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big bear 400 miss fire when cold

gangle04

By gangle04
in Yamaha ATV Forum

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gangle04 Explorer

gangle04

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Dont kno if i would exactly call it a missfire but sometimes when i fist get on my quad( after letting it warm up with choke for five mins ) and rip away usually right after shifting it will miss 1 spark blow that air/fuel into exhaust and backfire then run normal sometimes itll do this 2-3 times aways in the beginning of a ride usually if i warm it up a little less then usual, just curious what would cause this. It did it since i got the quad 6 months ago and theres a different head cyl. And piston in it now...also what would cause oil to stop flowing into a head??? Or did i screw something up??? On the new head i noticed oil poors out behind cam sprocket on the old one it didnt

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