KX65 Won't Idle

[dog2]

My sons 2002 KX65 won't idle or run below 2,000 RPM. It won't start with the kickstarter (only push starting). The bike has run perfectly until this weekend. We have gone throught he carburetor twice. Carb was clean, no blockage, or debris. All of the passage ways were blown out with compresssed air and carb cleaner.

The plug is dry and not fouling. It is getting spark when checked with the plug out. New spark plug made no changed.
It runs fine at high RPM and high throttle, until somewhere down around 2,000 RPM and then it will die and won't restart.

I orginally thought the idle circuit was plugged, but now I suspect something in the ignition. Has anyone had this before?
Thanks

 

[Jasle]

when you say it won't restart...how long til it will or what do you do to eventually get it to start? I have seen symptoms like this and swore up and down it was not the carb because I have cleaned it to no end. then I swapped ignitions and the problem still existed. Swapped carbies and it went away. Soaked carb overnight in auto solution you buy in the can and voila the problem went away.
I could see your problems being ignition related. You can buy one of those cheap 3$ spark testers at the auto store. They go between the plug wire and the plug and flash everyitme their is spark. If the spare goes away at low rpm then you found your cluprit.
You'd have to have a weak stator that drops out when the rotor isn't spinning fast enough to create a spike to the coil...Not very probably as stators usually short out stragiht away but plasuabile for sure.

 

[dog2]

Thanks for the input. I am really scratching my head trying to figure out this one...

I could get it started by pushing it really fast, dumping the clutch in second gear, to get the motor spun up. If I could keep it at fairly high RPM it would keep running.

I checked the spark, just by kick starting with the plug grounded to the outside of the cylinder. It is getting spark. It may be a little week, but it is hard to tell.

Also, when trying to kick start it, there is no signs of life. In other words, no pops, backfires, or half-starts. Completely dead.

The spark plugs are dry. No sign of fouling. Like your post, I hate to start buying ignition parts only to find out it was something else.

I was hoping someone had this same problem and could identify the root cause. I will keep doing some tests, but if anyone had more ideas, let me know.

 

[Jasle]

check compression and reeds. if they reeds are hammered it makes starting and bottom end poor

 

[jesse glenn]

Mod Edit - If you SPAM once more in these forums your account will be removed.

 

[Vytas]

I saw a problem like this at the track on a KX60.  The bike would run when revving but had no idle.  After cleaning carb, checking timing and alot of head scratching the problem was found.  The ignition coil was loose on the mount.  At high rpm's it made contact, therefore you had a ground.  At low rpm the connection was intermittent - no/or poor ground.  Check your frame grounds, sand clean and use some dielectric grease to ensure a good connection.  Hope this helps.

 

[dog2]

Just in case anyone searches on this problem, I wanted to conclude the issue.

The problem turned out to be damages piston and rings from siezing. Althouth it still showed pretty good compression with a compression tester, the rings were stuck on the exhaust side from seizing at some point in it's life. New piston and rings and everything is running strong.