Thanks for the replies, as always everyone here is always willing to help.

I installed a OS.91 two cycle. It was installed in accordance to the instructions, and I'm having a problem with the carb filling up with fuel(gravity feeding) so I can't get the engine to run.

It looks like the tank is to high...and I can't figure a way to move it without a lot of sugury on the airframe, and there isn't much room to work in there.
That's why I was looking to install the G23.

Can someone give an idea on how to solve this. A couple of guys at the field suggested I should install a Cline regulator.

I pretty sure someone has installed the OS 91 FX and I was hoping they could shed some light on how they did it.

I'm willing to try an OS 120 four cycle if I can install it without moving the stock location of the fuel tank.

I believe that if you use the four stroke you need a special manifold to allow the muffler to fit in the channel under the nose.
Can someone give that Part Number.

Thanks for all your help.

P. S. I love Bipes also.....just finished a Sig Hog Bipe