i am pretty much lost now. I have an 01 mxz 600. the sled idles just fine but as you press the throttle it will begin to move forward and then bog down. i will allow it to again idle and then try again and it will just bog down again. but, if i pump the throttle it will go until the rpms get pretty high and then bog down again. i can not open up the sled down the trail without it bogging. From what people have told me, it is most likely the carbs. the problem is that i have cleaned the carbs 3 times now! they are spotless. i then guessed it was bad fuel. i drained all the fuel and replaced it the fresh gas. the spark plugs are new. same result. i have no clue what is going on, any ideas? i did mess with the air mixture screw on carbs. the sled does have a brand new track i put on this summer, but it is not too tight so i dont see how it would effect anything.