Hey everyone. I'm new here to the forums but I'm always on here getting some ideas. Anyway, I have an 03 raptor 660 that won't start. I pulled the plug and I'm getting good spark. I took the carbs off and cleaned them and they're getting fuel. I put a small amount of gas in the plug and even used starting fluid in the carbs but all she does is crank and backfire once in a while? Does anyone know if the cdi would be bad even though I'm still getting a good spark? I checked all the grounds and the wiring and everything is plugged in and all grounds are good. If any of you guys have any ideas or suggestions it would be greatly appreciated since I'm at a loss. Thanks guys.
Anthony

 

The last component required for ignition--compression. Check your compression and then we will go from there.

 

what brought this problem on and did you adjust the intake valves lately?

 

Try adjusting your valves.