new 04 yamaha yz 250 fouled two plugs already???

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Nov 2, 1999
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#1
hey guys i just bought a new 04 yz 250 and ive already foulded two brand new plugs riding around in front of my house here in Kentucky (elevation 1200 ft. temps about 50 degrees). What happened to that yamaha jetting being perfect? My new bike says NOT. Everything on the bike is stock....My cr 250 (99) ate plugs until i leaned the jetting considerably. I leaned the needle one clip on the new yz. I hope this cures the jetting problem. I thought i was getting rid of the jetting nightmare when i bought the yz...but at the present time it doesnt seem that way....any hints or advice on this bike's jetting would just make my day...
Thanks again.
Redrider
 

Y2Z

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#3
its normal while breaking in, my 02 yz125 did it, so did my friends. after i got some hours on it i havent fouled one since.
 
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#4
i guess I feel victim to what they say in the dirtbike mags...I know I should have known better. Thanks for the replies and info.
Redrider.
 
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#5
This probably isn't your problem, but make sure you warm up your bike completely before riding it. My 04 YZ 125 fouled a couple plugs, but after warming the bike up longer before riding, i haven't since had a problem.
 
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#6
I think that's true about warming it up longer. But that may be a float height problem if you have to let it idle for 3-5 minutes for it to run w/out fouling. That used to be my problem. If I took off only letting it idle for just a minute then it'd foul. I always used to foul them---if I could get past warm-up it'd run all day 100% perfect. If that sounds like you then you know your float height is too high. Just a thought.
 
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#7
REdRider you have some kinda problem.

My '04 YZ250 has been perfect, even when I ride waaayyy to high in elevation for stock jetting (up to 5,500').

No fouled plugs so far, running 30:1 premix......
 
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#8
I agree with rairden - check the float level. I had a similar problem with a 95 KX 250. Got the float back to spec, and the problem went away.
 
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#9
I will check the float level then let you know what that does...I was also considering using the next leaner pilot that came with the bike. I will also try letting the bike warm up longer...I will keep you informed...Thanks for the info.
Red (or blue...heck i dont know what I am) rider.
99 cr 250
2004 yz 250
wood riding only