I have a predator 90 that has the 28mm carb and pipe and porting by hetrick. I drilled out the shoes and am using red springs. I want to get the engagement a little higher. Do they make stiffer springs than the red? Anything else I can do?

 

Reduce the roller weight and/or drill the shoes more.

 

Get an ultralight rear clutch it'll engage as high as you want it to. They are about $75 to $150 I got one from Billy at WRH Racing for about $100 and one here locally at a shop for $75 billys is maybe a little better made. They pull nice and hard off the line but not good for trails due to heat.

 

Fastest... Can you explain the heat build up on the aftermarket one? It just doesn't take heat well??? Or creates more heat?

 

Lighter weights spin more on the hub, thus more heat.