Apollo DB-36 Bogging
 

Ive had the Apollo db-36 250 for about 6 months now and since the weather has changed from cold to warm, it boggs and jumps at anything past 1/4 throttle. Ive tried changing the carb to a nibbi, changing the jets, changing the needle position and repositioning the air screw. Nothing has had really any effect on it. Is there anything other than the carb that could be causing this?

Might check valve lash... that's the 1st thing that we'll tell you.

But you might check for a crack or leak in the intake manifold.

Easy things first. Spark plug. Non ethanol gas. Valve lash.

I hadn't thought of the spark plug, they are of dubious quality from China. Good call.