I have a 99 sportsman 500 here that needed a cam and a carb rebuild which I did. 2 weeks later it has some of the same symptoms it had before. At WOT it goes about 20 mph and surges alittle. Take the airbox off and it has all kinds of power. Even putting on the 2 inch long rubber hose that connects the carb to the air box makes it act up. I checked the valve clearances, timing, loosened the muffler, raised and lowered the clip on the needle. Nothing helped. There is nothing blocking the snorkle or airbox tube. A F is a KN with no prefilter. What am I missing?

 

Have you rejeted the carb. A K&N is a very free breathing filter that can require rejetting. If you have it it may also be that you haven't got the Air/fuel mix dialed in.

 

No i didnt rejet. And I am alittle skeptical about the kn, The thing is it ran great for two weeks

 

check your spark plug to see if its running rich. if running w/out the filter runs fine then sounds like it richens it right up w/ the filter back on.

 

Will it rev up in nuetral? Is it just doing this while riding? Might be the Buttons in the secondary clutch instead of the motor.

 

Thanks for the input guys
It does rev up in neutral but its choppy and inconsistant. I will check the plug again and reajust the mixture screw. I haven't done anything with the electronics either. thanks for the suggestions

 

How did you make out doc?

 

still puzzling it out. i found a crack in the tube between the air box and carb. a new one made no difference. the slider in the carb just doesn't seem to want to move. I took it all apart and cleaned it and now it runs good again. No idea why. I'm just waiting to see how long it lasts. what is the valve lash supposed to be? thanks guys

 

keep me updated...