Good luck finding cyl/pist parts. I bought one of the last two cyl/pist. replacements from Sig several months ago. Wish now I had snapped up both.

I have 8 .25 norvells mostly AMEs (bearing) and a couple Big Migs (non Bearing). All are capable of good performance in spite of the inherent design weirdness and parts that tend to vibrate out like screw in crancase back plate and carburator screws. And the ever popular Idle stop screw burr fouling the carb barrel and locking it up, etc. etc. etc. Norvell owners need read no further.

I have successfully damaged 5 motors by trying to start one with a loose back plate that I didn't see untill it was pulled out for inspection. Too late the damage was done. Sig was kind enough to warranty replace it.

Then I had two more break the rod in flight while relatively new, again Sig warrantied.

Total; 3 replacements from distributor no charge, all was right with the world. Back to the combat circuit.

Later running in two more new AME .25s and broke the rod in both in flight. Reluctantly bought the only repair parts ( the whole cyl/pist assembly) for the first when all I needed was a new rod. Factory not supplying just rods for parts.

When second rod breaks, no more cyl/pist assemblies left, so still not repaired.

On advice from Sig and other die hards still trying to run Norvells, I am adding castor to the tune of at least 20% total oil content that is at least half castor per gallon. Depending on the fuel you start with that could be anywhere from 4 to 8 oz. (or more)per gal! Better to err on the safe side and be a little gooey, loose a little performance and still have an engine that 's not broken.

So far so good. but now the combat season is upon us, we'll see how the Norvells fare this year.