crankshaft roundness

[AFGuy]

Anyone know what the roundness spec is for the crankshaft's connecting rod journal? It's not in the GS500 manual. I thought it was runout, but that is completely different. Need help so I don't have to buy a new crankshaft or engine!

[burning1]

Any out of round state should appear as runout, so I'm not sure what else you'd need...

[adidasguy]

I will be parting out Junior's old motor bottom end. That's the one with the bad counter balance bearing. Rest of the innerds is good. Case is obviously toast because of the counter balancer running on the case and banging it inside. Let me know if you want it. About 30,000 km on that motor.

[burning1]

BTW: The manual does have thickness specs for all the journals. You could measure the journal from a couple of directions to make sure the diameter is consistent and within spec. Runout is mainly to make sure the crank is straight. Need a dial indicator and a couple of V blocks for that.

[slipperymongoose]

I would imagine it would be no more than +/-0.05mm Maybe more maybe less.

[AFGuy]

I actually figured it out through the thickness specs, so you guys were right. It has a tolerance of .0009 inches, which is waaaay tighter than what my crank is when using a reference measurement. With that and other parts bad, time for this guy to buy a new engine

[burning1]

Did you lose a bearing? Same position - it's possible to repair a crank journal, but it isn't really cost effective vs getting a new crank on ebay. I'd only consider it if you had a re-balanced crank.