1987 XC 250 losing spark

Hi all,
I recently got a 1987 XC 250. When I bought the bike the guy said that it had no spark, but when I got it home, took out the plug and cranked it over it had a big spark. So I cleaned the carb, changed the oil and it started right up and ran great. The next day when I went and tried to start the bike it just would not kick start, I thought it was flooded so I tried bump starting it and it started up again. The next day I tried to start it again and it would not start, so I decided to pull the plug and it had no spark. But when I put the plug back in it again and tried to bump start it, it started up again. It seems that Once the bike starts it runs flawlessly with no problems at all, and as soon as it starts and I shut it off it starts first kick. This problem seems to happen whenever I let the bike sit overnight or for a few days. I checked the wires all over the bike and none of them seem to be frayed or bare in any part. the flywheel and stator also look clean. I know that it is not a problem with the kill switch because it does not actually have one, just a wire coming from the cdi that you ground to the frame when you want to shut it off. Does anybody have an idea what could be causing this problem?

pull the ignition cover and see if you have a Motoplat or SEM

One of the things I read in the 86 service manual for no spark said to make sure your grounds are clean. The ignition coil bolts right to the frame under tank, and that is your ground.

look your stop erngine in the handlbar !

get a kill switch on it!
check your plug cap..it likely needs a new one, or at least unscrew it from the wire. then trim a small amount from the lead, then screw cap back on. i always convert a husky to a good hard plastic ngk unit with brass internals. lots of issues from plug caps!

The kill switch is sticking in the off position sometimes. Let it hang off the handle bar and try it.

Second check the kill switch wire for a bare spot.

This has tested me a few times

I run a ground wire in the loom between the ignition bolt and the coil bolt to be safe and certain

his post says he has no kill switch. just a dangling wire. he also states he has looked all over his wires and cannot see any bare spots.

you can never have too many grounds..i run an extra ground on the trucks i build at work for many things..the led lights that are installed on everything like to get a very faint "feedback" when the ground isnt strong.

It has and SEM Ignition

the SEM is a crap shoot
they run fine then leave you walking
seems the magnets can come loose and pretty much mess up the works
but the bigger issue is the internal grounding failure
best bet find a Motoplat or go aftermarket

i think a motoplat must be run with a plat coil..splicing wont help

I THINK I HAVE 4 REBUILD ABLE PLATES INCLUDING THE ONE OFF MY 87 250 WR