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 16:38:11 GMT
Distribution: usa
Organization: Amdahl Corp., Rexburg, ID

In article <1992Nov17.064137.32454@kronos.com>, ed@kronos.com (Ed Baker) writes:
> I've seen the K&B threads before, but I had never encountered an actual
> K&B engine until last week at the flying field.  A new student (1st time)
> showed up with a nice Royal 40-T ARF trainer plane w/ KB 40.  I/We told him
> that we wouldinstruct himm.
> 
> I spent most of the day having him start the engine, and taxi the plane to
> the far end of the runway.  I would slowly increase the throttle, and the
> engine would die.
> 
> I could not get his engine to run right; it would die on the runway every
> time.  I finally adapted to the engine characteristics, and we had a great
> 1st flight!  I had to overcome my insistence that the engine both idle and
> run at full speed, with a transition between the two.  A couple of times I
> let the engine idle for over a minute, and then pushed the trottle up one
> clock only to have it die.  I took that plane out to the far end of the
> runway at least 5 times, only to have the engine die there.  Very amusing
> to my co-fliers :-).
> 
> The engine was very consistent; it died every time.  So, to keep it going,
> one had to keep it at very high idle.  It flew just fine, then!
> 
> My question is: How do I set this engine so that it both idles and
>                 transitions to full throttle without quitting?
> 
> >(Now the Sportsters, that's a different matter!).
> 
> Maybe this engine is one of these.
> 

I believe the Sportster is a .46.  My only problem with Sportsters is that
they're essentially a throw away engine - once it's worn out there's not
much you can do to rebuild them.  Some people really like them - cheap, reasonable
performance, etc.  

As far as your problems with the K&B .40, it probably hasn't been broken in.
I've had problems similar to what you describe, and I've found you shouldn't
even think about setting the low-speed idle or getting any kind of transition
unless you've gone through at least half an hour of running with a break-in
procedure. (ie, running very rich, then leaning out momentarily, then rich again,
etc.)  An hour's even better.  The K&B is a ringed engine and needs this running
to seat the rings.  (BTW, Fox engines are notorious for needing long break-in
periods.  But once properly broken in, they're not too bad.)  Also, the low speed 
mixture adjustment (small screw opposite the needle valve) is very sensitive.
Don't adjust it more than 1/8 or 1/16 of a turn at a time - it's easy to go right
past the correct setting.

I admit, the K&B is not as forgiving in set up as an OS or other more expensive
engines, but that's one of the things you sacrifice for the $50 savings.  I've
had times I wanted to huck the thing in the garbage, but with a little patience
it's been a fine running engine.  (had it for almost 10 years now.)

Well, I'm not an engine expert, but I play one on TV :-).  I'd run it on the
ground for a while to make sure it's loosened up, then go through the process
of setting the idle and high-speed mixtures to get decent idle and transition.

Bob