'87 KDX200 runs but randomly dies

[llaughlin802]

I've got an '87 with a completely fresh motor that's bored and running a KDX220 rod about 3mm longer than stock. It starts right up first kick and runs great, idles great, but completely randomly shuts off while idling. Doesn't bog or act like fuel starvation, shuts off like I hit the killswitch (which is currently bypassed). Wondering if anyone has ideas on where to start? I cleaned the carb thoroughly, my float and jets are correct, it never dies when I'm on the throttle, and it's getting plenty of fuel to the carb. It will start right up after dying, but never idles more than a minute without dying. I've got a small crack in the carb boot which I intend to fix but I figure that would cause rev-up, not stalling. Thanks guys!!

[bufftester]

Sounds like an ignition issue. Have you checked the coil, and the stator/pickups?

[Molly's 70]

What's the spark plug look like?

[KDXGarage]

How does that work with the longer rod?

Does it idle well if you blip the throttle some?

Maybe it is loading up if you are not clearing it out.

[llaughlin802]

Sounds like an ignition issue. Have you checked the coil, and the stator/pickups?

It's a full brand new aftermarket ignition.

[llaughlin802]

What's the spark plug look like?

Brand new. Even swapped it out on the off chance and regapped it. NGK plug

[llaughlin802]

How does that work with the longer rod?

Does it idle well if you blip the throttle some?

Maybe it is loading up if you are not clearing it out.

My crazy machinist and I made up an aluminum plate to block the jug up and had the motor ported to account for the new rod. He's pretty convinced it will lend me a whole bunch of power but I've never heard of someone doing this on the KDX and possible effects of the KIPS now. It will run for a while if I give it some revs every 10 seconds or so, I can keep it running at mid-higher RPM for a long time. I would imagine it would sound like it's bogging down if it was getting clogged up but maybe not? thanks for the reply

[KDXGarage]

Does it still have the power valve system?

I can't say that I ever focused on getting my bike to idle for a long time. They aren't taxi cabs. :-)

[llaughlin802]

Does it still have the power valve system?

I can't say that I ever focused on getting my bike to idle for a long time. They aren't taxi cabs. :-)

Yes it does still have the power valve system which appears to be working as I can see the rod move when I rev it up