[SKELLEY521]

I plan on updating my Primary Sheave this fall so I was searching for spring options for tuning.

I am not sure on the specs of our Secondary Clutch Spring or the Finish Rate, but I'm posting what I find for tuning options.
Looks like EPI has 2 options:
https://epiperformance.com/secondary-6/
.

 

[SKELLEY521]

It also appears EPI has Package Clutch Kits.
https://epiperformance.com/wolverine-4/

 

[SKELLEY521]

I'm really liking my High Velocity Roller Weights, so link for others.
https://www.hunterworks.com/inc/sdetail/123661/34145

 

[Paul65]

I had not heard of them, thanks for sharing. Their "kit" appears to be the secondary spring & roller weights. Since we already have weights... I will look forward to what you come up with on the secondary spring tuning.

Ref: SPORT UTILITY CLUTCH KIT - 27-28" TIRES - WE437617

And they sell a secondary spring compressor: CLUTCH COMPRESSION TOOL - CCT510

 

[Cam53]

I haven't heard of them either and would really like to hear from anyone with 1st hand experience with these springs. Glad you brought this up. I'm also looking to upgrade to the HW sheaves in the spring so I'd really like to hear from those that have tried this spring with that setup.

 

[therebel19]

EPI is big in the Polaris World. I had one of their kits in my Ranger. It was good. For Yamaha, stick to JBS or Hunterworks and what they recommend. More than likely secondary isn't needed in the X platform but listen your sheave grinder.

 

[SKELLEY521]

Basics with what we have to tune.

-Stiffer Secondary Spring Finish Rate = Slower Upshift, Faster Backshift
-Softer Secondary Spring Finish Rate = Faster Upshift, Slower Backshift

-More Primary Clutch Weight = Less RPM & greater belt squeezing force
-Less Primary Clutch Weight = More RPM & less belt squeezing force

Roller weights basically set the belt squeeze force as it relates to RPM's to overcome the Secondary Spring rate. (Shift Phase)
You will also notice a difference in engine braking depending on your tune.

I'm after performance, so I want the shift phase to happen close to the motors powerband w/o being to annoying.
It's a fine line as you can cause some ill effects such as a jerky throttle or engine braking to soon.

I probably won't do any testing until later this Fall/Winter depending on work schedule.
Just thought I would post some info for others and if anyone does any tuning, let us know what you think.
I need to find the rates of our stock spring also.

 

[SKELLEY521]

Right, right, but I'm going to tune a stock sheave to my liking first, then when I upgrade, I'll be able to really notice the smalls and see if it was worth it.
And yes, I'm going to shim out the stock primary too for more bottom.

EPI is big in the Polaris World. I had one of their kits in my Ranger. It was good. For Yamaha, stick to JBS or Hunterworks and what they recommend. More than likely secondary isn't needed in the X platform but listen your sheave grinder.

 

[Paul65]

Blaze that trail, bud. We are behind you 100% and appreciate what you do.

 

[19Wherry]

Good work Skelly. As an update on the secondary spring cup. Babbitts emailed me that the updated version has shipped. So Yamaha must be getting stock back in.