Bike won't run properly after oil change.

I know this post is old, but if you ONLY did an oil change and wash job there should be no water in your carb. thats alot of water to fill the exhaust all the way back to the carb,(and past five valves!) You got some water....might be very little... on the spark plug boot(down at the plug), it only takes a little moisture to get a misfire. remember the spark will always go to the place with least resistance.

It's quite possible and not un-common to get water into your intake, in the air box and through the filter during an agressive wash. We weren't talking or referring to getting water in the carb through the exhaust opening on the can/muffler.

The OP started the thread 2 weeks ago, and is still trying to find a solution to his problem.

You do know there's a drain port in the spark plug well, don't you?

This has been a problem for other posters, and it was so easy, made for a real " I never thought of remembering that?" kind of epiphany.

Try with your gas cap off, or the vent line off. That can and will cause the symptoms your having. If you have ridden it since then, which you have not, it would have stalled as well. If the one way check valve in the vent line, line itself is clogged (or top hat vent like I have had go bad) it will stick and clog, and it will hold back enough fuel by vacuum to cause the engine to stumble like this and stall because gravity will not be enough to fill the float. It has even caused FI issues as well by holding back volume of fuel to the pump input after 60 sec or more.

The second one involved my own bike, and that was a stator in my 2008 KX450F. It never overheated, but all KX450F run hot and well, repeated heat cycles, time, caused mine to lose magnetism, even after everyone claimed mine was a fixed stator, or shouldn't happen with my version stator and year bike, it still happened. Would start some times one or two kicks, run and stall, flame out way too many times. Other symptoms as well.

New stator and the bike kicked tail once more, and never had an issue since. Also take your ECU out and check for cracks in the epoxy from time, that water may have seeped in through and for any cracks or shorting of your coil and high tension sparkplug lead. I doubt this would be an issue though.

Try a new stator from a dealer and check the gas cap vent.

Sorry for the delayed update, but I've had friends in town, and my ankle is still bugging me. Anyway, took the whole carb apart and cleaned it top to bottom, and installed a new pilot jet. The carb seemed very clean inside, but what they Hell. Bike started after a few kicks (could be due to my ankle as it's still twisted) and at first had a lumpy idle. Took it for a quick spin and when I got back and set the idle it seemed perfect again. I'll try it again in the next few days and update...

Sounds good, keep us posted....


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