Im looking for some advice on what to do next with my clutching. Machine is a 2010 550XP.

It all started with a harsh engagement that made it difficult to crawl over logs and rocks. I already have installed an EPI kit and didnt like it. I since have modified the EPI kit to get closer to what I want. The kit came with

50g weights
EPI Orange primary spring (PATV2) Rating 87/140
Bright green secondary spring (PEBS12) 120/225
EPI Helix

This set up from EPI had my engagement at 2900 RPM. The engagement was a little easier to control but it was just too high. At full throttle The bottom end and hit off the line was great but WOT was holding at 7050RPM. This was too high.. It just felt flat and after the initial hit of up to 20MPH it just felt like overrev. Im guessing mine was revving too high due to my mods. I have big gun exhaust, Twin air oval vent in the top of the airbox, High flow filter, and Big gun fuel controller. EPI said 6650 offered the fasted 300ft drag and thats where the sport utility kit was SUPPOSED to put it.

I put the stock 54g weights back in to bring the RPM back down but it took them too far and was setting at 6350 and engagement was down to about 2300. I ended up changing the primary spring to the EPI Silver spring (PATV13) Rating is 71/155. This gave me a just right engagement of 2100 and held WOT at 6500RPM.

Not a huge deal, but if I could Id like to get WOT up about 150RPM. Anybody have experience grinding stock weights to lighten them about 1.5-2g?

Also another question. Ive read that the secondary spring can greatly affect acceleration and that you should run the lightest secondary spring you can without the belt slipping. Is this true? Reason I ask is cause the bright green secondary spring that came in the kit is pretty dam stout. It was FAR more pressure than the spring I took out. I was able to press on the stock spring with my thumbs and have a friend undo the snap ring. Could not even get CLOSE doing that with the EPI spring.

I know what the weights and primary spring control but what exactly does the lighter or heavier secondary do and how does it affect the acceleration?

 

Well on the weights. yes you can grind them lighter. you will need a something to weigh them. like a triple beam balance scale. you can also solder lead onto them to make them heavier to.

A lighter secondary spring will make it upshift quicker. possibly making the max shiftout rpm lower. higher gear ratio. will not backshift very well

A heavier sec spring will keep the bike in a lower gear longer. helps backshift
max shiftout will be higher. will also grip the belt tighter.

backshift-
if you were to run at a hill wide open. like when snowmobiling. as the hill gets steaper the engine can't pull the gear ratio. if the clutches don't respond the rpm will fall off.
better backshift also helps the response, when on and off the throttle on the trail.

 

What weights are in it 10-54,20-54 or S54? I would find a set of weights that are a grm lighter.
the secondary spring senses the torque at the rear wheels and compensates for that on the clutch.Tighter gets more rpms and better backshift.Lighter will get more topend speed but slower back shift and less rpms.
I had to go up 4 grams from a 10RH 50g to a 10AL 54g to get my rpms down from 6750 to 6600.

 

They say 23-54.

 

Get on Ebay and try to find a cheap set of 10AL