99' yzf pilot size?

4 replies to this topic
  • ETS

Posted December 19, 2001 - 05:11 AM


I can't remember what pilot comes stock in my 99' but I have replaced it at one point with a 45 and every since then it takes quite a few blips on the throttle before it will fire. Is this normal? I'm guessing it's to lean and needs the blips to get the fuel in there. It runs good otherwise. Any other words of wisdom to cure the blipping throttle to start it. A friends 98' always fires right up but mine never likes to light and it usually takes a couple tries before it will finally stay running. Thanks

  • #302

Posted December 19, 2001 - 10:19 PM


the stock pilot jet size for a 99 yzf400 is a 45 and a general rule of thumb when you attempt to start your bike don't give it any gas.

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  • PK

Posted December 19, 2001 - 02:54 PM


I had to change my pilot jet to a 48 (next size richer) due to popping when decelerating and hard to start as it got colder. It helped quite a bit compared to the stock 45 jet.

99 YZ400

  • ETS

Posted December 20, 2001 - 04:17 AM


Well Mine won't start unless I give it at least two blips, kick a couple times and if it doesn't at least fire then I give it two more and so on until it fires. Usually 4 kicks in the summer and 10 in the fall and spring. It also will die a couple times when it's cold out before it stays running.

  • MN_Kevin

Posted December 20, 2001 - 05:36 AM


have you guys done a "SUPER CLEANING" of your carbs lately?

The 99 is NOTORIOUS for fouling it's accelerator pump diaphragm.

One TTer also mentioned his air jets (Pilot and Main AIR JETS/air ports-under the intake horn) were fouled w/ filter oil.

This IS on my list before the MAJOR carb re-jetting takes place.

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