200x starts great cold. But refuses to once warm

[SasquatchAtc]

Hey all,

So I've got an 84 200x with an 85 motor in it. I've adjusted the valves to the book specs.

However it still will start 1st or 2nd kick cold and idle/rip around great. But once she runs for 45 minutes to an hour, then it flat dies. It'll want to fire every 5-10 kicks but she won't stay running for more than 5 seconds.

Let it sit for about 10 minutes or more then it starts on the first couple kicks. Then does the same thing.

Anyone have any ideas to throw out here

[SasquatchAtc]

Should I increase the valve clearances a little bit?

[350for350]

If the valves are in spec, they should be fine. My first thought when I read this was that maybe you're running a little bit on the lean side with your jetting.

[SasquatchAtc]

Thanks man. I'll check out the jetting. Now that you mention it, it did seem to start to do this shortly after I rebuilt the carb

[ATC200X4716]

Couple things to consider...45 minutes is a pretty long time to be "fine" before something goes wrong.

First - is is sparking when it is dead?

Make sure you have good fuel flow to the carb from the tank. It could start out full and run great, and the tank cannot replenish the carb fast enough so over time the fuel level in the carb gets lower and lower until it can't run anymore, then it dies. Wait 10 minutes and the slow-to-replenish fuel supply fills the carb up and everything is good again, until it happens again. 45 mins is a long time to be good, I would expect like 5-10 mins maybe

You could have an electrical problem where a coil in the engine fails when it gets hot. It's rare but I've had it happen. Everything is fine cold and when the coils heat up there is a wear spot in a wire that opens up with heat and it stops sparking, and when it cools a bit everything is fine again. I would not expect it to go 45 minutes, but stat ohming out your coils if you haven't already, then then them after it dies and see if something goes out of range. Could be a CDI stopping working once it gets warm.

[robgdds]

"You could have an electrical problem where a coil in the engine fails when it gets hot. It's rare but I've had it happen. Everything is fine cold and when the coils heat up there is a wear spot in a wire that opens up with heat and it stops sparking, and when it cools a bit everything is fine again."
This is exactly what I fixed a few days ago, after it got hot turning left or tilting it to the right would make it turn off. It ended up being a wear spot on the ignition coil.

[ATC200X4716]

Nice! good to hear it's back on the trail....

[SasquatchAtc]

Thanks for all the replies. I'm gonna take it out on the trails next weekend. But it has passed the back yard test. I fiddled around with some jetting and cleaned all the electrical connections. She's running great now

[Dirtcrasher]

When the engine is hot, check the valve clearance, is there any play at TDC on the comp stroke??

Lots of the 1st gen 200X heads have excessive play with the cam to the head journals due to low oil or lousy oil, lets that clearance change quite a bit once hot.

Would be interesting to see how much compression is lost from cold to hot as well as that's always a factor for a "hot" start...