Helix Question

[sleslie]

I have a 2009 Nytro with a 190 MCX kit with the following clutch setup:

Primary - blue/white/blue
14.5 rollers
MCX 77.8gr weights
18/40 gearing
Arctic Cat purple secondary wound to 0-1
39* helix
162" track
I'm a big guy, probably close to 300lbs geared up.
Ride all the popular places in B.C at approx. 6-8000'.

My question is if would benefit me at all to try a steeper angled helix, or even an adjustable shockwave. Belt life seems pretty good right now. Right now it revs out at about 9000rpm, would a steeper angle drop my rpms too much? I see most guys run a 47* or adjustable, my sled runs good but i'm always looking for a bit more. Thanks for any advice.

 

[robb]

I run a 47 deg helex with 8bu full load Yamaha pins in them. Also polish the ramps on the helex. Don't use the shockwave they make the clutch bind. Then you start slipping belts.

 

[sleslie]

I guess my question is if there is a benefit of switching helix angle's, why do you run a 47* instead of a 39*?

 

[sledfvr]

47 helix will backshift quicker and make the sled feel more responsive.

 

[sleslie]

Thanks sledfvr, i think i'll give it a try, Any idea how much rpm i'll lose switching from the 39 to 47?

 

[SNAFU]

I think your spring is too stiff for that combination and it is not allowing full shift out. Did you ever try the stock secondary spring (white I think)? That is what I use on my 190 and I hit 8700-8800 rpm. I am still playing with clutching but it seems close enough. Primary is same as yours expect weights are 8BU's loaded. Can't remember the total weight.

I think a 47 deg helix is too much for a 190 kit. 45 deg would be the max. I also tried a shock wave running at 43 deg with AC green spring and it was okay for RPM (8600). However, the ramps are narrow and wore groves in the bottons. I put my stock helix back on and used a Yamaha white spring with stock pre-load winding.

I'll sell you the shock wave if you want to try it.

 

[TBird]

47 helix will backshift quicker and make the sled feel more responsive.

Opposite of this!
Just had to clarify that an steeper helix have worse backshift then an with lower angle, this means, an helix with an 39° helix have better backhift then with an 47° helix, and feels more responsive, an excellent corner to corner helix if there's no problem with hitting the rpm limiter.
An steeper helix shifts up faster = better acceleration, loads the engine more, but have less belt grip (belt slippage) and not as good backshift.
Clutching can be done in a million diffrent ways, a good thumb of rule is not to change to much, less prone to stumble in to problems, the holy grale is to find the right balance between primary and secondary.
I would not go as far as an 47°, not more then 43° from your description of how your sled works, i would also finetune your primary with an diffrent spring.

 

[sleslie]

I did try the white secondary spring, i think i wound it 1-6 instead of 3-3 and i was pretty happy with it. Seems like i'm getting better belt life and lower temps with the A/C purple spring though. I don't think the A/C purple is the same as the EPI purple that most people run with the bigger boost kits. I might just leave well enough alone and run this for now, in some real soft powder it might drop rpm's down to the sweet spot, i am a bit high right now. I thnk i will stay away from the Shockwave.

 

[Mcx Nytro]

Opposite of this!
Just had to clarify that an steeper helix have worse backshift then an with lower angle, this means, an helix with an 39° helix have better backhift then with an 47° helix, and feels more responsive, an excellent corner to corner helix if there's no problem with hitting the rpm limiter.
An steeper helix shifts up faster = better acceleration, loads the engine more, but have less belt grip (belt slippage) and not as good backshift.
Clutching can be done in a million diffrent ways, a good thumb of rule is not to change to much, less prone to stumble in to problems, the holy grale is to find the right balance between primary and secondary.
I would not go as far as an 47°, not more then 43° from your description of how your sled works, i would also finetune your primary with an diffrent spring.

He is correct But one thing to remember is turbos don't like too much helix I ran a 56/50 on my BB Viper the turbo wkould not pull that even with more hp One more thing is change only ONE thing at a time so you know what is working or not working

 

[sleslie]

Thanks TBird, i was thinking about maybe trying a small step and going to a 41 instead of the 39, might just try that and see what happens, or leave it alone still, defiitely undecided right now.

 

[TBird]

He is correct But one thing to remember is turbos don't like too much helix I ran a 56/50 on my BB Viper the turbo wkould not pull that even with more hp One more thing is change only ONE thing at a time so you know what is working or not working

Everything is possible, i have run 54/48 on an Apex MTX MCX, worked decent, but in my opinion you are correct, i am running much more shallow helix now a days, but without trying no learning .
With an shallower helix response are much better.

Using Tapatalk on Android ICS pad.