blasters are easy to work on!!!!!like twelve bolts hold the case together...no gaskets between cases.just good ol yamabond!entire gasket kit includeing all new oil seals.50$ebay...025 over piston kit 105$ get weisco worth the few extra dollars.local mac. shop bore 30-50!make sure u ask them to chamfer the exhaust and intake ports, also send the new piston with it to the mac. shop so they can bore it exactly to the piston...the jug can vary due to wear and might need slight under bore

 

also make sure u examine the bottom end of the cases in the crank area.had the same problem on a blaster piston skirt in the bottom end,problem is there is no telling how many times the crank turned over and mashed the chunk into the cases...mine had like 4 or 5 hair line fractures,rebuilt only to lock up after about 3 rides due to sucking air through fractures.jet kit would be good too