'93 KDX 200 fail to start with engine warmed up.

[Rather be Riding]

Hello all,

I've been prowling on the forum for some time without making any posts. I've finally found the time to work on my KDX and have fixed her up a bunch compared to how she was. Details follow:

-Cyclepedia and this forum have been my references
-93 KDX 200, hours unknown (odometer removed)
-New ProX top end (less than 3 hours)
-KIPS cleaned and functioning properly (at least everything actuates smoothly)
-130 psi compression (cylinder walls have decent wear/damage. Planning on sending to Millennium Technologies in another season)
-BR8ES plug installed
-FMF Gold series pipe (old, a little dented, pretty dirty inside)
-Stock silencer (it's loud, I suspect the spark arrestor/internal has been removed. The thing is rusted shut. I'd have to saw it open)
-Stock reed box with new Boyesen carbon reed
-Stock Keihin PWK 38 carb with 150 main and 48 pilot jets. Needle set at stock 4th position from the bottom.

Riding at 4800' - 5000' MSL

It starts up quick and runs well the first time I get on her. After I've ran her for a while and kill the motor, she won't start up again. I have to wait awhile before she'll start. I pulled the plug and it looked black, oily, rich. I leaned the needle position out to the 4th position. This is the stock position. The bike is still giving me the same problem and the plug is still looking slightly rich, although better.

I plan on taking it through the jetting guide to dial it in, but first wanted to make sure I have a good baseline. I replaced the reeds and took the carb apart to find that it seems I'm missing an o ring/seal from under the choke/enrichener. Cyclepedia shows a small seal in there under the plunger but I've got nothing. The plunger is fine though. Can't even find this little seal on the OEM parts finders from Cyclepedia or Rocky Mountain. Could this be causing my delayed rich condition?

I cleaned the jets, though they seemed mostly fine. I'll have to verify the float height somehow, and then I'm going to install all this back together. Once that's done, I'll run through the jetting guide. Hopefully that fixes the issue for me. Anyone have any other ideas as to what might be causing this?

[KDXGarage]

PWK35 or 38??

Check the electronics.

Look on sudco or jetsrus for the carb diagram.

[bufftester]

+1 on checking electronics. Doesn't sound like a fuel delivery issue. Check all your connections and especially your grounds. Then make sure your coil and stator meet specs. Would be very interesting to check them at the start of a ride and immediately when it quits running.

[Rather be Riding]

PWK35 or 38??

Check the electronics.

Look on sudco or jetsrus for the carb diagram.

Going off of Cyclepedia, it should be a 35. All the Jets are sized as Cyclepedia says it should be. All I saw stamped on the carb is "PWK".


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[Rather be Riding]

+1 on checking electronics. Doesn't sound like a fuel delivery issue. Check all your connections and especially your grounds. Then make sure your coil and stator meet specs. Would be very interesting to check them at the start of a ride and immediately when it quits running.

I hooked up a spark tester on it, and attempted to start it while hot. It lit up like it's supposed to, so I know I'm getting spark. I'll look for some troubleshooting procedures on here and give that a shot.


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