Pee Wee needle chasing

Thanks, crank - I'll check that.

Check the tiny o-ring by the venturi.
If there is a leak there it will get fuel when the tank is full and air when the tank is running low...

A too large prop and over-heating can also cause similar problems/symptoms.

Good call, Chris - I forgot about the o-ring!
I'm running a 4.5x2 Cox so not over-heating.

OK, new o-ring, not the fastest but it's stable now.
Thanks, fellows!

I'd gotten away from running tanked engines and opted for the product backplates/external tanks on my .049's. You might want to watch eBay for Cox "Sky-Copter" engines complete with mount. CEF member "batjack" (Mark) has done some experimenting with this. The engine is a .020 from the case forward.. but has a plastic backplate/carb and NVA that can be modified for use with the tank of your choice.



He used a "Pee Wee" back-plate as a template to produce a nifty low-profile radial-mount having a "Pee Wee" mounts' footprint.




Notice the case-screw "heads" protruding from the backside. This actually allows some clearance for air-flow to the back of the carb when mounted to a firewall. A small piece of filter-material placed between the back-plate and firewall would be a good addition, to help keep the intake-air clean.




Just something to think about.. seeing that you have three engines to play with.