Hey Yall, need some help here. i have a 2001 sportsman 400 4x4 that won't run over 15 mph. the bike idles great,starts easy,but taking off from a dead stop it will spin tires and run great for 15 feet and the fall on it,s face spit and sputter.reverse gear is the effect. this is what i have tried to fix the problem, removed carb and cleaned,replaced needle and seat valve- was egg shaped. replaced coil,plug wire,plug boot.spark plug. new fuel and air filters,tested fuel pump-ok,checked drive and driven clutch pulleys-ok, adjusted choke cable and still can't find anything wrong. PLEASE HELP DON'T WANNA SELL BIKE

 

you said it acts like its in reverse when you push the throttle too far? did you try it in reverse and push the overirde to make it was working. what im wondering is it topping out the rpms and hitting the rev limiter because the secondary clutch isnt shifting out. you said you checked them, did you pull the secondary (driven) apart to check the ramps(buttons) on the inside where the helxi rides to see if there broke. just a thought.

 

howdy, yeah i took secondary drum apart and checked it all was ok, had extra buttons from a prior repair, installed anyway and no help, I've also removed the muffler and ran it,no help, it gets worse when engine is warmed up, removed rocker cover and inspected camshaft,adjusted valves all was fine there I'm running out of ideas.

 

seems like that leaves an electrical problem?? maybe override is messing up so it kicks the rev. limiter in. just an idear.

 

I'm hoping it something electrical. is any to test that stuff? what is the little box underneth the ign coil maybe timing module? there is another box up front right behind the radiator ,any idea what that is.

 

does it run well when you give it gas in nuetral? or does it only do this under load?
i would take the time to check the exhaust lobe on your camshaft. i just replaced my cam last week cause the exhaust lobe was almost totally wore down, it was causing the quad to spit and sputter at about half throttle, just a suggestion

 

I have had two problems like that on 2004 400 sp the first one would do like that it was the vent line off carb dirt dobbers had them pluged sound werd but it happened. try to see if it goes dead when turning the handle bar to left or right i had one that had a wire almost in two that when you turn to right it would die at any speed.

 

howdy yall, the bike acts the same in neutral and in gear,lots more noticeable when engine is warmed up . when cold the bike runs fair, but as it heats up it gets worse. could there be a control box warming up and causing the spark too fade away. i put a brand new spark plug in and ran the bike with the throttle pinned aprox 1/4 mile, pulled the plug and it was carboned black, but not fuel wet. the cam and rocker arms all looked good. i have less than 1100 miles one the bike and it gets run hard at times but not abused, and it does putt putt round the farm too.. thanks

 

[img]i/expressions/face-icon-small-happy.gif[/img]hey again finnally . i fixed the damn thing, CDI box was bad. found an aftermarket one online put it in and the bike runs great. thanks for all the help yall!!!