Bike just stopped running mid day

I’m baffled by this. So as I’m prepping my 2000 KDX to run a hare scramble this weekend, I started the bike and it ran on the 3rd kick after sitting over the winter. I let it warm up, ran it around the yard, then drained the oil. I filled the oil back up and it hasn’t run since. Here is what I then did and what I observed:

• Put new spark plug in; confirmed it was getting spark.
• Drained the carb bowl, cleaned the bowl, removed and blew out the main jet and pilot jet; then generally cleaned the carb.
• Cleaned the air filter and air box (I occasionally get a mouse nest at the bottom of the air box over winter) – confirmed it had clean path to the carb.
• Drained the gas and replaced with fresh Premium gas and premix.
• Confirmed the gas ran through the petcock and into the carb.
• As I kicked and kicked with no start, I noticed unspent gas/oil leaking from the exhaust pipe head (where it connects to the cylinder) – I probably need a new gasket/washer, but I have seen that before and bike still ran fine. So I took off exhaust pipe, cleaned it and put back.
• I noticed some carbon build up at the exhaust port and a little bit of black on the piston just under the rings.

The most baffling thing is, the bike was running perfect until I changed oil. Now it doesn’t even sound like it wants to turn over; like it’s not getting any spark, gas and/or air. I did the top end many years ago and the bike has always started in the first 5-10 kicks all these years. It’s never just stopped running after running earlier; it’s been pretty bulletproof all these years.

I’m trying to get it running before Sunday; any insight is greatly appreciated. Thanks in advance.

RM_guy said:

That is an odd one. Could it just be badly flooded? Gas leaking out the cylinder makes me think that. Try to shut off the gas, hold the throttle wide open and kick it over as may time as you can. Good luck!

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Thanks RM-guy...I will def give that a try when I get home today. My brain hurts trying to solve this one.....I'm out of ideas!

cheapo said:

Thanks RM-guy...I will def give that a try when I get home today. My brain hurts trying to solve this one.....I'm out of ideas!

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After +/- 7 hrs of tearing things down, cleaning, diagnosing, etc....RM_guy, looks like you were right! File this under, Keep It Simple Stupid. I pulled the plug, kicked it to get some of the gas out of the cylinder, put new plug back in, turned gas off, opened throttle and after numerous kicks, she showed some life, then started. It really was just flooded. Thanks again!

Yes! My mind sometimes goes to the most complicated of solutions whereas I should be working the other way. Thanks again - I now know.