250F Why Won't My 2007 Yz250f Start?

AKmotorider

AKmotorider

I replaced the spark plug and checked for spark, which it has. I also did a compression test on it, which after about 20 kicks, read 75 psi and wouldnt go any higher. I'm guessing it has an auto decompressor so it wouldnt give an accurate reading, but is that normal compression if its autodecompressed? Or is it impossible to tell with a compression test? I have yet to do a leak-down test on it but from what I've heard it's a better idea than the compression test. If my compression comes out normal, then what else could be preventing my bike from starting?
 
josmoloco

josmoloco

If you are getting fuel(check carb and plug), Air(make sure passageways are open) and spark(check plug, make sure coil is good, as I had one fail on a yz250f) then check the valve clearance.
 
James

James

Staff member
Have you tried bump starting it?

Another option, though rare, is an electrical issue (CDI, wire harness).
 
bobkyle2

bobkyle2

Pull the spark plug out... Put the plug into the spark plug wire... Sit the spark plug against the head... And have someone kick the kick start...While you watch the spark plug. The spark plug should be sparking.

Don't touch the spark plug while you are kicking it. It could give you a shock :devil:
 
AKmotorider

AKmotorider

bobkyle2:
Pull the spark plug out... Put the plug into the spark plug wire... Sit the spark plug against the head... And have someone kick the kick start...While you watch the spark plug. The spark plug should be sparking.

Don't touch the spark plug while you are kicking it. It could give you a shock :devil:
Click to expand...
I did exactly that just today with a friend, and yes it sparked. He touched it while I kicked it and he got a good jolt lol. If you mean firing as in the sound like its trying to start, then yes, it has that sound when I kick it. Like it's almost starting but cant.
 
bobkyle2

bobkyle2

If it jolted.. Its firing. By firing i meant sparking.

Does it have fresh fuel?

When is the last time it ran?

What caused it not to run, Did it die? Did it just not start one day? Had you been riding it that day?
 
AKmotorider

AKmotorider

bobkyle2:
If it jolted.. Its firing. By firing i meant sparking.

Does it have fresh fuel?

When is the last time it ran?

What caused it not to run, Did it die? Did it just not start one day? Had you been riding it that day?
Click to expand...
A couple days ago I was riding it. It never died, it just got harder and harder to start every time I turned it off. For example, last tuesday it started easily, by thursday it was medium difficulty, but by sunday it was almost impossible.
Fresh fuel? Kind of. Like fresh as in maybe a 4-5 days old.
I rode it tues, thurs, friday, and sunday. Hour and half each day (approx.)
 
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