Originally Posted by
Pete S-RCU
needle valve is new, glo plug is OS-F.
Have run it in the plane, on the bench.
Tank holds pressure a long time, an hour at least.
Problem is when going up in a steep climb.
Also will falter if I try to richen the mixture on the ground.
After all the cleaning I did, seems better, will have to fly it to be sure.
Needle valve is very sensitive. have to adjust it very slowly.
If the fuel feed line inside the tank has a split near the metal tubing....when the fuel level uncovers the split such as nose up or level with a half tank or less....
It will go lean and quit.
Also....under G-force, fuel line anywhere can flop around and open a split causing a loss of pressure....and go lean...then close up again.
I have had to use Du-Bro fuel line since Prather went out of business and that DB fuel line is so soft and full of debris that I have had a lot of trouble.
The DB line has chalk or powder inside and small silicone chips too. The chips are just about invisible if they get inside the n/v area.
I started flushing all the lines before installation but it is still prone to splitting....I hate that stuff.
Also....weird problems can be caused by a worn out piston ring causing some blow-by which upsets the crankcase pressure which in turn affects the mixture.
Is your engine a 140 Sport or the earlier model?
Does it have the 4 holes or slots on the outside circumference of the piston??
The earlier 140 did not have these holes and was a local mod done by YS Performance.
The 140 Sport came from the factory with 4 slots. The compression of the piston went through these holes and pressed the ring against the cylinder.
This caused much better ring sealing and much of the weird problems went away.
You should check to see which piston you have...you can remove the plug to look into the head to see the top of the piston.