to all 650 ac owners i have a 04 500 ac that is doing the samething. i have had mine a the dealer 3 times in 3 months (once a month since i have had it ) the dealer cant find anything wrong either, i'am getting pissed also, i contacted arctic c at corp , they told me i can take it to another dealer if mine didnt get it fixed. maybe if more people contact the company something can get done. i have no idea about the check valve either , dont see anytrhing on my machine.


farmkid

 

I started this thread and haven't really had a chance to take the AC again since...November? (I really need to take it out and run!) I'm paying attention to all replies and it seems this may be a bigger issue than I thought. I'm still thinking my problem may be oil in the filter but it is up north and I haven't had a chance to check it.

 

Just a little note, last night we had my bud's 650 apart, looking for a fuel leak. We found that the choke plunger on the rear carb was stuck in its' bore, wouldn't move at all, and had the carb stuck with the choke partially on. This allowed it to idle off of that carb, and a little bit of adjustment on the idle adjustment screw would compensate for the front carb. . Once we took the choke plungers out, we could see that it was flooding the float bowl, then running down the choke cable and dripping out at the junction. Also, we took the throttle cable housing off, and with the idle adjustment screw turned all the way in (for fast idle) it was barely moving the throttle plates. We had to bend the tab to make it contact the adjustment screw at half way in, so we had some kind of idle adjustment.
After that, we got it started and noticed that the carb throttles were opening at different rates. The rear carb was opening first, followed by the front carb. You could see the rear diaphram moving while the front was still. They SHOULD move the same amount, simultaneously. We synchronized the throttle plates so that they opened together using the adjustment screw in between the carbs, and now had adjustment for idle speed as well. I don't think these carbs were set up from the factory, or even looked at prior to delivery, they just set the idle adjustment screw to get a half decent idle and left it at that. Really, you guys should check your carb set-up, I'm willing to bet you guys have some, if not all, symptoms. That rear cylinder was burning rich from day one, with the choke stuck on. He did notice a slight bog too, which is gone now, and the throttle response is a lot better.

 

Bought my 650 in march of 2004,first ride out of parking lot bike stumbles. Took to dealer say float level to high. Bike has been doing it since.[ STILL NOT FIXED] I think it has something to do with level sensor in the rear.

 

Mine only did it RIGHT after my first oil change and hasn't done it since, it has been suggested that if the crankcase is overfilled (still in the proper range on the dipstick, but on the high side) the oil can get into the intake and sufficate the engine. I never drained any off and it hasn't done it again, however I have not ridden on similar terrain since. I would see where your oil level is and go from there, others have done this and it has solved the problem...Good luck!

 

Just changed oil about 100 miles ago.I have the proper oil level.Buddies I ride with have not had this problem.We rode the sand dunes this last weekend,over studder bumps and berms.Thats when the problem starts.I think that articcat does not have a fix for any of their problems! I inspected the check valve,found nothing also.Had it at the dealer,they had it for 3 weeks or so.They could not duplicate.Does anyone know if the level sensor can be bypassed?

 

I have read about bypassing the check valve behind the tail light, I think it's even referenced in this thread somewhere...that also has fixed some peoples problems

 

my 650 has never stalled out before since i bought it, but what hellonewman said about the oil level being on the high side makes sense. after doing an oil change, i was out riding and noticed oil dripping down onto the skidplate then onto the ground. i traced it to the that "duckbill valve" on the bottom of the airbox. turns out when there is too much oil(even if it is still in the range on the dipstick) it comes up into the air box and might clog the carbs. all u need to do is drain out some of the oil. When i was at the dealer purchasing it, he told me not to thread the dipstick in all the way when checking, but the manual says to thread it in. i guess when its threaded all the way in, it pressurizes the crankcase and forces some of the oil up which gives a false reading on the stick. shouldve listened to the dealer.

 

Not only is it not possible to pressurize the crankcase (it's vented to the atmosphere) but if it was pressurised it would be from the pistons coming down. The difference between the fill cap unthreaded and down tight couldn't be measured with a 1 psi gauge or change the oil level enough to see. The oil getting thrown around the engine by moving parts and will find it's way into the vent and the air flow in the air box will pull it up the hose into the box. It will be worse if the crankcase is over full.

 

your totally right about that, i completely forgot about the venting. I guess it was just one of those times when someone just says something and u dont think twice about it.