i recently bought 2 atvs. a 1997 yamaha banshee for myself and a 1999 yamaha bear tracker for my wife. the banshee has been great but i have been having problems with the bear tracker.
it starts great, idles great, but when i am driving it, it seems to bog down alot. you cant really get going very easily. if you give it any more then about 1/4 throttle it just stumbles very badly, but once you let off the gas it does great.
without the choke out, it stumbles even worse, but with the choke half way, it does a little better.
could this just be as simple as a dirty carb, or an adjustment???
im new to working on atv's, and these are my 1st ones, so im not sure whats going on. any help would be greatly appreciated before my wife gets mad at me.
thanks

 

sounds like a dirty carb. i would take it out and clean it real good and see what happens. then try your adjustments if that isn't it.

 

thanks for the reply, the other problem is that i dont know how to adjust anything on the carb except for the idle

 

may be the main jet clogged up.Take carb off or turn it to where you can get the bowl off the bottom of the carb(usually 4 screws hold it on).when you get the bowl off there will be two jets you can screw all the way out.One jet will have a bigger hole,this one will probably be the one clogged but while your in there go ahead and clean both of them out.I usually run a very small piece of wire through them to unclog them.

 

thanks. i will have to try that out tomorrow

 

Check the air filter,make sure its clean and in good condition. Change the spark plug with a new one thats gapped properly. If you don't want to tear into the carb, try mixing some SeaFoam in the gas, start the bike and let it idle a while. The carb could be just gummed up and not plugged up completely. Make sure the bike doesn't overheat while sitting still.