Hey guys, I'm a new at this so I need a little help. My quad started breaking up at 1/2 throtle. It starts and runs normal up to 1/2 throtle. I rebuilt the whole carb, changed out the fuel lines and vacumn lines, checked the vent on the fuel cap, cleaned all the electrical conections and changed the fuel petcock. It still breaks up at 1/2 throtle. So ,I ask of you , whats next? I'd appreciate any ideas you may have. Thanks, gerry

 

It sounds like the main jet in the carb is plugged up even after your "rebuild" because the main jet is not used until about 1/2 throttle.

So remove the main jet, blow it out with compressed air or stick something through it, then look through it to make sure it's not obstructed. Also check your float height. If the float is too low (stops fuel from flowing into the bowl before it's full enough), that could also cause it to cut out.

The proper specs & procedure for checking the float height is in the factory service manual, which is about a $50 investment; or you can take it to a shop for $50/hr!

If that doesn't fix your problem, I would suspect the ignition/cdi (whatever you want to call it) is going out.