Viper RTX LE clutching

[weasel33]

500, you saw 94 on your le? How on earth did you do that? Where you going straight down hill on glare ice!! 74 top speed on mine so far. Hopefully it gets better, I'd be thrilled to see low nineties.

 

[titanrcr]

I'll kick off the discussion with a couple of observations:

The RTX has a 1.7" lug sno-x track which is stiff and pumps a lot of air. NOS PRO runs 104 mph with 153" 2.25" track which tends to neutralize this theory.

The RTX LE is geared at 21/49 (2.33) versus 24/50 (2.08) on std models. I find it interesting that the Standard and the LE hit the same wall but at different speeds.

To me this indicates that the gearing is impacting in some way. Something like clutching efficiency as the ratio shifts more deeply. Otherwise with teh gearing change, we should see the LE models pull up to max shift more quickly than other models.

My advise would be to work with your Ulmer clutch setup as supplied and not confuse things with another clutch setup. It's been tested and tuned on a track dyno and working well for many others. Make sure your primary is clean and moving freely. Make sure you deflection is set correctly, not height in secondary but actual deflection. Better tight than loose. Don't expect the LE to be as fast as a standard or SE due to lug height and gear ratio. It might be giving up close to 10 mph. Last, give the engine a chance to brake-in. Should be a noticeable difference at 800-1K miles.

 

[stingray719]

What are the stock weights on an LE? 8gl like the others or 8bu-10?

 

[500champ]

I believe they are 8gl

 

[500champ]

500, you saw 94 on your le? How on earth did you do that? Where you going straight down hill on glare ice!! 74 top speed on mine so far. Hopefully it gets better, I'd be thrilled to see low nineties.

On a lake

 

[NOS-PRO]

I thought those were geared to be a low speed ditch banger... 10mpg... what a pig.

Yup, they should have never changed the gearing IMO. 3 identical sleds, all different clutching not being able to hit 85mph.....sad.

 

[weasel33]

The weights are 8 gl. I don't mind a sled thT doesn't do a hundred but I'm looking for at least ninety. If yamaha calls this sled a snow cross sled then they should tell the dealers that this sled will only do 75 to 80 out of the box and then the dealer could tell the consumer and let us make the decision as to what sled we want to buy. If I would have known this back on feb 22 when I ordered it is would have never gotten this model. Riding in New York you may be able to get away with this model but I mostly ride in Maine and 75 mph and ten mpg just spent cut it. Also, I had a nytro rtx that was the snow cross model that did 97 mph gps all day long!

 

[cannondale27]

This is my clutches after 106mph. Stock unmachined. 8dn Dayco. Same clutching as muni. 95 in snow. No belt dust no marks. LE will have to shift out this far IF 9t drivers to get decent speed.

 

[TD Max]

So are you saying the clutching on the cheap does not work? or just not in your sled?

Right now nothing that I have works in this sled.

My impressions (top speed issues excluded)

Ulmers kit seems to have better hit and response. Seems to snap the nose up quickly and more aggressively. Better for squirting off of berms etc

COTC is a bit slower responding making the pull feel more subdued. Better for sweeping turns etc.

That said, this is all seat of the pants initial impression and I know enough from my diesel tuning to say that sometimes the slow and smooth approach is deceivingly fast. I think I need more time with this machine and fix what ails it first.

 

[NOS-PRO]

The weights are 8 gl. I don't mind a sled thT doesn't do a hundred but I'm looking for at least ninety. If yamaha calls this sled a snow cross sled then they should tell the dealers that this sled will only do 75 to 80 out of the box and then the dealer could tell the consumer and let us make the decision as to what sled we want to buy. If I would have known this back on feb 22 when I ordered it is would have never gotten this model. Riding in New York you may be able to get away with this model but I mostly ride in Maine and 75 mph and ten mpg just spent cut it. Also, I had a nytro rtx that was the snow cross model that did 97 mph gps all day long!

Yes, if Yamaha told everyone the speed of this model with this gearing, I guarantee 3 people wouldn't have bought them.

 

[stingray719]

I have the 8 tooth drivers and 41 bottom sprocket and chain from my XTX if some one wants to make there RTX an XTX gearing.

BTW just out of curiosity how much room between the heat exchanger and track with 9 tooth drivers and 1.7 track?

 

[Srxspec]

I have the 8 tooth drivers and 41 bottom sprocket and chain from my XTX if some one wants to make there RTX an XTX gearing.

BTW just out of curiosity how much room between the heat exchanger and track with 9 tooth drivers and 1.7 track?

Stingray, your XTX 8 tooth drivers are 3.0 pitch. The RTX & LTX models are 2.86 pitch, so you can't swap out the drivers you have (would hate for you to send parts somewhere to find out they won't work).

1-1/4" of clearance from edge of lug to front exchanger with the 1.7 track.

 

[stingray719]

Stingray, your XTX 8 tooth drivers are 3.0 pitch. The RTX & LTX models are 2.86 pitch, so you can't swap out the drivers you have (would hate for you to send parts somewhere to find out they won't work).

1-1/4" of clearance from edge of lug to front exchanger with the 1.7 track.

Oh yeah I forgot about the pitch being different, but at least the gears would work.

 

[500champ]

Yup, they should have never changed the gearing IMO. 3 identical sleds, all different clutching not being able to hit 85mph.....sad.

then why is mine getting 94 mph out of the box, bone stock ?

 

[shagman]

Guys remember the Blue and White and the Blue and Orange, RTX LE's have different gearing from the factory. This post was started by TD Max and he has the Blue and white. Lower gearing and less mph possible compared to the Blue and Orange.