. note: 50# additional rider weight
Neither sled has a distinct speed advantage. On one occasion sled 1 pulled slightly more mph. On another sled 2 pulled slightly more. Side by side launches are pretty much even. I believe max speed was 84 mph on a fresh groomed trail that had frozen overnight, first thing in the morning. 2014 RTX was running 94 mph I believe in same conditions. Just drives on by both sleds.
MPG started about 13 has come up to about 15 and again almost even sled to sled with a slight advantage to the lighter rider.
Sled 1 is hitting rev limiter on the big end. Also major issues with high and jerky engagement. Had to follow groomer for a spell and couldn't maintain 4-5 mph. Had to stop and restart repeatedly. I suggested he drop the 2 shims from his primary to hopefully help on both counts. His experience with this mirrors mine.
Sled 2 is running in the 8800 RPM range. Engagement much smoother and manageable.
It sounds like both are leaving almost 3/4" of the sheaves unused on sled 1 at least. Neither is machined for extra OD.
We also discussed snugging up the track a bit as a test. The protectors on mine looked spotless until I took the skid out and saw they were totally smeared black up front. Manual says 20# force and 2" gap. I went with 1.5" gap on mine but have yet to test. The track is no doubt heavier. and would tend to droop more naturally.
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SRXracer
Expert
The real question out of that is why does the '14 RTX just ride by? What's the gear ratio in that one?
I keep wondering - even at the 2.08 ratio, that is an incredibly low gear ratio compared to other sleds - apex's, srx's, etc. My apex ratio geared down 1 tooth from stock was 1.65. I then geared it down 2 teeth from stock to a 22 top, and it was 1.72. I know there is a slight adjustment factor for going to the different track drivers, but I don't think it's that much?? What about trying something like a 24/46, that would put you at about 115 theoretical speed without OD. I'll pull this into a separate thread.. but just wanted to get it out there for some feedback on this one.
I keep wondering - even at the 2.08 ratio, that is an incredibly low gear ratio compared to other sleds - apex's, srx's, etc. My apex ratio geared down 1 tooth from stock was 1.65. I then geared it down 2 teeth from stock to a 22 top, and it was 1.72. I know there is a slight adjustment factor for going to the different track drivers, but I don't think it's that much?? What about trying something like a 24/46, that would put you at about 115 theoretical speed without OD. I'll pull this into a separate thread.. but just wanted to get it out there for some feedback on this one.
sk-rx1
TY 4 Stroke Guru
Drivers do make a significant difference. A 9t driver with a 2.52 pitch (Apex) is a lot smaller than a 9t driver with 2.86 pitch (Viper)
The ratio of sled 1 and the '14 RTX are identical. The key difference is the track and probably miles.
What gets me is that a 141" 1.6 or larger lug can run fast it's just the RTX LE that seems to be exceptionally slow.
I'm hoping to get some more miles but I also want to try a helix change to something less aggressive and then maybe weight up as necessary.
What gets me is that a 141" 1.6 or larger lug can run fast it's just the RTX LE that seems to be exceptionally slow.
I'm hoping to get some more miles but I also want to try a helix change to something less aggressive and then maybe weight up as necessary.
SRXracer
Expert
One of the yamaha engineer/tech guys at one of the first shows when they introduced the viper said to me that the 141 track would be faster than the shorter ones. Bigger circle to reduce drag, and more inertia once moving. It's a nice theory, but I sort of think that's splitting hairs.
stingray719
TY 4 Stroke God
Sled 1 has some mechanical issue that is causing high and jerky engagement not seen in almost all other COTC installs. Ask him if they can put a primary from another Viper on and test.
It's acting exactly like mine does. Upper 3's engagement and jumps in. It acts like it's hanging on the ever so slight little "hump" in the weight profile at the base.
stingray719
TY 4 Stroke God
Did you get a chance to try a known good working primary clutch on yours to test?
He did. Felt fine to me. Very smooth never felt anything odd. TD may have a different opinion but I never heard any complaint about engagement till now. I got 92mph out of TD's sled with more RPM left before rev limiter. TD got 88mph I believe. I was doing 99-103mph the same day same spot on my modded RTX SE. With NosPros clutches on TD's sled it came within 1/8 in or less of the top of primary. Better conditions and hold it tight longer and it could have gotten more. Maybe that track is a killer on the RTX LE. This sled is a big sissy right now and demands perfect conditions and alot of balls to get everything out of it. Like a race 2st. Maybe those guys looking to complete a big mile trip didnt have the balls or conditions to hold it tight. I wouldnt on a big miler. Too much risk of ruining a trip.
weasel33
Expert
No cannon I have the balls to hold it wide open even on a big trip. I held it wide open for around six to eight miles on a perfectly groomed rr bed and only got 84 mph out of it. So did my brother. As well as many other times trying to find top speed and top rpms. That's pretty ballsie saying that knowing that I read on this site pretty often. Do you know me and how I ride?
Sorry if it came out that way but nothing was said of distance or whether or not you did in fact hold it tight. I stand corrected and I am sorry. So why is just that track keeping you at 84mph? Does not make sense.
weasel33
Expert
Ok I just want you to know that I won't say or post something with first testing what I say.
Of course I trust ya. Alot of us are all frustrated here. I have seen firsthand claims made on both ends of spectrum. Low and high speeds and have seen the cause of some of it. Some of it is just plain not holding it tight and some of it is conditions/distance as far as high speeds and low. It doesnt take a rocket scientist to figure out a average speed. We all look. So now we have to figure out why yours with the same gearing is way slower on top than a RTX SE. Willing to do a clutch swap with that RTX? Would be easiest and fastest true test. If same results ditch that track and run a Cobra.
stingray719
TY 4 Stroke God
Sorry if I am a little dense here, but with NOS-PRO clutches on TD sled did it act correctly on the engagement?
Seemed fine to me. Smoother than stock for sure.
