From: rbs@sawtooth.idaho.amdahl.com (Bob Smith)
Newsgroups: rec.models.rc
Subject: Re: K&B Help Wanted! (Was Re: Radio Selection)
Date: 17 Nov 92 21:55:49 GMT
Distribution: usa
Organization: Amdahl Corp., Rexburg, ID

In article <Uf2Fp2K00iUyQ2dlcG@andrew.cmu.edu>, mm7q+@andrew.cmu.edu (Michael Oliver Muller) writes:
> Hello-
> 
> (stuff about K&B vs. O.S., stuff about details of engine problems deleted)My 
> 
> >question is: How do I set this engine so that it both idles and
> >                transitions to full throttle without quitting?
> 
> I have a Royal 40, and I have the exact same problem. Any suggestions on
> fixing this problem would be GREATLY appreciated. (Short of buying the
> seemingly superior O.S. engines :) )
> Mike Muller

Ok, I've successfully set up a new Royal .45 recently, so here's how I did it.
First, even an ABC engine needs to be run a little to loosen up, but not
nearly as much as a ringed engine.  Also, it needs to be run a little 
leaner (but still rich) so the piston and sleeve get hot enough to have
a correct fit.  Assuming you've done that, adjust the needle valve at
wide open throttle so you're a few hundred RPM on the rich side of peak.
Close the throttle to idle.  You'll probably have to set the idle stop screw
(on the back side of the carb sticking up) so the barrel doesn't close
too much.  Open the throttle slowly and watch how the engine reacts.  If it
sputters, surges, or fuel drops spray out of the carb, it's too rich.  Close the
low-speed mixture screw slightly (about 1/8 to 1/16 of a turn).  If it dies
immediately and you don't see any fuel, it's too lean.  Open the mixture
screw.  Re-start the engine and repeat ad-infinitum!

One problem I had with the engine is that if the mixture is way off, it's hard
to tell if it's too lean or too rich.  (Actually, it's not always easy to tell
when it's close to the correct setting either!)  In that case, just close it
way down 'til you're pretty sure it's to lean, then slowly open it 1/8 turn
at a time until the engine will transition decently.  Once it transitions,
re-set the high speed needle; then check the low speed again.  You might
need to iterate a couple times between the two until both are set right.

I've gone through the above procedure (spending about half an hour) and then
not had to bother with the settings at all through a summer of flying.  Most
of the twiddling I do after that is because I can't resist messing with the
high-speed needle to make sure it's running at best speed, not because I
really need to!

Setting up engines to run well is somewhat of an art that has to be practiced.
I'm still learning, but I have had several successes getting somewhat cranky
engines to run (yes, even an OS!).  It takes some trial and error.  That's
why I always try to set up an engine at home on a test stand so I'm not
out at the field fuming over a poorly running engine when I want to be
flying!  Plus you're not tempted to take off with a poorly running engine
and then practice your dead stick landings.

If all else fails, go to the field and find somebody who can help you.  There's
almost always somebody who'll take it as a challenge to get your engine running!

Good luck!

Bob Smith