03 Yz 450f

11 replies to this topic
  • tpastrana

Posted June 11, 2010 - 10:51 AM


My bike seems like it runs way lean (backfires, and pops) when the hot start lever is in but when i pull it out it seems like its runnin fine, ive torn the carb apart two times and wondering if i missed cleaning a place any help is appreciated!

  • grayracer513

Posted June 11, 2010 - 12:16 PM


What color is the knob on your hot start lever?

  • tpastrana

Posted June 12, 2010 - 12:53 AM


the knob on the lever is black , its stock, and the I just bought a pro circuit hot start connector because the OEM one was stripped and thought it would fix it but it didn't :thumbsup:

  • wild west al

Posted June 12, 2010 - 02:28 AM


mmmmmmmm my hot start choke is red?

  • tpastrana

Posted June 12, 2010 - 11:05 AM


on the 03's they brought up the hot start to a lever on the handlebars

  • grayracer513

Posted June 12, 2010 - 05:18 PM


The knob is your choke, and your carb is running lean because of a partially blocked pilot jet or a stuck hot start, which is the aforementioned small lever on the clutch perch.

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  • tpastrana

Posted June 12, 2010 - 08:14 PM


Well pretty positive it isn't a stuck hot start, i pulled the jets out and they looked clean soaked them in gunk carb cleaner anyways but i can pull them out again.

  • grayracer513

Posted June 12, 2010 - 08:26 PM


The pilot screw is adjusted correctly? The O-ring is in place on the screw?

  • tpastrana

Posted June 13, 2010 - 08:49 AM


yes pilot jet is out 2 1/2 turns, yes the oring was in place last time I put the carb back

  • grayracer513

Posted June 13, 2010 - 11:06 AM


That's the pilot screw, not the pilot jet.

  • tpastrana

Posted June 13, 2010 - 12:32 PM


:thumbsup: crap oh yeah I had the dealer rebuild it, put high compression wiseco piston in, and rejetted it...how do you adjust the pilot jet? hmmm i'll pull it out and see if the is intact.

  • grayracer513

Posted June 13, 2010 - 02:02 PM


You adjust the pilot screw, not the jet:


The problem with the pilot jet is that the metering orifice is so small that any little bit of dried fuel varnish will cut the jet size by 3 or 4 steps even though it looks like it's open. The cross holes can also become clogged and are often overlooked.

Either clean it thoroughly ( http://www.thumperta...726#post8021726 ) or replace it.

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