Theory of Clutching for Big Tracks

[Goinboardin]

I'm trying to dial in my 2004 Polaris RMK 800 (SLP twins) with a 174x16x2.5 track.

It has 7 tooth 3.0" drivers. 19/43 gears.

Brand new primary from IndyDan. Currently have brand new Polaris Almond spring, 10-58 weights (balanced & good bushings).

Secondary is TSS98. Team black/purple spring (new). Helix is 60-38-.36 ER.

New Poo 080 belt.

It will pull RPM on the trail, 8100RPM. Not quite pulling that RPM in off trail or up hills, more like 7800.

I have run it like this with 64-40-.36 ER and it was not pulling RPM on trail or off trail. So it seemed to like less helix.

Should I try less helix yet? This thing pulls very hard on the trail when it will tach, I'd love to see that in the deep or up a hill!

I keep reading about the BB 800 needing helix angle, but thats with smaller track sleds. This thing is loaded. Revs correct with less load, not when under more load.

Engine is running well, VES valves clean w/ new bellows, light springs, crank fresh, etc. Timing may be a little retarded. Going to check tomorrow. Think this could be killing me?

I'd like to hear what some others have seem as far as clutching NA sleds with big tracks and low gears.

THANKS

 

[j-gnar]

I put lighter weights in and got higher rpms - downside is my clutch is getting very hot. That could be the poor quality dayco belt, im putting a gates Kevlar on today and we will see if that helps. Seems to me that you might need nitrous or a turbo.

 

[Goinboardin]

Everyone needs a turbo

I have some 14:1 domes, maybe I'll try them out this weekend with some AV gas. Heading home now, going to check timing.

As it stands now I can rip around, then put my hand on the clutch. Its hot, but not burn my skin hot. I can hold it there ~15 seconds.

 

[4Z]

58/38 helix red/black spring

 

[Goinboardin]

I was wrong about my helix angles. Had 64-40 when it wasn't hitting RPM, right now it has 60-38.

I checked my timing tonight. Read 27* at 3250. Put a dial indicator in the plug hole and checked the factory timing marks, 0.5* retarded. So I was at 26.5* base timing. I now have it set at a true 29* (TPS unplugged) and have my TPS showing 4.0V at wide open throttle with a 5.0V source, smooth increase from closed to full as well. Going out in the AM, I'm betting it runs correctly now. I'll report back tomorrow evening.

Thanks for the tips guys. I'm surprised I had the timing that far off...no wonder it was a dog in the "regular" key mode and ran somewhat OK in the premium mode.

 

[assault 700]

get a 140\340 spring

 

[Goinboardin]

Setup for 174" on 04' Polaris RMK 800

Yep with the correct timing it pulls RPM. Like a whole new sled! Clutches are hot, but I can put my hand on them for ~10 seconds maybe 15. Not expecting much better with that track. I do have a shock tower vent, 2cool vents on the sides, and extra vents in the hood.

10-58
Polaris Almond, one delrin under spring

38-60-.36ER 2 delrins under spring cup
Team Black/Purple

3.0" 7 tooth drivers
19/43 gears in the case

SLP race twins, SLP cheater head, premix, 320 mains, stock needles in 2nd E-clip w/ 0.020" shim
10,000-11,000' 30*F day