Hello everyone. New guy to the forum here, hoping for a little advice. I have a 98 Sportsman 500 that i have been trying to get running steady. It starts sometimes and then you shut it off it wont start again. Getting great spark, and it runs great when it starts. However when it was running I drove it around the driveway for roughfly 3 minutes and pulled the plug and it was running lean. So i cleaned the carb and made sure everything was adjusted to dealer specs, and did not make a difference.I am kind of new to this style carb, but wondering about the vacume coming from the pump,could there be something to look at there? Like I said any advice would be highly appreciated. Thanks In advance.

 

Unlike sleds that use slide carbs the ATV use CV carbs here is a good link on how they work Care & Feeding Of The Keihin Carb they have a air tight seal between it and the motor intake and to the air box.

 

Well it does not sound like that is my problem. It does not sound like the carb would be inconsistant like that. It just seemss like it looses prime or something. I can let it sit there and idle for 5 mins, shut it off and turn it right back on and it wont start, just turnover and maybe a little backfire through the exaust. Thanks for the info on the carb, thats a great illustration.

 

almost sounds like the stator, when they get hot they won't send voltage to the ignition i've seen a lot of them do this when the motor cools it'll start when its running it won't stat running when warm

 

wonder if that has a bad cam as thats right around the right years they issues w/ them? if not maybe fuel pump is breaking down. imo.

 

Well I have been reading around the site about the bad cam era and the only thing that pulls me from that is when the four wheeler is running it runs great, probably to good cause it is running lean like i said. One would think that it would not run real good if the pump was breaking down also so i dont know. Think i might pull the fuel pump apart and see if anything looks out of place in there.

 

Check the fuel vent line first if it isnt plugged check valve clearance and cam for wear