Originally Posted by Intrepid Wheelwoman
There's no need to heat to a high temperature. If you're careful just heating the cylinder up slowly in an ordinary domestic oven will be fine (Oh it's so wonderful being the lady of the house). It's trying to bend the fins on a cold alloy casting that will mostly result in failure.
Ease the fins gently, use smooth jaw pliers and it's useful to have them hot too. Oven mitts are the kitchen bench engine mechanic's best friend.
How many bent China girl cylinder fins have you straightened?
I have straightened fins with smooth jawed wide needle nose pliers
on well over 500 motors
and continue to straighten a few on my
new motors which don't seem to have too many bent.
NEVER ever broken one
They are thin and pliable and usually bend back really easily and
I never use heat.
If a get a tough one near the intake or exhaust or some webbing I
leave it bent.
I have noticed that a few old bushing motors had much thicker fins
and cleaner castings and there was some machining done on them in
various places that aren't done today.
The heads on the other hand are die cast and the fins if bent can not
be straightened and they will break off instead of bend most of the time.