I recently bought a predator 90cc that runs great but randomly bogs out or seems to shut down usually going fast around a certain corner. Sometimes it will sputter and backfire once and then run fine for a while. When it is bogging out and I try to give it gas, it just bogs more. Sometimes it will kill but will start right up and run fine. I checked the spark plugs and it shows light tan, replaced the spark plug and coil and it didn't make a difference. It has an after market exhaust, air filter and the Jets have been changed to compensate. I have read a ton of post but wasn't sure ware to start as I haven't read one that's doing the same thing as mine. Any help would be much appreciated!

 

If the carb has a bowl it could be:
1) The wet float level is set too low...causing starvation when fuel demand is highest
2) Blockage somewhere not allowing enough fuel to the bowl...again causing starvation


At least that's what your symptoms are telling me...

 

Yup, clean that carb.

 

Thanks for replying to my post so fast! The first thing I did was clean he carb and had to put a bigger pilot jet in because it was back firing alot and the fuel mixture screw was turned in all the way. I will try to set the floats Tonite and see what happens.

 

So...generally...turning in the A/F screw leans out the mixture...turning it out richens it...so not sure your problem was main jet size...unless that machine is heavily modified I'd find out stock jet sizes and start there as a baseline (A/F screw out 2 to 2.5 turns from lightly seated)...