have new plug and runs great but have slight back fire is this from timing or what any info would be nice and on the radiater there is a senser has 2 wires going to it a blue and white wire what side does which go on

 

I dont know if this helps but my quad ran fine and then on day was back fireing like hell and the problem was my header was lose. Fix that and run like a champ now never better.

 

you could turn the mixture screw both ways until it gets better

 

well whitch way in for lean or what is it out for lean or in for rich wich way please cant remember

 

jetting 101- on a four stroke the screw adds fuel as you turn out, 2-stroke adds air when you turn out. next thing,the SENSOR you speak of is the temp. switch to turn on electric fan.doesnt matter which way,when it gets hot circuit closes and fan comes on. CLASS DISMISSED ! just kiddin[img]i/expressions/face-icon-small-cool.gif[/img]