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Category: Pre War
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Date: 17 Jun 2003
Time: 23:02:05


Can anybody help with this 2 cyl.pre war engine problem. I have had the crank,flywheel,pistons and rods etc balanced. It was necessary to add 70 grams weight to each throw. The crank just went into the back of the crankcase with the extra weights.

The pots were relined back to std with new pistons. The liners are held in with small screws thru' the pot wall and then machined off inside and out. No sign of any movement with these screw plugs. The liners were machined out at the bottom to clear the con rod.

THE PROBLEM IS:- It starts and sounds fine. Drive it 50 metres and a VERY loud knock starts. You stop to investigate and the noise just dies away gradually. Start up, another 50 metres or so and it repeats itself time and again.

Its been suggested the crank has broken. Can it be noisey sometimes and then ok? Oil pressure is fine at 30psi. Running in with 20W 50 oil.

Any other suggestions would be helpfulbefore I strip the engine. Does anybody know if adding 70 grams to the balance weights could cause the problem and possible breakage?

Last changed: November 19, 2008