I have an 05 Sportsman 400 that has been pretty reliable over the years. I noticed after a 60 mile ride a couple of weeks ago that I needed really high rpm's for it work properly in high gear. Seems that it starts out slow and then when the rpm's get high enough it takes off. It also seem to be really hot.

I took it to the dealership to have it's preventative maintenance done. All fluids and filters were changed. They also said that the ECM needed to be changed out. The ECM was covered under the recall.

I took it out again today for the first time. We drove 30 miles or so and the high gear problem seemed to still be there. The warning the light popped on and said the machine was "Hot. Check Engine" I shut down the machine, it did not appear to be overheating. The cap was cool to the touch. When I restarted it after 30 minutes, it would only go in low gear, but rev'd really high. After a little bit, I tried the high gear again, but struggled to move the machine.

Needless to say, we towed the atv 15 miles out to the next trailhead.

Any help would be appreciated.

 

If the rad is cool r lower hose but the temp light comes on then you either have a bad thermostat or you need to bleed the air out of your coolant system.

 

aswell make sure you rad isnt full of crap plugging the fins

 

Sounds to me like you also might need a new belt. Your old belt will get narrower over time making the clutch pinch tighter to grab it better. Hence "works better at high rpms".

 

I had a problem like this a month ago, I replaced the sensor, rebuilt the water pump and the rad which I thought was clean wasn't. When I held a light behind the rad I couldn't see light so I spent 3 hours after I took the fan out cleaning the rad from both sides and now when I hold a light behind it I can see clear as day through the fins and after all that my bike doesn't flash hot anymore.