So That Was What It Was!

My setup is exactly the same and works perfectly.Can’t understand what the problem might be but I’d give it another go because the GP silencer is REALLY NOISY.

Jon, here is part of a topic on Flying Giants is verifies my thoughts - www.flyinggiants.com/forums/showthread.php?t=287709&page=5

and www.flyinggiants.com/forums/showpost.php?p=3116127&postcount=73

At present there appears to be no good answer to the muffler issues with GP engines, at least in the USA and Canada.

Update: Well here is my final view and answer on this subject. On Thursday 8th I did a quick noise test with the help of Simon with the GP original "muffler" fitted. Taken at ground level at a distance of 7 metres at WOT = RPM 7650. Prop Falcon 20x8 Front 94db, Sides 90 db, From Behind 86 db. The "bark" from the exhaust at any thing above half throttle is not nice. So, I have decided that at the moment the Extra is NOT flyable. If the OS exhaust is fitted I lose 1000rpm and max out at 6600. An option is to try a 22x10 prop but that might be just too much load, moving in to the 50cc domain here I think. I don't know which way to go for now.

Tuned pipe :woohoo:

You said you got the OS exhaust from BMFA, was it new or second hand??

If it was second hand there is a possibility that it is clogged up

Phil - General opinion from the pits area confirms your test results.
PLANE TOO NOISY.
Regards
Colin.