A while back, I put on an HPD trail pipe and machined head from RCR. He also sent me and HPD clutch kit model # ATVCK4P which is for stock engine with HPD pipe. I am now in the process of a rebuild with a Wiseco .020 over and a trail port job on the cylinder from Bubba. Do I need to change my clutching? I see HPD has a model # ATVCK4M for stock or trail mod engines with HPD pipe. If I do have to change it, do I have to buy a complete kit again or can I just swap out some parts? Anyone know the difference between the 2 kits? I forget what color springs and what size weights my kit came with. I'm not so much concerned with getting top end speed. I'm after a trail machine that will put the front end skyward whenever I choose.

 

you need the atvck4ma clutch kit for trail porting,i think it is the gold
primary with 58 g of weights with violet secondary spring,helix should be 40/36 or 42/36,with the trail pipe this setup work best...

 

I had a HPD plain spring in my trail modded bike and it was good but it was bogging down on me in the sand on take off. Now I have the HPD red/yellow and love it!!!!!!!!!!! It stalls a little but not too bad. Now it takes off like a rocket. I couldn't believe what a difference a spring change could make. I would say save your money on the complete kit and just try the spring (which ever you decide on) and then make a decision on the whole kit.

 

duneaholic is right,HPD suggest the red/yellow primary with 58 of weights,for trail mod pipe only,it is another good issue if you're not intended to spend the money on the whole clutchs setup.