timing problem CDI?

hey all i got a 99 ktm 200mxc two stroke that just had a stator failure, so i replaced it today when i got my new electrosport stator. she started right up almost first kick but has bad pinging and didnt want to run, so i went back in and retarded the timing a little. this helped but the ping was still there and still bad, so i retarded more and more until i ran out of adjustment, it almost runs right fully retarded but as i increase the rpms it pings hard i can hear it/feel it its obvious. it also is kicking back at me as i kickstart. it feels like its detonating before tdc. so i checked the resistance of the coil and pick up both were fine so was the ac discharge at the spark plug boot. my real question is if this is actually the cdi malfunctioning? at full retard the bike seems to idle ok but with rpm increase it starts knocking like the cdi is not retarding timing with rpm any suggestions or thoughts?

are you sure your moving the pickup coil the right direction? is the key sheared on the flywheel?

no keyway is fine and yes im moving the pickup with the direction of engine rotation, making spark occur later. i tried giving it some advance but after a couple degrees it couldnt start at all, good points though

is it wired right? sparking off the lighting coil instead of the ignition???? are you getting multiple sparks at the plug when you spin it over? It's also possible the the new staror is postioned wrong? correct part #? mounting screw holes in the same place as the stocker?

ya its wired right headlight output not hooked up its the right part number has good resistance, same mount holes and correct spark per rotation

You need to align the "fire marks", there is a mark on the flywheel/rotor and one on the stator. Roll it CCW from the ignition side (direction it runs) and with the piston 1.1mm or around .043" of an inch BTDC. You may have to get a Motion Pro dial indicator, its what I use, but if you have a 0-6" dial caliper, can be done, little trickier, but doable.

When you have the piston at 1.1mm BTDC, rotate the stator mark to alight with the mark on the flywheel. Then recheck to make sure its right after tightening it all down.

there are no marks on the rotor only one on the stator backplate and one on the engine case where the backplate mounts to i have these lined up already i can post a pic if u dont believe me

I think it's unlikely, but I have had problems on a KX where a bad CDI box wasn't advancing timing. Easy to check with a $10 timing light hooked to a battery. See if it advances/retards when you rev it. I don't know where it's supposed to be, or how much it should move, but I'm pretty sure it should move.

Maybe bad stator caused bad CDI or vice-versa?

thanks for the input bill it does seem unlikely but ive tried everything several different jetting sets air screw adjustment its not lean, i just ordered the cdi box though seems to be common with bad "kick back". this makes sense because i guess the cdi unit retards timing even at idle rpms! ill update this when i get the new one in like two weeks

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now