Reply To: cr125 bottom end

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Doug Welch


Moto engines for all SKUSA classes the rod and flywheels are stock, OEM, no modifications. Some builders take the stock asembly, directly from Honda as it is assembled and put it in the engine. Some builders use a press to slightly widen the flywheels to give a bit more side clearance to the rod and then polish flywheel bearing surfaces ( the shafts that go into the crank bearings) for a slip fit in the bearings. They do not touch the rod bearing surfaces for giving them more clearance will result in things you don’t want. 😥

In your case, I would buy a crank kit from Honda (they come pre-assembled) and cost less than $120 from several different sources. I would install it with no modifications and go have fun. It’s cheap, reliable, and the power difference between a crank that is blueprinted like I suggest and a stock one is impreceptable to a driver of S2 abilities. Don’t waste your money. Spend the $$ you save on track time. The track time will pay off in the long run far more than any blueprinting you do to the crank.