98 yz400f hot start porblem

4 replies to this topic
  • kountry37

Posted February 25, 2010 - 06:15 PM


i just got a 98 (or 99) yz400. it starts and runs alright. the problem is that it only starts and runs with the hot start pulled out (or active). it will not start without the hot start on and when warm, you can push it in, but it acts as though it's not idled up high enough and dies. the problem is that it's idled up all the way and i just cleaned the main jet, pilot jet, and the float bowl. i'm stumped on this situation and need help...

  • kountry37

Posted March 18, 2010 - 04:29 PM


think it may need the next size up pilot jet????????

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  • JandJ07

Posted March 18, 2010 - 04:41 PM


Have you checked the pilot screw adjustment?

  • kountry37

Posted March 18, 2010 - 06:45 PM


i cleaned out the pilot jet a few weeks ago. when i put it back in, i just made sure it was snug. is there a specific adjustment for it?

  • kountry37

Posted March 28, 2010 - 08:40 AM


ok i'm an idiot. i found the manual and had the hot start and choke mixed up. it has to run with the choke out, not the hot start. i did set the pilot jet setting on the carb back to factory spec. still no luck......

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