Top speed is 70mph

[stingray719]

You may just want to try and change your drivers to 8 tooth and keep the same gearing. This will get you mid 80's and more efficient spin of the track which nets better fuel economy.

The 21/41 gearing tends to be a belt burner with long tracks. Doesn't have enough gearing when the snow gets thick and actually takes some power to sling.

Our Viper ran last year with a 153 Powerclaw on an XTX with 21/41 gearing. No belt burning with our clutching and I did gear it down this year only because I already had it apart to put an even bigger Powerclaw on. Not saying what you said is not possible but curious, was your experience first hand on the belt burning and gearing too high?

 

[loudelectronics]

I was running a 162 Camo 2.5" track with 21/41 and 8 tooth drivers. With stock helix and spring it would eat a belt on every climb and would not hold RPM worth a shnit. This is with the 8BU weights, 14.5 rollers and gwg primary spring and also tried stock spring. The 8DN belt helped a ton. Just on any climb where the sled needed RPM the belt would burn up.

Now with the 8DN, 8bu, gwg, 14.5 rollers, white spring and 39* helix, 21/49 gearing the sled holds rpm so much better and no more burning or exploding belts. With gearing change the sled holds rpm everywhere. If just bombing around, the 21/41 is fine but if you have to work the sled at all in lots of on/off throttle and climbing, the efficiency just is not there. This is with turbo even so HP is not the problem.

Everybody had different riding habits so what works for some does not work for someone else. I could see the stock xtx setup working fine for lots of people. Just saying the risk is there if not careful. I am not sure what you are running for clutching so again it might have made a world of difference for your riding style.

In this guys case, it is pretty easy to just change the drivers for the least amount of dough as rpm might fall to 8600-8800 which is in the meat of the power curve so it could likely work just fine.

 

[shagman]

I was running a 162 Camo 2.5" track with 21/41 and 8 tooth drivers. With stock helix and spring it would eat a belt on every climb and would not hold RPM worth a shnit. This is with the 8BU weights, 14.5 rollers and gwg primary spring and also tried stock spring. The 8DN belt helped a ton. Just on any climb where the sled needed RPM the belt would burn up.

Now with the 8DN, 8bu, gwg, 14.5 rollers, white spring and 39* helix, 21/49 gearing the sled holds rpm so much better and no more burning or exploding belts. With gearing change the sled holds rpm everywhere. If just bombing around, the 21/41 is fine but if you have to work the sled at all in lots of on/off throttle and climbing, the efficiency just is not there. This is with turbo even so HP is not the problem.

Everybody had different riding habits so what works for some does not work for someone else. I could see the stock xtx setup working fine for lots of people. Just saying the risk is there if not careful. I am not sure what you are running for clutching so again it might have made a world of difference for your riding style.

In this guys case, it is pretty easy to just change the drivers for the least amount of dough as rpm might fall to 8600-8800 which is in the meat of the power curve so it could likely work just fine.

The reason you could not hold RPM's with the 8bu weights is they don't have enough force under heavy load at full shift and belt slips creating heat and destroying belt. You needed more force at the tip. I tried them and had same result under load. Just my 2 cents.

 

[stingray719]

I was running a 162 Camo 2.5" track with 21/41 and 8 tooth drivers. With stock helix and spring it would eat a belt on every climb and would not hold RPM worth a shnit. This is with the 8BU weights, 14.5 rollers and gwg primary spring and also tried stock spring. The 8DN belt helped a ton. Just on any climb where the sled needed RPM the belt would burn up.

Now with the 8DN, 8bu, gwg, 14.5 rollers, white spring and 39* helix, 21/49 gearing the sled holds rpm so much better and no more burning or exploding belts. With gearing change the sled holds rpm everywhere. If just bombing around, the 21/41 is fine but if you have to work the sled at all in lots of on/off throttle and climbing, the efficiency just is not there. This is with turbo even so HP is not the problem.

Everybody had different riding habits so what works for some does not work for someone else. I could see the stock xtx setup working fine for lots of people. Just saying the risk is there if not careful. I am not sure what you are running for clutching so again it might have made a world of difference for your riding style.

In this guys case, it is pretty easy to just change the drivers for the least amount of dough as rpm might fall to 8600-8800 which is in the meat of the power curve so it could likely work just fine.

I have to agree with shagman, I do not like weights with a lot of curve as they force upshift and the ones that are light on the tip I like even less. Can they work? Of course they can but my preference and testing sends me back to flat profile weights loaded heavy in the tip. But like you said we all ride different.

 

[2009RSVentureGT]

Lots of great info from all of you...it is much appreciated . When you refer to the drivers....does that mean the sprockets that drives the track? The type of terrain up here is lots of back roads that go for miles and miles, power lines, trails and lake crossings...some are 20 miles across and when you encounter slush the 2.6 lug on the track sure helps. So all in all my riding will be mostly on the flat with the odd hill here and there.

 

[Mountaintech]

When you refer to the drivers....does that mean the sprockets that drives the track?

Correct.

 

[stingray719]

Lots of great info from all of you...it is much appreciated . When you refer to the drivers....does that mean the sprockets that drives the track? The type of terrain up here is lots of back roads that go for miles and miles, power lines, trails and lake crossings...some are 20 miles across and when you encounter slush the 2.6 lug on the track sure helps. So all in all my riding will be mostly on the flat with the odd hill here and there.

Drivers you have to remove your track and press drivers on and off, not sure why anyone would go through that when you can simply change gears.

 

[N2DEEP]

Just changed from stock 21-49 and installed 21-41 I have the mtx 153 2.6 track and mpi at 5 psi with full Ulmer clutch kit and overdrive machining. I went from 85 mph at 9050 rpm to 85 mph at 8850 rpm gained nothing for speed wtf. Now I'm lost ???

I want 100 mph top track speed. The top speed I run at is around 90 mph, don't want to run to the bar down the lakes. This worked perfect for my 162 2.5 apex mtx and had zero isues

 

[shagman]

Just changed from stock 21-49 and installed 21-41 I have the mtx 153 2.6 track and mpi at 5 psi, I went from 85 mph at 9050 rpm to 85 mph at 8850 rpm gained nothing for speed wtf. Now I'm lost ???

I want 100 mph top track speed. The top speed I run at is around 90 mph, don't want to run to the bar down the lakes. This worked perfect for my 162 2.5 apex mtx and had zero isues

What are you running for clutching?

 

[N2DEEP]

Primary spring PGP stock rollers 60y weight heel 2.0 mid 0 tip 4.0
Secondary spring red helix h spring wrap 6-2

Going too take a couple out on the tips to get back to 9050 rpm

 

[shagman]

Nos-pro extended his xtx to 153 x 2 1/4 without turbo and 21/41 and pulls over 90. It in your clutching. Big gains to be had there. I'm running 6 lbs with my xtx and have seen 114. Read clutching posts on here or pm me and I will help you if wanted.

 

[shagman]

Ulmer should be able to help also as it's his kit.

 

[N2DEEP]

Nos-pro extended his xtx to 153 x 2 1/4 without turbo and 21/41 and pulls over 90. It in your clutching. Big gains to be had there. I'm running 6 lbs with my xtx and have seen 114. Read clutching posts on here or pm me and I will help you if wanted.

What size drivers are the xtx's running. I have installed the xtx gears and clutches set up for the turbo and I lost speed. The best I got it is just off the limiter and 83 mph. Clutching is good but I can't see how I drop 7 teeth on bottom gear and I gain nothing. The belt is 1/4" from the top on wot

 

[shagman]

Xtx are 8 tooth.

 

[viperjeff]

Seen 82 on my speedo today and it got there really fast