In article m,
Jim Stewart wrote:

I'm rebuilding the top end of a 1964 Honda
S90 motorcycle engine. The work is nearly
done, but I'm concerned about the 40 years
of accumulated gunk in the crankcase. I
really *don't* want to split the case, but
I would like to flush it out somehow.

I'm thinking that before I put the cylinder
and head back on, I could fill the case with
stoddard solvent, kick it over a few times,
drain it and repeat. Before starting the
engine, I'll fill it with fresh oil, which
I'll replace after 15 minutes or so of running.

Would this be a good idea or will I mess
something up?

One trick I know of for cleaning smaller engines is to drain the oil
and refill it with diesel oil instead. Then run the engine for five to
fifteen minutes, drain, add the regular oil. Any diesel left behind
will diffuse into the oil and not cause any trouble. Works great as PM
on power equipment, but I don't think it'll clean up 40 years of crap in
a motorcycle engine without screwing something up.
Probably best to split the case.

--
B.B. --I am not a goat! thegoat4 at airmail.net
Fire the stupid--Vote.