Adjustable Timing Magnet
As some of you may have discovered, not all of these engines perform the same.
Bogging, 2-stroking, and a lack of overall power, can be traced back to ignition timing that is incorrect. You can have your carburetor mixture adjusted perfectly, install a tuned pipe, and/or high compression cylinder head; and still have very poor performance due to incorrect ignition timing.
From the factory these engines are typically set-up with the timing 2-5 degrees advanced...which is about 15 degrees retarded from ideal.
The PK-80 engines that Pirate Cycles had last year were noticeably more powerful than all of the others we tested...the ignition timing was 12 degrees advanced on these engines. The engines were night and day; more torquey than any of the others.
Interestingly enough the Chinese do understand that 20 degrees advanced is a good starting point...The crankshaft key slot is cut at 20 degrees from T.D.C...Unfortunately the magnet guy ran his broach through at, (you guessed it), approximately 20 degrees...which completely nullifies the 20 degrees of advance that the crank maker built in. It’s like they couldn’t agree who was going to create the off-set key…so they both did. Do it twice just to be sure!
There isn't enough room inside the case to allow for any sort of backing plate that would allow for rotating the coil...an adjustable magnet is the only way to easily alter the timing.
Slightly advancing the ignition timing makes a HUGE difference in the performance.
Obviously you don't want to go too far advanced...too much isn't good either.
A retarded ignition causes bogging, misfiring, (four stroking), poor fuel economy, and fouled plugs.
Too far advanced and you risk overheating, detonation, and piston seizure.