Model Forum / Radio Controlled / Air Models / November 2006

Any possibility that the pressure nipple on the muffler is clogged?

Cheers -- \_________Lyman Slack________/
                \_______Flying Gators R/C___/
                   \_____AMA 6430 LM____ /
                      \___Gainesville FL_____/
Visit my Web Site at www.LymanSlack.com

I run my 52 unpressurised, and that primes ok on full throttle, but I always
use a starter to turn it over.
The engine is ringed so if the ring has stuck/broken this would cause no
compression or suction on the down stroke.

Paul

Have an unusal problem that has just surfaced with my near new OS 52 4
Stroke....
Never had a problem priming it until recently it would not prime at all.

I have always primed by having the throttle wide open than placing my finger
over
the exhaust. Then I turn the prop through a couple of strokes and the fuel
sucks up
through the fuel line and into the carby. Works every time and starts first
flip.

Now, it won't prime at all unless I flip the prop really fast over and over
heaps of
times even then it sometimes won't prime unless I use an electric starter...

I have tried swapping fuel tanks and fuel tubing to no avail. I have checked
the carby for leaks and also the backplate. No leaks found. I have
readjusted the
valves and checked for leaks around the exhaust. No leaks found. The engine
has plenty of compression but it just won't suck the fuel up. Even when I
finally get
it to start it idles fine but full throttle running is very wierd. It goes
rich,lean,rich,lean,
rich,lean every second or so. It definitely sounds like an air leak
somewhere but its
got me stumped where it could be???

Could a sticky or bent valve cause this problem?? There just doesnt seem to
be
enough exhaust pressure getting to the fuel tank and enough suction from the
cylinder.
Yet the compression feels fine.

Appreciate any help here guys.

Cheers,

Troy.