Crankshaft Runout Question

[Northracing]

An update, I managed to true a crank before disassembling it and got it to a good spec - took many hours.

I disassembled the crank and no surprises, but unfortunately some light scoring on the timing side pin bore - the crank had been rebuilt in the past, the pin was clearly aftermarket. Good interference fit with new pin and bores according to my measurements.

Still have some cleaning to do, as well as clean out the sludge trap.

Question, how best to dress the scoring on the timing side pin bore?

Thank you.
Derek

[LaceyDucati]

Derek,
The scoring is sadly not unusual. The cause is often sharp edges of oil holes etc. Generally you can take off any high spots with a fine oil stone. I generally use a round stone around 3/8 diameter. Ideally new or in good condition, done carefully, you will see the high spots as you go. With care you won't remove anything significant. I prefer to do this rather than use a hone as you can just work on the high spots. The scores are mostly insignificant in themselves, only superficial.

Nigel