Pee Wee needle chasing

wha-tah-hey Tue Aug 29, 2017 10:34 am

I replaced the needle spring with fuel tubing and installed a rebuild kit on one of my Pee Wees 'cause it wouldn't hold a setting.
Now I can peak it and in a few seconds hafta open OR close the needle, at times a full turn or more, to try holding peak.
It's a constant chase just to run out a tank.
Ideas of what's going on?

crankbndr Tue Aug 29, 2017 10:37 am

Air leaks, I had same issues with the tank screws and backplate tank seal.

wha-tah-hey Tue Aug 29, 2017 10:55 am

Thanks, crank - I'll check that.

Surfer_kris Tue Aug 29, 2017 12:23 pm

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.

wha-tah-hey Tue Aug 29, 2017 12:34 pm

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

wha-tah-hey Tue Aug 29, 2017 3:00 pm

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

roddie Tue Aug 29, 2017 7:09 pm

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.