I replaced two pistons on my Yamaha 800 XLT. When putting back together I notice that one of the YPVS cover bolts will not tighten down good and air leaks from this. The YPVS is attached to the cylinder so I assume this cannot be good. The ski fires up and runs fine out of water but in water stalls and rough idles. I also noticed the piston head cover on this piston get alot hotter than the other piston cover. Do you think this is causing my problems or should I look elsewhere?