ORIGINAL: Nosedragger
Fuel drop out is caused by the air fuel mixture slowing down while traveling in the intake.The inside radius of the intake could cause that.
If the performance now is that same as with the stock carb, its probably not a problem.
So it looks like my inlet manifold is ok then.
ORIGINAL: Nosedragger
The only time the stock muffler is a restriction to be concerend with, is if the spark arrestor screen is clogged. We have gutted them and all it does is make it louder.
I have removed the spark arrestor already so just eh exit pipe now, I now believe this to be flowing ok as it runs no better without the exhaust.
ORIGINAL: Nosedragger
Don't waste your time looking for a buttefly smaller than 12.5mm, if you do find one the venturi will be too small.
9.5 -10mm is about right for a GX31, any larger is a waste because the engine can't use it and the vacuum signal in the venturi gets weaker as you go larger.
The venturi can be drilled out and re profiled to suit, I have done it with good affect in the past but perhaps not suitable for the GX31.
ORIGINAL: Nosedragger
If you try a straight pipe on the exhaust make the inside match the opening at the exhaust port face and leave the pipe long, paint it with cheap spray on paint, run the engine (without prop) until it burns the paint off the pipe close to the engine, where the paint stops burning off is the shortest you want to cut it.
I will make another exhaust alter to fit inside the cowl of the SE5a but I don't think I can better the standard flow and sound. I ran it up on a nasty paint stirring Master classic 20" X 8" which weighs a ton! Whilst it only revved to 5000rpm and took a little longer to get there than with my home brew wooden 18x8 the thrust was right up and would pull my B&D workmate over so perhaps that's what I will settle for as a forum member said:
"
According to Reivers', that gives about 12 lbs of thrust and 1.5 hp. (Master Airstirrer prop used as basis for calculation)"
which I would have thought plenty to pull around a 80" SE5a?