Gx160

As old as this post is, I don't know if you've done anything yet, but I have a small amount of information on these engines. I have a Gx160 on my bike and with no mods beyond no governor, I am capable of 45mph; maybe able to do better with a different pulley I have a single speed belt drive. It goes from the engine to the rear wheel with a belt tensioner pedal. If you want, I could figure out what the ratio is to run it at that speed.

http://www.affordablegokarts.com/mm..._Code=A&Product_Code=AGKPJS&Category_Code=PCJ
Is a good way to go I believe a few members have gone this route including culvercityclassic.Search culvercityclassic for his builds.

Howdy LiveSteamfan. Welcome to the forum.

Big time Moto, some great work.

You don't need gears with this motor, from our experience a total reduction of about 12:1 on a street bike is a pretty good starting point. Several ways to get to that magic ratio. If you are thinking of building with a Honda GX, you better build a platform that can handle the power/torque as these motors are not toys.

A good build thread for the GX160:

http://motorbicycling.com/showthread.php?t=40482

Be safe. Build safe.