Hopefully some of the experts here can help me out. I've had this Arctic Cat for 1 year now and have been having a recurring problem. I've only had it out riding for an extended period (about 3 hours or more) a few times. On each of these occaisions the same thing happened. After about 2 hours the spark plug slowly starts to act like it is fouling out and within 10 or 15 min. it has lost most of its power and can only limp along in first gear. It idles fine and revs up fine. The only thing that helps is to put the choke on, this will let you get into 2nd or 3rd gear but thats it. I've swapped spark plugs, cleaned the air filter, and made sure the fuel tank hose isn't pinched. It will run fine tomorrow.

Thanks!

 

If it runs better with the choke on then for some reason it's not getting enough fuel. Start at the tank outlet & check for blockage, dirt,ice,water etc, then check needle& seat for dirt or obstruction. Check vent hose fron filler cap, can you blow thru it?

 

Vent tube from cap gets my vote. Happened to me. Gets twisted from opening or closing.[img]i/expressions/face-icon-small-happy.gif[/img]

 

If it is the vent tube then it will run fine at slow speeds and cut out at high speeds because the tank cannot equalize the pressure. A kinked vent cap tube acts like it is out of gas. He said that it is acting like a fouled plug. There could be several things going wrong.
If it runs fine for a certain period of time and then cuts out. I would suspect heat could be the culprit. You may be overheating your motor. Check and make sure the temp light works. Change your oil and oil filter. On an Air/oil cooled machine it is vital to keep your oil and filter changed every few hours of riding.
You need to notice the terrain that you are in when it cuts out. If you have debris in the fuel/carb. then when you are bouncing around it may cause peices of debris to lodge itself in the jets, or float bowl. Since you have had it a year make sure that the fuel is fresh. I would also spen $2.00 and buy an in-line filter. this will tell you if you have debris in the fuel. But if it idles and revs fine. The loss of power tells me its your cylinder and piston and it needs a re-build. When your engine is cold the piston/sleeve fit is tight. When the motor warms up the metal expands and the piston/sleeve fit becomes loose which will cause you to loose power. You didn't mention anything about smoke though and if it was this there should be a lot of Blue smoke!!
Lastly, it could be an electrical problem. Check all your wires and connections. If anything or frayed or corroded then clean and fix them.
We really need more information to better decide what is wrong with your machine.

 

Thanks for the replys!

Its not the vent tube, I have checked that. The fuel is fresh and the air filter and oil are clean. Thankfully there is also no noticeable smoke. I will get an inline fuel filter.

I haven't had a chance to look at it all week until today. In the past when this has happened it took a few hours of riding to notice any problems. Today with the engine cold the same thing happened at start-up. It acts like the plug is fouling out. With the choke on it improves a little.

I have been told it may be the fuel pump or ignition coil. What do you think and is there anyway to test these to see if they are going bad?

The needle and seat are nice and clean. I have checked all wiring and everything looks fine on the outside.

Thanks

 

There is no fuel pump so we can rule that out. The next time it does this try turning the lights on and see if it makes a difference. I've had a coil in a truck act like this but not a quad. If you have a multimeter check the battery voltage with engine off, then engine running at idle, and about half throttle. I'm thinking it could be the rectifier, but try the light test and let me know what the voltage readings are. Since you said the needle and seat are clean I take it that you have had the fuel bowl off and it is clean too.

 

Before changing any parts, try simply adjusting your valves.

 

Having the lights on did not make any difference.

I checked the voltage and it remained constant at about 13.5 volts with the engine off, at idle, and at half throttle.

Can you tell me what the valve clearnance is for a 2001 AC 300?

Thanks

 

The voltage is ok. The valve clearance should be on a sticker on the frame, probably viewable from the rear under the tail light. I have it for the 02 300 and it should be the same.

intake: 0.03-0.08 mm
(0.001-0.003 in)

exhaust: 0.17-0.22 mm
(0.007-0.009 in)
This is for a cold engine, the engine should be TDC on the compression stroke. There is a timing inspection plug on the engine case shifter side of engine about 10 oclock position when viewed from the side. It is a 17mm bolt right beside the cyllinder. If you need more info let me know.

 

The king quad has a fuel pump so shouldn't the ac300? The suzuki engine is tilted so the carb is higher than gas outlet for the tank.