I have a 1994 (pretty sure on the year) Sportsman 400 2 storke that started running poorly. The symptom is you take off and as you increase speed it would start to pop and miss as if it was starving for fuel or perhaps getting too much I tried openign the choke to see if any different and not really. It smokes more than my otehr 2 strokes so I assumed the carb needed a rebuild. It was a bit dirty and needle and seat were questionable so we replaced them.

Took for a couple spins (.25 mile and some power takeoffs) and all seemed well and was not smoking as much.

Also the key and run switch are intermittent for shuttign off and we could not figure out why so we decided to add a toggle kill switch. We could only get it to work if we made pig tail and connected to the wire harness that appears to go to perhaps an ignition module?? but that seemd to casue it to run poorly again so we took it off. Now it seemed to run fine again.

Went to take another spin that same day and same problem sputtering and spitting and pretty smoky too.

Any clue?
New to this forum and appreciate the help to a new member.

 

First thing I'd do is a compression test. At least this will tell you where you stand on at least top end wise. Could be a mechanical,carb or electrical problem such as needing a new ignition switch or the etc contacts in the throttle could be touching if you have more than 1/8" slack in the thumb throttle. Cable adjuster is behind the boot on the throttle housing.Plus on this model there is a reverse limiter module under the headlight panel that can short out and limit. Pull the black wire from it and see if it helps. Item #41. http://www.cyclepartswarehouse.com/f...1994&fveh=5383

 

Thank you for the advice, I will start with checking the throttle then progress from there.

 

Old Polaris Tech -
I couldn't find my compression tester so I went to step 2 electronic throttle control and found a ton of play so I snugged it up but still no difference. It actually backfired on me twice each time blowing the exhaust off the head (never seen that before )
I also can't figure out why the key and on/off switch won't work which leads me to believe I have an electrical problem which is possibly causing the poor running and backfire - your thoughts?

When you say new ignition switch are you talking about the physical switch on the left bat or a module under the front light?

Trying to avoid trial and error on electrical

Thanks again for your help!

 

Pull the black wire from the limiter module on the link I mentioned in the first post and see if this solves the back firing and blowing the exhaust head pipe off. The limiter module if shorted out can do this plus also the contact points of the etc switch(in the throttle housing) if touching can retard spark and create the bang and popping back through the exhaust especially if you throttle up the machine and let off quickly. Pull the throttle housing cover off and make sure the contacts are not touching with no pressure on the throttle.If they are,just take a little more slack up on the cable. On not being able to kill the machine check that the black wire from the cdi module is hooked up. This wire also ties into the ignition switch and emergency kill switch(left control) and is the main kill circuit wire.