A question from Sweden

[Ybbe]

I wonder if someone increased the capacity from 350 to 500 and drilled the piston rather than rebalancing the crankshaft?

Is it possible to determine that without splitting the crankcase?

[clive]

Well a starting point would be the engine number. The piston looks to be for a 500. If the crankcases have an engine number starting 16 or G3 its pretty likely crank is a 350 one. Even if you split the cases its not easy to tell the difference. Years ago putting a 500 barrel on a 350 motor was pretty usual. Mostly what it causes is for the vibration range to move . Normally on a 350 its good to 50mph then can get vibrating and smooths out again just below 60. The bigger barrel is likely to make this vibration start at lower speeds but it may well smooth out again. Some 350s do not have a headsteady it is vital on a 500.
Good luck