Thanks for the tip...keep me posted I will keep you posted, thanks.Honestly, I am in the same boat. My 06 660 dropped an exhaust valve at 1324 miles and 176 hours. My piston and cylinder are fine, my head may need replacing. Since I am pulling the engine anyway, I will split the cases and do a entire rebuild kit. There are some on ebay (not Chinese crap) for about $900. Might as well look at the bottom end to avoid having an issue later.
Just to see what's out there, if you decide to rebuild and go BIG, I've read this is a great kit, although more than I will spend. Plus I want to keep using standard pump gas.
THE MOST COMPLETE RHINO 660 MOTOR REBUILD KIT ON THE PLANET!This Rhino or Grizzly 660 719cc big bore stroker rebuild kit has it all. If you want to rebuild your motor right, this is the complete kit to go with. It includes:102mm NEW cylinderHotrods 4mm stroker crank with rodHobpracingatv.com