Clutching: what to do

[ViperRTX-Turbo009]

I have a 15 rtx le, regeared it, added 2 teeth to the bottom gear and did the chain. I have a hurricane clutch kit and turbo setup.

My question is, when on hard pack the sled revs up to 8900 hits over 100 mph, that's ok I'm happy with that. But get into some loose snow and it'll rev up to about 8700 or so off the take off maybe 8800 hard to tell with the shirty tagh, but then it's instead of pulling it falls flat on it's face at80 mph at max like 84/8500 rpm- is this a secondary clutch issue ?!8/ it opening up to fast ? I still have the 139 x 1 3/4 track, but honestly it should have the power to pull something better... Any one have a issue like this ?

 

[TD Max]

What was your stock gearing? Assuming you started with 24/50 and you went to 24/52 you hit a solid middle between at 2.16 versus 2.08 and 2.33.


Sounds similar to what the RTX LE is seeing with it's 2.33 chain ratio.

Right now the answer has been to gear the sled faster to what you likely have, but this is treating the symptom and not the cure IMHO.


I am hoping we can find a clutching solution. I'm thinking we need a helix change to slow the shift.

 

[MrSled]

Are you running a 8DN belt?

 

[Yamadog]

Mine was having a similar problem Friday night. I was racing several XF1100's on fresh snow on a lake not groomed. It would leave like crazy but fell flat on its nose at 100 mph when I was easily seeing 112 on the trail earlier in the day. I raced at the Minocqua drags on Saturday and put a new 8dn on instead of the 8 jp that had about 700 miles on it and she went back to 109 outside the race and did 101.83 in 660 ft on the track but my skis were 2' in the air for the whole trip taking away a bit of my top end.

 

[MrSled]

Mine was having a similar problem Friday night. I was racing several XF1100's on fresh snow on a lake not groomed. It would leave like crazy but fell flat on its nose at 100 mph when I was easily seeing 112 on the trail earlier in the day. I raced at the Minocqua drags on Saturday and put a new 8dn on instead of the 8 jp that had about 700 miles on it and she went back to 109 outside the race and did 101.83 in 660 ft on the track but my skis were 2' in the air for the whole trip taking away a bit of my top end.

8jp is usually the problem... that happened to me and now that I use the 8dn on the turbo it wont drop like that.

 

[titanrcr]

I have a 15 rtx le, regeared it, added 2 teeth to the bottom gear and did the chain. I have a hurricane clutch kit and turbo setup.

My question is, when on hard pack the sled revs up to 8900 hits over 100 mph, that's ok I'm happy with that. But get into some loose snow and it'll rev up to about 8700 or so off the take off maybe 8800 hard to tell with the shirty tagh, but then it's instead of pulling it falls flat on it's face at80 mph at max like 84/8500 rpm- is this a secondary clutch issue ?!8/ it opening up to fast ? I still have the 139 x 1 3/4 track, but honestly it should have the power to pull something better... Any one have a issue like this ?

I believe your RTX LE came stock with a 2.33 ratio and now you have added two teeth on the bottom? That should put you at around a 2.42 ratio, most people would go the other way with gearing for more speed, especially with a turbo. Not surprised it's falling on it's face, with that ratio your getting into the shallow angle of the helix early where the shift slows down.

 

[Yamadog]

I am just cheap and wanted to run that belt till it popped. Since Ulmer did my clutches and set my sled up I have not broken another 8jp. I used to get 150 ish miles out of them and that one was over 700. It will now be a spare.

 

[ViperRTX-Turbo009]

Ok well stock gearing on the le was 21/49 correct , I am currently running 21/51 (dealer said this would be good to get me up to 100 mph and over) at this oijnt I'm debating just putting the stick gears back in.. I had it running 8900 rpm at 95 mph which is faster than I'm seeing now tho there want reall much snow on the lake when I was doing that, I'm not so worried about top speed but always thaught 190 hp would still pull a 100 mph- granted I bet looked into gearing really just went with the advice of the dealer since I was getting some warantee work done..

Anyways tho what I did doesn't sound like a good option from what I'm hearing , seeing as how I never put the clutch kit on to begin with I'm not sure exactly what's in there but the secondary spring wrap appears to be 6 and 1 and I've tried a couple diffrent primary's springs - not helping much.


If I changed the spring in the to engage at like 4000 rpm would that do anything - roughly what spring would that be? I'm engaging rough 36-3700
Right now , good launch but falls flat on it's face at 75. Creeps up to 80 in the snow , but only 8400 rpm . It only went to 8100 one time, and it's sad when my buddy in a bone stock rev 800 rips past me ...

So anyone know of a easy fix or should
I just slap the stick gears in it and just ride it and play again next year ? We finially got some snow I just want it to rev up and rev properly , honestky can live with 90 mph just the thaught of 100 plus sounded good -

 

[ViperRTX-Turbo009]

Again never had a yamaha - played with lots of ski doo clutches but this ain't no ski doo... Any input would be great- dealer is not will long to help me unless I hand I'm handfuls of cash so ...

 

[titanrcr]

Yes, at the very least put the stock gears back in. Bad poop from the dealer...

 

[TD Max]

I would either put it back to stock for now or just wait. There are two identical non turbo LE Vipers running right now with their gears changed from 21/49 to I believe 22/50 and 24/50. They should rack up over 1000 miles on this trip and should have some good feedback.

 

[ViperRTX-Turbo009]

Ok thanks guys .. Let me know... I'll prb out the stick gears back in for now , keep me posted on some set up options ... Not opposed to spending more money , just not having a good go with my dealer .... Im just looking to hit 100 mph - I'm more of a in the bush rider anyways - but a 100 mph plus would be nice , want to keep the 1 3/4 track tho , love the hookup

 

[ViperRTX-Turbo009]

Td max what are you running ?

 

[ViperRTX-Turbo009]

Question if I go back to stick gears I'm running the 8dn bent , if I machine the clutches, would that take me to 100 mph ? Anyone do this on the le?

 

[Yamadog]

Well at first make sure you have the secondary wound correctly there is a thread on here about that. 2nd change to 8 dn belt all you need is to add 1 washer to each of the 3 adjuster bolts found on the back side of the secondary. 3rd there is a problem with spring bind on the secondary at full shift out that can be fixed by someone like Allen Ulmer. 4th are you running gauges? boost and AFR? do you know for sure what #'s of boost your are running?

My sled last year at 9 #'s of boost or about 210 hp would still barely turn 100 mph. I was disgusted and upset cause I had already popped a motor. I was going to sell it. Then I decided to go with Allen and dropped it off at his shop. We added 4th injector fixed all the problems from original build by Hauck and a bunch of broken parts and moved the boost switch from 7 & 9 to 9 & 12#'s. He threw away Hauck's overdrive sheave, helix and clutch kit and started over. Machined the secondary to eliminate spring bind and put the proper helix in it, machined both sheaves on the primary for overdrive not 1 like Hauck so the belt stays centered and then set the clutches on the track dyno. It did 117 on the dyno at 252 hp. So far I have hit 112 and still had more but ran out of room. I am still on the stock XTX gears which are much lower than yours.

The Tachs do suck on these but the speedometers are dead on. at the radar run (660 ft) Saturday I crossed the line with the speedometer saying 103 and the time slip was 101.83. That is pretty darn close. A 320 HP D&D XF1100 with a driver 50 lbs lighter than me only got 101.95