how far back to you have the spark?

the hot rod setup has the spark plug quite close to the end of the exhaust on the ones I have seen.

I cant believe that o2 is the only problem here. I doubt that these engines really burn THAT clean. Never done anything like this so I cant really say for sure.

Long pipe with a plug near the end, running rich, at or near full throttle would be the way I would try it. Also open the gap very wide on that exhaust plug. I would only try pumping flammables into the exhaust as a last resort (and maybe not even then). If you use a flammable liquid do not use exhaust pressure to pump it, only used a pump designed for that fluid. Do not pump any fluid at low throttle.

Good luck. If you get it working take some pics and post em for us.

Rob


Of course, this is all theoretical and for discussion purposes only and never to be tried in real life. The comments above are not the opinions of RCU or Ryobi or even me. Who said that? I dont know what you are talking about. I'm outta here!