Easing up in the weather allowed me to get a Primary Force going. The FP40 that ran a consistent fat two stroke on a Twister was less hospitable on the PF. Running half a tank than going lean overpowering the plane. Engine was set up in Philly Flyer mode. Extra head gasket, 10.5x4.5 apc, Powermaster 5%, 22%, .283 venturi, OS needlevalve, Enya #3 plug, free flowing tongue muffler. These were initial runs of engine in a new plane. I'm running a non-uniflo tank on muffler pressure. Many options to improve the run. First off, richen needle. Since non-uniflo tanks lean out during flight, it is possible that starting richer would have put the engine into a happy and useful mode. Uniflo tank may have reduced the effect of head change keeping the initial needle setting throughout flight. I put in another head gasket. Problem solved. Much wider adjustment in needle. It was easy to tune in a rich setting that leaned out gradually during flight, providing more power for the later shapes.

Observations: 1. moving engine from one plane to another can require a new round of tuning. (Different vibration characteristics, difference in load on engine etc.) 2. An extra head gasket (making for three total in this engine) softens the power characteristic, reining in runaway.

I'm satisfied with the way the engine runs. Fat 2 stroke that leans gradually, never over lean, no runaway. Same power upright and inverted. I'll probably try a uniflo tank on muffler pressure and atmospheric pressure. RSM has taken over the GRW tank line. Good metal tanks. Will try a uniflo version of the standard vent GRW tank I'm using now.