I have a 98 Grizzly 600. It will idol but when I give it throttle it does not rev up. When I put it in gear, I'm lucky if it will go 10 mph and it does not back fire. Any ideas please.

 

First check for a restriction in gas line to carb. More likely dirt or gunk in the carb. Take the carb apart, clean it really well, blow out all jets, check the function of the float, and float height. If it's not opening enough, it will run out of gas very quickly. Check the function of the needle and slide, that they slide easily and are not stuck.If you don't feel comfortable tearing in to it, take it to a mechanic that has experience tuning carbs, even a Harley guy should be able to do that. I can't imagine, an experienced mechanic taking more than an hour. Of course, check the spark plug's condition, and replace if it looks suspicious. When I bought my 2001 Arctic Cat 500, the gas tank looked like a mouse had made a nest in it. Previous owner thought the motor was bad, nope. What a PITA, that crud in the tank was! It would idle, but backfire and not run over 10 mph...