gearing with track change?

[JoBoo]

I have an 02 800 RMK mod.. Last year I put on a 156x15x2.5 camo extreme and 8 tooth 3 pitch drivers and after that I couldn't get it to hold rpms. It shoots up to 8100 and then falls off to like 7600.

My previous track was a 159x15x2 2.52 pitch with 9 tooth drivers.

I also noticed I have a lot of belt heat. Do I need to gear down more to compensate for the track? I thought the 8 tooth 3 pitch drivers would be enough gear down to compensate but maybe not.

The rest of my setup: 800 carls ported/carbs bored. I have a cmx belt drive 28 tooth top sprocket and 60 tooth bottom sprocket ( should be 2.14 gear ratio). I've tried various clutch setups with both button and team. The last one I tried was: primary: 62 gram weight, almond round primary spring. Team secondary with team blk/red spring and team 66/44-42 helix. I think its in the 66/42 position. I think I tried less weight too but didn't have any affect.

Should I gear down, try stiffer secondary spring, other...?

Any input is appreciated, I only make one or two trips out west these days so hate to spend too much time tuning.

 

[winter brew]

I would go shallower on the helix, more track needs stronger backshift signal.....I would go with a 58/38.46 or even a 54/38.46 w/red/black and 2 delrin washers. I think you will see alot of heat go away and get back your RPM.
And gearing down may help, but I would do the helix first, then gear down if necessary.

 

[2zeros]

Driver change.....

The change you made in drivers actually geared you up. The 9 tooth 2.52 is 22.68 inches of circumferance. While the 8 tooth 3.0 is 24.0. To give this a comparison, it is like you put taller tires on your truck. So, to get back to where you started you would need to gear down. If you compare the gearing in the newer sleds, they are alot lower than your 02 RMK came with stock. I like a lower gear for myself, I run 2.55:1 (18/46). I would reccomend 2.3-2.4 to anyone. I ride mostly offtrail if possible and am a little heavier than most ( 240lbs). The lower gearing has limited my top speed a bit. But, I can still go 70MPH, and that is fine for me. But, my clutches are way cooler and I don't ever blow belts. I also ride 3-6k feet, (Wa. Cascades) on a 900Kingcat that is mostly stock except a muffler and some reeds. I hope this helps, Good luck!-00's I was also thinking helix, but don't have any Polaris experience so I can't give good advise on that. -00's

 

[XC700116]

^^ Second that I would look towards a 2.4 ish ratio.

 

[JoBoo]

Thanks for the replies.

Looks like I will look into both - gearing down and getting different helix. Probably helix first.

Does anyone know how the 3 pitch 8 tooth drivers compare to the new polaris drivers on the 08/09 800 Rmk? Meaning how big are the new polaris drivers.
I see stock gearing on the new 800's is 20/41 and most people recommend lower (19/42) but that should still be about where I am with gearing if drivers are similar.

bigger drivers cause higher gearing makes sense now, I was thinking of it like it was same as changing bottom gear.

 

[2zeros]

Drivers....

Multiply the number of teeth x the pitch = the circumferance. ( 8x3.0=24, 9x2.52=22.68) easy right? Also check out SLP's website for some other helpful formula's. They have a speed calculator that really helps figure things out. If you have a jackshaft rpm sensor, the formula works way better. I have made my best adjustments for clutching by using the second RPM. You will instantly know if your adjustment has helped you or hurt you. The only thing that is not perfect about the speed calculation formula, they assume that engine RPM and Jackshaft RPM are 1:1. They never are, it takes alot of horspower or no traction to achieve this. I think the only sleds to go 1:1 are boosted of some kind. I remember a very well known guy in the snomobile circle back in the day said, "Gear your sled for how fast you want to go". That stuck with me and I have learned alot just tinkering with clutches and gears. My motor and sled is mostly stock. And I feel pretty good about how it runs. Sorry if I blab about this too much but this is an interesting topic for me! Think snow-00's

 

[Eli]

I went from a 162 Attack 20 to an Extreme 156 2.5 lug Camo and the Camo Extreme pulled the engine down and it needed more backshift. I went a little heavier on the secondary spring and the problem was fixed. You should gear pretty low with this track because it bites pretty hard and holds track speeds lower than a lot of other tracks. The lower the track speed the more your clutches are compensating and building heat.