I recently added a new O.S. 55AX to my Ultrasport Plus, I mounted it inverted and added an onboard ignition system. I am using 15% nitro fuel with 18% oil and a O.S. 8 glow plug. I am trying to get the engine running properly but I'm running into many issues. First of all, the carburetor seems to flood often, when I do get the engine running, I advance the throttle and it quits once the ignition system turns off. I've adjusted the high-end needle valve to the lean side but it's still giving me a lot of issues, spitting out a lot of unburned fuel, etc. I was told to run a 3-line fuel tank, use 30% nitro, use an O.S. F plug and lean out the idle screw. I don't fully understand the 3 line fuel tank, running two clunks, one to the muffler, one to the carburetor and plug the vent line.

Any helpful suggestions would be greatly appreciated.

Bill

Get the engine set up properly upright, first. You need the high-speed and low-speed settings for upright operation...that's because they're easy to get set in that configuration. Then mount the engine inverted. Flooding is normal with inverted installations. You'll need to clamp-off the fuel line when you're not running, or make sure the fuel level's lower than the carb. Even so, at low throttle operation, the engine can be problematic. With a #8 plug and an onboard system, you should be OK. Idle and acceleration are what become problematic with inverted running.

If the engine's not well-broken-in before it's mounted inverted, you'll likely have problems. It should be well-broken-in before you use it in anything but upright or side-mounted.