crank assembly balancing after new rod?

about to tear my bike down again. the suzuki shop rebuilt my engine 30 hours ago with a new rod and bearings. when i got it running it vibrated badly. now i have a blown gear and i am tearing it down again. i think they did a bad job of balancing the while i am there what can i do without any special balancing tool?? and how does a shop do this the right way?

I have never had to re balance a crank when replaceing the rod and bearings. Piston weight is usually the problem.

When you get the crank assy. out check it for runout. You will need a dial indicator to measure that, and a way to hold and turn the crank. I usually use two dead centers in the lathe, but I have a set of V blocks that are necessary at times. Any machine shop can check it for you. It's best to pull the main bearings and check the shafts next to to the flywheel. Anything over .0005" needs to be trued.

ive done a few RM250 cranks and they all had around .0015 runout from the factory. using a lead hammer, v blocks and dial indicators you can get them to where the dial indicator wont read any runout.

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