The tank does not require a lot of pressure, you only need about 1-2psi from the exhaust to provide adecuate pressure for the fuel.

Somehow I doubt that you got a nipple that is not the right size. If anything since you re-drilled it is likely you installed a slightly larger one.

But the nipples can fill with crud that gets blown in by the engine very quickly... even if the nipple or engine is new.

All the more so if you've been screwing around with the engine, as you may dislodge junk that has built up inside.

Check by hooking a piece of clean tubing to the nipple and blow through the clean end. (Remember though that pressure is building up inside the muffler and you may be blowing in the wrong direction so to speak, which is why I still advocate checking to make sure the opening is free of debris. )


Do the same for the carb.

You can use the same technique ( I use a small brass tube hooked to clean tubing ) for the fuel tank too.

You should be able to pressurize the tank by blowing, but the pressure will not diminish over time which indicates a leak.


Super Tigers are a bit problematic at times during transitions...

Some engines I've had are very smooth.

Others can be set to EITHER transition well but idle poorly ( too rich, they bog down ) or idle great but transition bad.

When I get one of these problematic engines ( fortunately so far I've only had two ) I use this fix...



My Gallery has the article associated with that image...

It cured my problematic SuperTigre, but I'm not sure this is what you need.