black spark plugs?

[snow_dog]

Sled is a bone stock 01 XC600, except for a Goodwin clutch kit this season. 5000 miles.

Had trouble with a cold start the other day so I pulled the 300 mile spark plugs to
find them black and oily. I know they should be a tannish color so something isn't right.

The other thing I noticed is that it tends to studder or stumble after idling for more than a minute, like it's loading up. Never did that before. Otherwise it runs strong.

Need some ideas what to look for here.
Keep in mind no adjustments from factory settings have ever been made, original jets ect...

I'll double check the oil pump arm setting but I can't imagine that would have changed.
I've been using Sea and Snow oil for the past few years if that means anything.

Maybe time to go through the carbs again?

 

[jimfsr]

The plugs will turn black if the sled idles when cold, as it is usually pretty hard to atomize fuel in a cold engine. Could also be the jetting is a bit rich at idle, try leaning the fuel or air screws slightly, depending on which type your carbs have. Probably nothing to with oil pump. Run the sled to operating temp. then do a wot run for a 1/8 mile or so, check the color then, it should be cardboard brown. Prolonged idling like when waiting to load the sled on a trailer, can cause the plugs to soak, and the next time you try to start it they foul out. Lastly, the inlet needle and seats are prone to leak in some Polaris models, and the leaked fuel will settle in the bottom of the crankcase, and be very rich at startup. Try shutting the fuel off when trailering. Just dont forget to turn it back on. You could make it a half mile before it runs out. I have seen guys tow it to the dealer, only to have him turn on the fuel, pull her a few times and all is well.

 

[snow_dog]

Yeah I started it cold, and feel now I let it idle too soon with no choke.
It started fading and when I tried to rev it up it backfired and died. It wouldn't
even pop when I pulled it so that's when I pulled the plugs.

I do shut the fuel off whenever trailering, and yes I've forgotten to turn it back on lol.

I'll get some new plugs and try the wot run to see what they look like.