07 450 - Idle goes up once engine is hot

6 replies to this topic
  • idahoexcr500

Posted July 11, 2011 - 07:57 AM


Hi All,

have done allot of searching trying to find an answer for this. My 07 450 has a weird issue where the idle is faster once the engine gets hot as compared to when it is first fired up and is warmed up.
Stock engine and jetting with DMC pipe/silencer. air screw at 2 1/4 turns out, twin air filter. Hot start is not sticking. Bike runs fine, just irritating having to turn the idle down once the engine is hot. Temps here are around 90F, elevation around 3 thousand feet.
Carb is clean, pilot jet is new.

Any ideas? thanks Dave

  • Family Man

Posted July 11, 2011 - 08:38 AM


Try a bigger main jet. check for leaks on the exhaust.

  • grayracer513

Posted July 11, 2011 - 09:01 AM


The main jet has no influence on the idle and and neither will an air leak in the exhaust system.

This is usually caused by a lean condition, which can be from a lean pilot, air leak at the fuel screw or at the intake spigot, or possibly a tight intake valve. Normally, they do idle better when fully warmed up, but there should only be a couple hundred RPM difference.

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  • idahoexcr500

Posted July 11, 2011 - 09:50 AM


Thanks for your comments. being too lean still, had not thought that would occur in these warmer temps. I had installed a 48 pilot in January because the bike was running to lean and backfiring allot in the 30 degree temps here at that time. The 48 fixed those issues. I was concerned it would be too rich for summer temps however. The bike did run fine with the 48 installed however, even in 70 degree temps in the spring. Valves have been adjusted recently and just replaced the fuel screw, spring, washer and o-ring installed in correct order. I will reinstall the 48 pilot and try things again.

  • grayracer513

Posted July 11, 2011 - 12:33 PM


What size is the current pilot?

  • idahoexcr500

Posted July 12, 2011 - 03:31 AM


I am running a stock 45 pilot currently/ Ran a 48 in the winter. stock engine.

  • grayracer513

Posted July 12, 2011 - 06:52 AM


The 45 should be right....

Never can tell

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