i have a 02 blaster when i start it up it makes a banging noise and keeps doing it while its running i checked compression it reads 125 which i belive is ok everything on the quad is stock my thought is its the rod or crank bearings i cant tell if it is coming from the cylinder or the crankcase ifit is the rod or crank bearings should i get it rebored or should i just replace the worn bearings oh it has not lost any power and the kickstart feels the same

 

maybe you should get one of those cool engine stephescopes or what ever their called. mayve those would work

 

sounds low i hear alot of piston slap might bea wearing poss rebiuld??? my 2 cents

 

mine did the same tthing before the rebuild blown rod bearing

 

the bearing on the crank or the top of the rod near the piston

 

on the rod near the piston..

 

125 is OK. Here's another thing to check. Make sure the pipe is completely sealing to the cylinder. If not, use Permatex exhaust sealant. After rebuilding my Blaster, I had a slight leak, and let me tell you it does sound like engine knock

 

ok i just ripped it apart there are vertical streaks on the front (exhaust side) of the piston as well as on the back side (carb side) the back streaks are a little deeper and the one ring was stuck in the groove i think from rubbing there is no up and down play on the connecting rod and there is no play on the flywheel so ithink the crank bearings are ok what else can it be

 

OH BABY, I got lots of experience with that!! Rebuild time buddy. You probably ran too lean, burnt the piston into the ring. Sounds like you need a bore job too. Total of $150-$200. Need a gasket kit, ring, piston with pin clips, and the boring. Make sure you get a shop that bores it to spec, the next oversize that cleans up the wall gouges. If they screw up the boring, you won't get enough compression.

After the re-build, you need to fix why it burned up, or you'll be doing it all over again

 

that happiend to me to running to lean will mes everything up except when i took my motor apart it was all black and burnt up. buy and oil block off kit and run premix the ratio i run is 40:1 just standard injector oil