I have a 1999 Polaris Sportsman 335 that runs fine until I push it full throttle, then it cuts out. Up to 3/4 throttle it is fine. Any ideas what the problem might be?
Thanks

 

Does it do this only in gear or does it in neutral also?

My first impression was the electronic throttle control stop is being activated---
secondary-- carb issues.

 

sounds like its straving it for fuel on tyop end maybe because the main jet is getting plugged or the float level is too low.

 

It only does it when it is in gear.

 

If it's fine up to 3/4 throttle, check your main jet.

 

There was a tsb on those models. If it has not been done, cut about 3/4 inch off the end of the snorkal and change the angle a little. Sounds like the snorkal is getting pushed up against the gas tank while you are sitting on it and its starving for air. it already is very close and when you open the throttle, it sucks the intake snorkal up against the gas tank and restricts air flow. When you let off it has enough air. If this has been done already, disreguard this. Don't just take the lid off and try it and try it, it won't run right without the lid on either.

 

is the vent tube blowing any oil into the air box?

 

hey, I am experiencing this issue. My 1999 polaris sportsman 335 started losing power and stalling out when I would be full throttle or pushing snow. Took the seat off and noticed the air box was broken and the hose was disconnected. The box had oil in it. Replaced the air box, lid, filter breather and spark plug. Now it idles fine and seems ok at 3/4 throttle but then it cuts out. Any ideas?