I am trying to revive a Sportsman 400 2-stroke but I am having a few problems. It was sitting up for a while so I cleaned carb and drained gas. After installing the carb, the engine takes a minute to start up and it will only start if I give it throttle and pull the choke in and out. After it does finally start it jumps to almost wide open throttle without the throttle being pressed. I have checked the throttle cable and it seems to be free moving and I have the idle screw backed almost all the way out, but still no change. When it does this, I cannot kill it. I turn the key off and switch the kill switch and it keeps running. The only way it stops is if I hit the throttle and then kill it. I am not sure if it is the etc and if so how do I test it or if the slide is not closing in the carb. any help or ideas would be appreciated. I need a fresh set of eyes ob this problem

 

when you put the slide back in the carb is it in the correct way and not backwards? you should be able to look in the throat of the carb and see if the slide is all the way down. also make sure you don't have an air leak and it's sucking air which would count for the idle going up.

 

thanks for the reply stendori. I know the slide is in correctly, because it will only go in one way. I will pull it and check again. I will also check for air leak. I will post my finding. If anyone else has some ideas, let me know.

 

I have corrected the throttle problem, but now there is a new problem. I have to choke it to crank it every time and the only way to keep it running is to apply some throttle. Then when I press the throttle down to rev the engine it tries to bog down and I have release and hit the throttle again for it to rev up. I have tried the idle screw and the adjustment on the etc and adjustment on the slide, but none seem to have any effect on the idle. The engine actually sounds good when it does finally rev. Any help would be appreciated.

 

Sounds like you still have some type of blockage in the carb from the old gas/varnish. I'd try taking it apart again, soak it over night in carb cleaner and then blow every passage with compressed air before reassembly. If that doesn't work, I'd get a rebuild kit and start fresh with factory settings/adjustments....

 

Did you take the pilot jet out and clean ALL the holes out

 

I re-cleaned the carb and put fresh gas in it and it fired right up and I adjusted the idle screw and all seem to come together until i test drove it. I t was running fine, but all of the sudden it just died while doing about 30 mph and would not fire back up. I have yet had time to check things out, but I am assuming this is steaming from the other problems. I ll keep ya'll updated on my progress and if anyone has any ideas, i would appreciate it. Thanks for the feedback so far.

 

take the gas cap off and see if it still does it.If it clears up you have a plugged or pinched vent line

 

This could also be caused by the needle and seat. I expierienced the exact same issue. the carb is flooding, but you cant see it while running because the vacume from the motor is drawing it into the cylinder, and causing it to foul the plug. change the needle and seat. Another good reason to do this, is that the factory seat is brass, the replacement seat is stainless, and will wear better.