hello
im just wondering if my muffler can produce too much backpressure. It was running a little rich with the HS needle at 1/2 turn and the low speed was at about a 1/3 of a turn out. I was surprised i had no clue the engine would run with the needles so far in. Could this be because of the muffler pressure. I run a moosecan pipe and i bought a large ID pressure nipple becuase the previous muffler didn't supply enough. The engine is a Webra 50. Is there anything wrong with running it like that. it seems fine but the low speed needle controls everything up to 4/5 throttle so its kinda hard to set right.
thanks

Tom

Your low speed is set too rich. Lean it out, and reset the main needle.
You will get an over-all better run, and transition.

FBD.

A lot of the larger Magnum engines run with the HS needle at 1/2 turn.

Enjoy,

Jim

the low end needle is at 1/3 of a turn. I cannot really lean it out anymore.

Tom

I have a Rossi .45 that is "just cracked" at 1/8 turn. It is still a tad
rich, but I like it that way....to cool down after running full blast.

Most times I have to leave the glow heat on till the motor warms up
a bit, and I open it up and let it run full speed for about 20 seconds to
"blow it out' before I remove the glow. When the engine gets to full
operating temp, it's just right.

Close the low speed, and open it 1/8 turn, with the carb barrel just cracked
open. Set the high speed, with only a 200 drop for richness. Now check
the low speed, and see how it transitions. Make any final adjustments
to the low speed, and see where you are now. I'll bet it's much better.

FBD.

ok i'll try that tommorow, i think i might also try restricting the pressure nipple a little bit to see what that does. When I lift the nose up there is no noticible difference in rpm and it doesn't matter on how rich the engine is.

Tom

Pull the pressure line off the muffler completely and see what an effect it has.
Also try setting the high speed at dead flat peak....full blast....not richened for
flight when setting the low end.

Dave.

ok
i ran and flew it today and it was perfect after i leaned everthing out. thanks for the suggestions. I did restrict pressure a little bit and it didn't seem to do much but i dont care anymore. Another thing is that a wood prop will run like crap and APC runs perfect. maybe the weight has to do something but it doesn't matter becuase the APC is way superior in the air. thanks again

Tom