One thing to check: does the choke plate seat fully? Some people have found that it doesn’t for a couple of reasons. One is that the plate will simply not close due to the plate not being assembled properly from Walbro. The other is that the choke servo is not setup properly so that it does not seat.
It could also be an electrical problem but there is an easy way to see if you are not drawing fuel. Take the cowlng off if necessary and get full view of the fuel supply line to the carb. When you first prime the engine does the fuel climb up the line nice and fast like it's supposed to? Mine goes like an inch or two each flip. It gets up to the carb very fast. If yours does not it's either a choke problem or the pump in the carb is not working right. Is the pressure pulse line sealed? No leaks? Make sure it's getting healthy pressure pulses form the crank case. Are there any air leaks in the fuel supply line or tank fittings?
ORIGINAL: zope_pope
I understand factory settings aren't what I should run it on, but I have tuned the engine so that it runs the top end rpm and backed it off a few hundred. I have also leaned the low end till it tries to die when the throttle is advanced and then richened it off, but it just doesn't want to fire within (literally) the first 50 flips. I'd love to cover the carb with a finger and prime, but the engine is very much in a cowl. Also, I cant get it to fire even while choking. I read an article in Model Aviation yesterday that recommends filling the whole in the choke plate. Good idea, bad idea? I think it would make a lot better seal and easier to prime the engine. Thanks so far for the advice, I'll pull the engine afterwork and do some inspecting and post the results.