Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Thanks again, I think the valves don't seal up properly as I can see fuel spray out of carb intake.  How can I take out the valves on this engine ? I managed to file the valve rockets to sit even which helped.

Compression seems quite good on that cylinder. And spark from coil seems strong.

Whats strange is the black stuff from the right exhaust, I would have expected unburnt fuel to be more clear. It almost seems like oil contamination in the cylinder even though I didn't add any oil to crank case.  Probably need to take it apart and check the piston ring .