I am new to the forum and have an ongoing problem with a 2003 Polaris 600 Sportsman that will run fine for awhile and then start running on the left cylinder with a metallic ticking noise on the right side. If I rev it up the engine will clear up and run okay again until it starts doing it again (time frame varies). The needle and seat were leaking since I got the machine and after I replaced them, it ran like new for about 200 miles. Yesterday, it started the one cylinder thing again. I don't know if this could be fuel related or why it stopped for so long after the needle/seat change. I wondered if it could be a lifter leaking down and making the right cylinder cut out, along with the mechanical noise. Any help would be much appreciated.

 

When it does it's thing, do a compression test.

 

Thanks Doctorturbo. That would make sense to show whether it is a lifter/valve train problem. I'll have to try and get a compression tester. The trick would be to catch it while it's in the middle of an episode. When you shut it off for awhile, it will usually start up running okay and takes some time before it begins to breaking down again. The fact it ran so long after the needle and seat replacement makes me wonder if it could be fuel related, but I'm not sure what kind of problem taking the carb off and apart could have temporarily fixed.

 

Could be many things, that's why it is so hard to track down.
Let us know what you find out so we all can learn.

 

My 700 did that when I first bought it and would go through water, bad spark plug wire, it would start shorting out to the frame making a spark/ticking noise and backfire. new spark plug wires took care of it.

 

He's right. Check your plug wires.

 

Plug wires seem okay. I'm still checking carburetion. I took my carb apart again and everything looked fine since the new needle and seat. It ran great for about six passes down a field after I put it back together and then started the one cylinder thing again. I noticed it was throwing a few small drips of gas out of the front outlet area of the carb (no drain hose) when you rev it. I also noticed the rubber hose/boot from the air box to the carb was weather cracked through in a couple of places. I thought I read somewhere that air leaks before the carb can cause running problems. I wonder if it could cause the over fueling, as I know the needle/seat is good. It won't seem to rev up at all without the top on the air box, so too much air must affect something. I've got a new boot/hose on order. Any thoughts.

 

It should run funny without the airbox lid on, you are correct too much air. The cracked boots is a good place to start but that will make it run lean not rich. So your compression checks show both cylinders the same? You could also do a leak down test, I have never done one, but its basically getting the pressure up in the cylinder and waiting to see how long it takes to blead down, dealers can do that. Its only one carb so if its always the same cylinder that seems to be cutting out I think you can eliminate the carb.