Ok I have read every reply and here is my 2 pennies. I'm going to write this assuming zero knowledge. I realize this ain't your first rodeo but if someone just starting out is reading they may benefit from some extra details.
Overlap: Your fine. You only have 35 degrees of overlap. My Peewee and Demon have almost twice that at 60 degrees. The thing about overlap is, the lower the RPM the less vacuum created. That means fuel can't be pulled through the carb at very low rpm. What that means is I can't start the Peewee by hand like Bob Shutt can. I use an RC starter and just pop the trigger and it's running. It's not "harder to start" it just requires a higher starter speed. Ron Colonna had the same problem with his Novi V8 for years. Drill motor just didn't spin fast enough. He put a pull string on it and gave it a pull and it fired.
Another thing about overlap is once started the engine has less resistance from closed valves and will idle at a lower rpm than the same engine with no overlap. My V8 has an almost realistic idle. Hard to do in an engine that small. I just realized I'm giving away all my secrets! I guess that's what forums are for.
Also check your ignition timing. If your not waste firing check what cycle your firing on. Bring the engine to TDC and mark the crank position. Rotate the crank until both valves are open. Then rotate another 360 degrees to TDC again. This is where you should fire. My engines final setting was over 30 degrees advance. Don't be afraid to start out at 15 or 20 degrees advance and work from there. We don't have vacuum or mechanical advance so put some in there. I use a timing light to check mine.
So I guess verify, verify, verify everything which it sounds like you have and try spinning the engine faster. If your getting little pops your right there. Try spinning the motor with your starter and close the carb needle all the way and then slowly open it until you get some pops. Then work from there.
