The kit I bought and put in my Predator came with 18lb valve springs. I put them in the same time I installed a billet flywheel and rod. However, my engine doesnt seem to rev any faster, and in fact sounds like it misses a few cycles at WOT. Stock springs are supposed to be 10.8lbs. How should I measure to be sure what I put in was 18 lbs? Or do you think I am just running out of cam? What cam would be a good replacement? This is for a yard kart btw.