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crprestridge

2005 Yamaha yfz450 running lean, i think?

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i own a 2005 yfz 450 and i think it's running lean. when i get 3/4 to wide open it misses or cuts out. i have a k and n filter, yosh exhaust sytem and is jetted with a moose racing jet kit. main jet is dj132, pilot jet is dpjm048 and needle is set on #4. the fuel aire mixture screw was 1 and a 1/2 turns out but now 2 turns. spark plug is white. what should i do now?

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Put a bigger main jet it. What size jets did the kit come with(I'm not familiar with moose brand jets)? The 48p sounds like a normal size, but I'm not sure about main. I used a gytr jet kit that came with my pipe and use main jets between 165-170 and pilots 45 or 48. If you'r screw is out 3 or more turns, you need a bigger jet.

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i own a 2005 yfz 450 and i think it's running lean. when i get 3/4 to wide open it misses or cuts out. i have a k and n filter, yosh exhaust sytem and is jetted with a moose racing jet kit. main jet is dj132, pilot jet is dpjm048 and needle is set on #4. the fuel aire mixture screw was 1 and a 1/2 turns out but now 2 turns. spark plug is white. what should i do now?

Did any of the Suggestions fix your problem.....Everyone was right on top of it.....

Your Main jet Controls 3/4 to WOT......

Also,,,,,,,Make sure that the Float is set right..... To high will make it run Rich....Too low will make it run lean....When you do plug Chops......Make sure you use a new Spark Plug, Clean Air Filter and New Gas....If you can figure out a way to mark the 4 Different Positions of your Throttle location when you are Tuning it will be easier to identify the problem area for jetting....

The air screw is most effective between idle through 1/8 throttle.

The pilot (slow) jet 1/8 through 1/4 throttle.

The slide 1/8 through 1/2 throttle

The jet needle 1/4 through 3/4 throttle.

The main jet 3/4 through wide-open throttle

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Check how you have you slide installed compare it to a service manual diagram. The design Yamaha used makes it easy to put the slide plates in backwards or upside down either way you'll get erratic running issues.

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Guest michealwaiting

Was curious if it got better?

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i had a friend of mine re-jet the carb. but yes, it is running alot better. done a few more things to it since but still haven't gone into the motor except to degree the exhaust cam back a bit.

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i had a friend of mine re-jet the carb. but yes, it is running alot better. done a few more things to it since but still haven't gone into the motor except to degree the exhaust cam back a bit.

Glad to hear you solved your by re-jetting the carb. Did you install a larger main jet?

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