Whenever I warm up my Eton Viper 50cc and adjust the carb for optimal running it won't start up the next day.

The manual says that the air/fuel mixture screw should be 3/4-1 1/4 turns out from bottom, but the ATV runs WAY too rich when it is at that point. When I adjust it I find that 2 1/2 to 3 turns runs great, so I set it to 2 turns for a richer mixture for cooler running. The problem is that I cannot start the quad after it cools down. It doesn't matter if the choke is off or on, I cannot get the thing to kick over. It just cranks and cranks with no sign of life. I have to turn the air/fuel mixture down to 1 1/4 turns to get it to start.

What could be the problem?

Thanks for your help.

loquist

 

I dont know about your carb, but the Mikuni on my 200CC Gio quad, as you turn the screw out, it gets richer, unless yours is an air metering jet, not a fuel metering jet.

Have you tried pulling the plug when it doesnt start? I wonder if it is getting too much fuel with the idle screw out that far?

 

Thanks for the reply.

Mine definitely is air metering. The quad runs rich with it turned in and runs leaner as it is turned out.

loquist