I have an aftermarket cdi on a 10590 M-Series, It runs ok for the most part. I do have an annoying ping that comes and goes. I originally thought that it was from a dirty idle and main jet. I have cleaned both numerous times, installed a in line filter and siliconed the air filter gasket as it was not sealing letting in air. My plug is black, no part is brown. To me its running very rich. I think the pinging I am getting is the plug taken a partial foul. I installed a new plug and mowed the lawn. After I was done running in the garage I started to get the same pinging signs again. Pulled the plug and its black as the ace of spades. I really do not believe the jetting is that rich I think its in the voltage coming from the cdi. Does anyone have a recommendation for a cdi supplier or should I try and find one used off another M-series. Thanks,