Sputtering and backfire on a 03 Kawasaki 360 Prairie

[Samuel Jerome Morris]

I bought a 360 prairie that was having a problem with a backfire through the carb . The thing is making me crazy ! I have changed plugs , coil ,cleaned the fuel tank , rebuilt the carb 2 times and tried another on it that ran fine , checked the valves and finally changed the head thinking it might be a valve because when I got it it had a bad intake boot which I changed . Nothing has helped so far . Anyone have any ideas other than a gallon of gas and a match lol .

[Samuel Jerome Morris]

It does idle like a champ just can't push the throttle without the backfire .

[CunningStunt]

run it for a bit and remove the spark plug and describe exactly what color the spark plug tip is.  This to me sounds like the carb jets and air/fuel mixture settings are just out whack

[Ahren Longo]

Sputter and backfire usually means that its running too lean. It may have the wrong size jets in it but probably not. If you ran it with another carb and it ran fine it sounds like there may still be some trash in the main jets. Did you use a torch file on the jets when you cleaned it out? What kind of carb does it have? Does it have a butterfly or a piston type? If it has the butterfly type the main jet is partially blocked. If its the piston type then there is a needle that travels up and down in a sleeve with different size holes up and down the sleeve allowing more gas to get pulled through the higher the needle is. You can rebuild the carb as many times as you want but if you don't run a file through the jets you'll never get them clear and it'll still run like crap.