surging in flight
2 clubmembers & me built 3 of the RCGuys Treehoppers. It is my first gasser. We have 3 identical conversion 26cc engines. All 3 engines were brand new. 2 of us converted to EIC & one remains magneto. We all changed from the stock carb to a Walbro WT. Mine has a problem.
In flight it surges or pulses & seems rich. On the ground it runs perfect. Last nite we stayed till dark working on mine. We put in a rebuild kit, tuned carb. Sounds great. good idle, transition, and hi rpm. Once I take off it sounds good as it's climbing out, once I bank around & level off it starts the surging at full throttle. I can reduce to mid throttle & it seems OK. We made minor adjustments the carb multiple times last evening. I've read about the vent hole, & pressures etc. I do NOT have a cowl, can this still be a problem. If so why do my friends engines not do the same.
My carb is a Walbro WT-45A. one guys is a WT-645, not sure of the others.
I noticed at home last eve that my throttle linkage (ball link) is very sloppy. I wonder if under a no-load situation (such as level flight, the plane is a floater) the butterfy might be moving around. on the ground it is always under full load with the plane fixed as it is also under a full load on takeoff.
I'm planning on soldering a tube to the vent hole & running a hose into the fuse thru the firewall to see.
Driving me crazy...almost there anyhow.
Ken