Hitchcocks Forum

I have just rebuilt my 500 bullet engine and in the struggle to fit the timing shaft through the inner bearing race, I fear it may have been knocked the crankshaft out of alignment. Can anyone help with symptoms of this. The engine turns ok but runs unevenly on idling. I have been looking at the various other causes of this but have had no success yet. I really don't want to dismantle the engine again unless I have to!

Hi Trumpetman. Have a decco at my thread regarding my 350 Bullet crankshaft alignment for information. I think you would really struggle to put a crankshaft out of alignment whilst trying to fit it into a bearing - unless you were using a 6lb lump hammer! If it was out of alignment, it would not turn when the crankcase was fully tightned. When you say it runs unevenly, do you mean lumpy with considerable vibration or just not as smooth as it should? Dave

Thanks Dave that's reassuring. The engine is very lumpy with quite a lot of vibration but maybe I haven't got it timed up accurately. The timing marks on the cams are a bit vague so could possibly be a tooth out? I didn't use a 6ld hammer but must confess to loosing my patience and hitting it quite hard with a rubber mallet! Cheers Paul

Simply bumping a built up crank on a bench can be enough to put it out of alignment...


If you have replaced the main bearings due to wear, then the crank shaft will have flexed and the fit of the crank pin in the flywheels should have been checked; most will have fretted the fly wheel eyes to a taper.

Undo all the bolts to the crankcases and lay down the engine on its side. Fix the lower half so it does not move and spin the shaft. If the upper half case gently held moves with a bigger circle and does not stay in the correct place it is because the shaft has moved.