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09' YZ250F Intake/Exhaust Problems

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I bought this bike recently, and it is my first dirt bike (raptor 350 prior), so I am new to some of the aspects of a race made motor.

 

I noticed the backfiring right when I got it, and thought I could fix it without first seeing if this is a common issue.  It came with a FMF Factory 4.1 exhaust and I determined the issue to be running lean.

 

I cleaned out the carb, put in a large main jet (180) and began the problems.

 

It does not idle very well, as it idled much better before I messed up by trying to fix a normal backfire.  I am not what it is called, but the bike has two idle speeds, and it has been idleing in the fast idle speed only.  When I ride the bike, it doesn't idle high when I'm off the throttle.

 

Also when running the bike in my garage, seeing how long I could let it idle, the header became extremely hot.  In face it was glowing red.  This does not happen when I am riding, probably because the air is then cooling it.

 

I also have a slight bog when creeping in a gear to hitting the throttle.  I am not sure if this is normal, but I would like to know if it isn't.

 

Any help is appreciated, I know many others have the same thread with similar issues, but I thought it is important to state the specifics of my problems.  Thank you in advance.

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Main jet is wide open throttle only

Your issue is the pilot jet, the passage above it, the fuel screw, and the hot start

 

You must clean the passage with fishing line and spray cleaner, and remove your hot start, polish the cavity and plunger, and re-grease

The hot start nut is often cracked, which you can replace with a Zip Ty aluminum nut.

When done, install a new R&D fuel screw

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