21/38 gearing on extended Apex

[Maurizio Benelli]

I bet there´s couple of topics on this matter, but I can´t find any.

So, I´m thinking of 21/38 gearing on my Apex ER (extended to 144"). Will I need a clutch kit/new settings in clutch? Will it over rev or something?

 

[Super Sled]

That seems really low gearing for a 144", unless your going through really deep powder and maintaing track speed is an issue. What is wrong with your current gearing set up?

And more than likely if you gear down like that with no clutching changes you're clutching will be off. And I agree it will be too high rpm's. You use stock weights in your clutch now? Prob want to get adjustable weights to tune them and bring the rpm's down. Or else you could try different Yamaha weights for the Mt sleds.

 

[sherlock29]

My RTX is 22/38 and 40th 24/38.... very noticable gearing defference... especailly in fuel... if your gonna do the off trail all the time it would be fun.. but i'm in the 40% off tail 60% on... and i'm leaving my gearing the same... havn't tried the 144 with stock gearing, but i do so much river running that i dont want to loose the "cruising" speeds...

 

[Maurizio Benelli]

My current gearing is 23/38 and the problem is that I sort of run out of power in the deep snow. I got stuck couple of times last winter when the track just didn't roll anymore. So would you suggest going 22/38 instead of 21/38? I don't need 100mph+ speeds and I drive 90% off trails.

 

[pro116]

What size drivers do you have on?Tha makes a big diffrence.

 

[Maurizio Benelli]

I have 8T wahl bros extros.

 

[Super Sled]

I have 8T wahl bros extros.

With those drivers, your already geared down a bit from 9T stock drivers, so I wouldnt think you have to gear down very much more to hit the sweet spot. 22/38 perhaps?

 

[Maurizio Benelli]

My sled is originally an ER, so it came with 9T drivers and 24/38 gearing. I might try 22/38 for now. What do you think, do I need changes in clutch setup?

 

[Super Sled]

That's what I'd do -- start out going down 1 more to 22/38 first. I bet that provide a lot more track speed through powder for you.

And about the clutching, try it out. You'll know if your over revving. If you do ever hit the rev limiter, you'll need to add more weight to your clutch arms to bring the rpm's down.

 

[Sled Dog]

Try out this gearing to speed calculator.

http://www.totallyamaha.com/snowmobiles ... tches.html

 

[Maurizio Benelli]

About the clutching..

What spring would you recommend for my off trail use? I´d like it to be "softer", I can´t describe in better words what I mean. English is not my native language.

 

[Sled Dog]

About the clutching..

What spring would you recommend for my off trail use? I´d like it to be "softer", I can´t describe in better words what I mean. English is not my native language.

By softer do you mean the way the primary engages and takes off?

 

[Maurizio Benelli]

About the clutching..

What spring would you recommend for my off trail use? I´d like it to be "softer", I can´t describe in better words what I mean. English is not my native language.

By softer do you mean the way the primary engages and takes off?

Yes, exactly what I mean. Now when it engages, it usually digs down in the snow.

 

[Sled Dog]

Ok now that we know what your looking for we can help you out. So you are looking for a smooth engagement and top end really does not matter. If thats correct what is the rpm where your primary engages now.

 

[grader]

that gearing is very low, with a calculated top speed of only 92mph. if you want it even lower i suggest a larger bottom sprocket such as a 40 tooth. smaller sprockets are less efecient. i have been running an rx-136 with 10 tooth drivers and 22-42 gears for years with good results, and this year will stretch it to 144 and will switch bottom to a 43 tooth gear. this will still give me a top speed of 109. down from 112 last year. as for a better primary spring try an orange-silver-orange from yamaha, it is 5kg less on engagement than stock, but has a high shift rate and final shift out to build rpm. stock weights will work but might have to be adjusted with rivets to maintain top rpm.