2015 RTX LE (Blue/White) with 1.7 track GEARING

[Bob List]

Received an email from ALLEN ULMER last night with the following info in it which was news to me, other purchasers, and my dealer.

"I have done about 15 MPI turbo installs now and have everything spot on with the clutching. On the trail MPI kits you should have no problems. The fuel controller may be set a tad on the rich side, but nothing major. i think you will be close enough that riding on the trail will be no problem whatsoever." (KICKER HERE). "They have thrown us for a loop on the Viper RTX SE 1.7 though, as they have changed the gearing drastically over what was in the 1.25 track RTX models. They have gone from 24/50 gearing in the 1.25 track sleds to 21/49 gearing in the 1.7 track sleds. This is going to keep us at 105 mph on top end with the stock gearing."
"21/49 Stock = 105 mph
22/48 (uses stock chain yet) = 111 mph
24/49 (requires use of a new chain) = 119 mph"

 

[TD Max]

Interesting

I have the 22 tooth from Ulmer, but I guess I won't need it

The next question I have is do those speed figures take into account clutch machining?

Realistically, I think 105mph sounds plenty fast for me anyhow.

 

[tapex_07]

I wonder why the gearing is low in these sleds? Compare it to the Nytro MTX . 19-20 top and 40 (I think) bottom.. 8t 3.0 drivers (same on both)... SAME MOTORS! Why can't the Viper LTX or XTX pull 24 top and 40-42 or smaller bottom with a lower shorter track?? For years the SX chassis couldn't go any bigger than 40 or 42..
Any insight would be great guys.

 

[Bob List]

I'm asking Dave Marshall about it and waiting for a reply. With any turbo and that gearing we should be getting to 105 very quickly. Unfortunately for me, I need another 10 (or better) on the top end where I trail ride, so don't mind giving up a little quickness for top end.

 

[Studroes144]

I wonder why the gearing is low in these sleds? Compare it to the Nytro MTX . 19-20 top and 40 (I think) bottom.. 8t 3.0 drivers (same on both)... SAME MOTORS! Why can't the Viper LTX or XTX pull 24 top and 40-42 or smaller bottom with a lower shorter track?? For years the SX chassis couldn't go any bigger than 40 or 42..
Any insight would be great guys.

Viper ltx and rtx use 9 tooth drivers.

 

[Studroes144]

With stock ltx/rtx gearing of 24/50 and stock 9 tooth drivers it is capable of 117mph at full shift, the same gearing with 8 tooth drivers is only capable of 109 mph at full shift out. The difference is in the drivers.

 

[tapex_07]

The XTX has 9t 3.0 drivers? Pretty sure it's 8t.. the LTX is 9t 2.8X drivers.. and a Nytro MTX is 8t 3.0. All are similar diameter (7.6" vs 8.1")

I think I'm going to try some taller gears in my XTX and see how it reacts. Unless others have and found it to be poor.. not enough snow around here yet for any real testing.

 

[Studroes144]

Rtx/ltx have 9 tooth 2.86 drivers.
Xtx has 8 tooth 3.0 drivers.
Rtx/ltx gearing is 24/50, possible top speed of 117.
Xtx gearing is 21/41, possible top speed of 116.

 

[Bob List]

It appears however that "not all RTX's are created equal" according to Ulmer (original post above). So if you happen to have a stock 2015 RTX LE Blue/White with the 1.7 track, you don't get 24/50 but rather 21/49. And it will top out at 105. I'm hoping to get more info on this next week.

 

[cannondale27]

Don't you guys get the spec sheet when you buy sled? Gearing is on there. Could you post a pic of the sheet?

 

[TD Max]

Spec sheet?

 

[cannondale27]

Yes. All the 14 spec sheets are posted in facts sticky. Would love to do 15's also.

 

[cannondale27]

Here:
http://www.ty4stroke.com/threads/factory-spec-sheets.123768/

 

[cannondale27]

If you look here a 15 RTX DX is shown. 24/50. No LE though. Look in your paperwork.
http://www.ty4stroke.com/attachments/xtx-specs-pdf.93626/

 

[TD Max]

OK found mine and confirmed 24/50.