I have an 03 Rancher that I just picked up and it is giving me a fit! I just put in a new piston and rings but when I go to crank it up it wants to pop! It backfires and pops then smooths out then does it again or even dies! It has a brand new carb on it and I cleaned out the tank just for good measure! It sometimes idles high then it dies down then pops and backfires again! It's driving me crazy lol! Any help would be great thanks!!

 

Fit a new plug, or put the old one back in if it has a new plug. If that is a new Chinese carb, it may not be right, a good clean of the old one is a better bet. Check the voltage across the battery with engine running, it shouldn't go over 14.5v.

 

I am getting 13.6 volts while it's running. It is a cheap carb from ebay and your right I think I will go ahead and clean the old carb. It will now idle fine as it should but if you give it any throttle it just dies so I reached inside and pulled up the cv and it allowed me to rev the engine for the first time but it did blow back fuel through the carb at me while doing so! I am moving forward but at a snails pace! Thanks for the reply Merryman and the info I really appreciate the quick response!

 

They all spit fuel when running, you just don't notice unless you have the airbox off. I assume the fuel is sucked back in on the next inlet stroke.