No Spark @ Low RPMS

I'm not getting a spark @ low RPMs....Meaning I have to peddle my ass off to start the bike. (66cc China) Once started, runs great until clutch is pulled and rpms fall, bike stalls. Running HD lightning. Changed HD cdi coil, magneto, switched to stock cdi, 3 new plugs BH6. ported motor. 41 tooth sprocket. Check for spark by removing plug, running with bike. Even tied up rear wheel off ground and peddled.....Only gets spark when outta breath and arm falls off. What do ya think?

cleaned off the ground path contacts on the new stator coil (which I assume you call a magneto)?
adjusted float bowl height?
lowered needle? tried with and without air filter?
planed down the irregular surfaced head so that you have enough compression to start?

New stater sanded, Del clone carb, k&n style air filter, clean, Fred Head 6.0. resurfaced jug top. Tested the spark. only getting spark at higher rpms. higher rpms as in getting spark just before hitting top peddle speed. Not a fuel issue.....

it's true that the stator coil outputs more voltage as the rpm raises.
you won't be the first person to buy a new stator coil and find that its just as bad as the one you took off.
order a magneto while you're at it in case its magnetic field strength is weak. (maybe it was dropped)

it just hit me that you have a high compression head. they require more gap voltage to allow a spark. check the compression and if its more than 135 then add another head gasket or use a rotary tool to wallow out the inner dome of the head.

Thanks. Gonna get a Screaming Roo stater coil (magneto) and new magnet as well. This was all happening before head was added....

Oh.....The simple things....Changed out my plug wire...Fires right up!