Gearing 20/42 to 19/43

[14RMK144]

So I've never tuned my sleds, always rode older, just to be able to ride. (all I could afford, no extra money for mods lucky to keep em running). Till last few years.
So my 600 RMK has 20/42 gearing. If I go to 19/43, will that give me a little ski lift when I pin it? And a better hole shot? Or will it be a trencher off trail?
I see these 800's wheelie like no tomorrow these must be turbos? Or at least big bore kits? Don't quite have that money this year, hope to do big bore next summer.
O.M. says also 72 pitch, whats that? Thinking its the angle of the gear teeth, need a chain to match?
If I change gears will I need a new chain or when you buy new gears? Or do they have options of pitch so you can use same chain. Sled only has 1200 miles so chain is still good.
Thinking this would be the least expensive, and easiest for me to do myself.
Whats my other options? Clutching? What changes would I do to the clutches. Is it do it yourself job. Or need shop to do it. I've changed weights but that's the extent of any clutch work I've done. Handy and mechanically inclined, but not a mechanic. I've done top ends, cleaned carbs and changed jets, track swaps, changed out suspension then set camber and alignment, all maintenance and stuff like that.
Any advice or pointed to resources is highly appreciated. Thanks in advance.

 

[14RMK144]

TTT, Sure could use some help (info) hate to just start throwing parts at it without any idea if what I'm doing is sound idea.
Tried some google search, (not exactly my "cup of tea") Don't seem to get relevant results. Same for doing a search within Snowest.

 

[pulltype_polaris]

You can go to 19/43 with the same chain. The pitch of the chain refers to length or number of rollers. Cant remember exactly. Anyhow i did this swap with my 800 assault.you lose some top speed and get a little more hole shot but its not that huge of a jump. Belt runs cooler in the deep stuff. Not a waste of money. I think some guys were going as low as 19/46 with a different chain.

 

[Cinno]

Lower gearing will give you more torque in the 2500 - 8000 rpm region before the clutches start to shift. Once the clutches start to shift, the change in CVT ratio negates the lower chain case ratio.

The higher chain case ratio will require you to lower the primary clutch weights. If that is too coarse of an adjustment then a higher rate primary spring would work.

Another option to changing gearing it to call Carls Cycle and inquire if they have a clutch kit for your sled. They are very good at optimizing clutching.

Cinno

 

[Scott]

Chain pitch is the number of teeth (or links) in the chain.

Lower gearing doesn't necessarily make it wheelie easier. Too many factors involved in that just to say yes or now.
But lower gearing does give it more snap and the clutches do run cooler.

Cinno, lower gearing DOES effect top end speed. You lose mph on the top end when you gear down. It definitely changes the MPH of the full RPM range. The CVT transmission/clutches do not overcome lower gearing.

 

[Cinno]

Chain pitch is the number of teeth (or links) in the chain.

Lower gearing doesn't necessarily make it wheelie easier. Too many factors involved in that just to say yes or now.
But lower gearing does give it more snap and the clutches do run cooler.

Cinno, lower gearing DOES effect top end speed. You lose mph on the top end when you gear down. It definitely changes the MPH of the full RPM range. The CVT transmission/clutches do not overcome lower gearing.

The CVT DOES overcome lower gearing by shifting earlier right up until it hits the max shift point (min gear ratio). At that point I agree the gear down will limit the speed but who cares. He wanted to lift the ski's and get a better holeshot, which will happen with lower gearing right up until the CTV starts to shift (~15-20mph) after that the addition torque provided by the lower gearing is negated by the change in CTV ratio. So sled acceleration from there on will be about the same as stock gearing. I also recommended a clutch kit, because a good one will give you better acceleration/backshift over the entire range of operation without limiting top speed.

Cinno

 

[14RMK144]

The CVT DOES overcome lower gearing by shifting earlier right up until it hits the max shift point (min gear ratio). At that point I agree the gear down will limit the speed but who cares. He wanted to lift the ski's and get a better holeshot, which will happen with lower gearing right up until the CTV starts to shift (~15-20mph) after that the addition torque provided by the lower gearing is negated by the change in CTV ratio. So sled acceleration from there on will be about the same as stock gearing. I also recommended a clutch kit, because a good one will give you better acceleration/backshift over the entire range of operation without limiting top speed.

Cinno

Your near me, I'm in Oakdale. Any where local for clutching. Guys have reccomemd Carl's cycle but would rather get local. For instance if I do big bore going to go with Bikeman performance.

 

[Cinno]

Your near me, I'm in Oakdale. Any where local for clutching. Guys have reccomemd Carl's cycle but would rather get local. For instance if I do big bore going to go with Bikeman performance.

Most of my snowmobile vacation time is dedicated to mountain riding with friends. Several of the more experienced riders started using Carls Cycle clutch kits over 15 years ago and never looked back. They do specialize in mountain clutch kits. Local performance shops around here generally specialize in trail sled performance. I have heard good things about Bikeman as one friend has a snowcross race team and he has a good relationship with Bikeman.

Cinno

 

[Iowa_assault]

I have the same sled a 2014 rmk 144 600. I dropped the top tooth from 20t down to 19t. I left the bottom at stock which is 42. Its a night and say different and the sled is so much more torquey and responsive. you do lose some top speed though.

 

[14RMK144]

I have the same sled a 2014 rmk 144 600. I dropped the top tooth from 20t down to 19t. I left the bottom at stock which is 42. Its a night and say different and the sled is so much more torquey and responsive. you do lose some top speed though.

THANKS, not worried about top speed. With only changing 1 gear, can you use stock chain is there enough adjustment in tensioner?

 

[Iowa_assault]

Plenty

 

[Scott]

The CVT DOES overcome lower gearing by shifting earlier right up until it hits the max shift point (min gear ratio). At that point I agree the gear down will limit the speed but who cares. He wanted to lift the ski's and get a better holeshot, which will happen with lower gearing right up until the CTV starts to shift (~15-20mph) after that the addition torque provided by the lower gearing is negated by the change in CTV ratio. So sled acceleration from there on will be about the same as stock gearing. I also recommended a clutch kit, because a good one will give you better acceleration/backshift over the entire range of operation without limiting top speed.

Cinno

OK I understand what you are saying.

I was looking at it a different way.
Gearing down does reduce your top end speed.

 

[norpaq]

Really old thread I know, but I have older machines.

Would lowering the gear ratio make it friendlier on low speed tight trails? Looking to set-up a machine for my wife.

 

[Scott]

Yes.

 

[Al_Bell]

Hey dose anyone know what size of chain you need on 2018 pro rmk assault when gearing to a 19/43? The stock chain coming off a 20/40 dose not work.

 

[TRS]

 

[Al_Bell]

View attachment 361019

Thanks that’s a huge help!