hybrid will not start

[atvfreak400]

I was just pitting the finishing touches on my yz426 hybrid and I thought I would start it and to my surprize it wouldn't start ,it had been starting ok and was running[not well] but today it wouldn't even try,it was just loading the cylinder up with fuel and after a bit it would let out a back fire,the only thing that I did differently was I put a cut down yz muffler on it witch should not have any effect on it, it was fairly warm out today about 40-45[live in canada] any help would be great.

[Rip_Tear]

Might have to rejet, and I don't know F, but it was about 0 or +1ish C today here, and really moist. I have problems sometimes in the winter when it's so wet out.

[2muchquad]

your plug is fouled,i know it sounds elementary but ias a owner of a yz426 myself,they do foul plugs on occassion.if you have bad valve seals they will leak oil into the cylinder when you shut it off and the next time you go to ride it will fire up and quit,game over.you can kick til your blue in the face:D for cold starting,find tdc,3 stabs of the throttle and it should fire in 1 or 2 kicks.

[ss440ex]

Replace your spark plug.

[KY Woods Rider]

You said it hadn't been running well even when you had it running previously, so curiosity would have me inspecting the valve clearances, if for nothing more than just peace of mind.

[atvfreak400]

well I will change the plug and see what that does,I did'n have one here so I was just cleaning the old one,but I will go and buy a new one and see what happens thanks

[redrider311]

i have to agree.. if it runs after you change your plug if i were you id still take the 40 mintues to adjust your valves back..