400 Running Poorly

2 replies to this topic
  • Markopolo400

Posted June 05, 2008 - 04:54 PM


First and foremost, I race C class motocross, but I am pretty hard on my bikes. But I baby my bikes, heck, I spend more time working on them than I do riding them.

I brought my 1999 YZ400F out for practice last night, but as soon as I unloaded it, I started having problems. First it took forever to start, and when I did get it started, it just coughed and died.

I got it started again, after a zillion kicks, then warmed it up and did 1 straight a way, and it just sputtered and died. This was the story of last night, as it would take forever to start, then sputter and die a minute or two later.

I checked the plug and it was ok, and I put in all new valve/springs/keepers/seals (Etc), Piston, rings, and cam chain, only about 30 hours ago.

I am going to tear apart the carb and clean it, as I am guessing there is a speck of dirt in the pilot jet or something. Any other ideas?

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  • Markopolo400

Posted July 08, 2008 - 12:20 PM


I am finally getting around to working on my bike, and I am starting off by cleaning out the jets.

Anybody have any other ideas? I am going to check my valves while I have it all apart.

  • Markopolo400

Posted July 08, 2008 - 05:00 PM


I checked the valves and they were fine, I blew off the plug with compressed air, and I blew the entire carb out with compressed air.

I put in some new gas, and she is running great again.

Thanks for all the help guys. :thumbsup:

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