1997 Polaris Jetting prob, it fouls the plugs

[sledman411]

I have a 1997 polaris 600 XC tripple with bout 5000 miles on it, it likes to foul the plug after 10 miles or so, and i just pulled the carbs and looked at my jet, i have a 270 main, and a 35? piolet jet, im wondering if i sould go down or what, the needles are set to there lowest position also, any help would be great, thanks

 

[jimfsr]

If the needles are set at the lowest position and it runs rich, you can drop the pilots a little. You will have to do some testing to determine the best clip position. Set airscrews at 1 1/2 to start. Does it foul only one plug? Always the same one? The jetting on the carbs may be different from one end to the other, as the middle cyl. tends to run hotter, so usually a little richer. If it is the right cylinder every time, check the fuel pump pulse line, the diaphram could be leaking fuel into the crankcase and causing it to be rich.
Also check the commpression on all three, should be +-10% between them and not less than 100psi. You could have a low cyl. not burning the fuel completly, fouling the plug.

 

[sledman411]

It fouls all the plugs, but the main jets sound right? I thought that the guy before me may have jetted it for preform pipes and then left the jetting and took the pipes when he sold it, i dont know when u say drop the pilots, to what 32.5, or what?

 

[jimfsr]

You have the stock jets. My guess is the previous owner was trying to fix the fouling problem by leaning the midrange (dropping the needles). The polaris triples were notorious for being fussy to jet, and the piston port design, which worked great on the 488 twin, was not good on a triple. The plug fouling problem is common. I dont have any jetting numbers to fix it, you may have to just play around with it and try some smaller pilots. You need to determine if it is a midrange rich condition(most likely). I have had some sucess with the U.F.O.'s from thunder products, but you have to be willing to play with it to get it right. I dont know if he will get back to you, but try to look up Doug Flannery, from gun lake Mi. He is a polaris tuner who was building engines that beat the factory teams in oval track all through the 90's. I will see if I can get his number for you.

 

[jimfsr]

Flannery's performance-269-792-0070

 

[rjsledworks]

How does the sled perform the first 10 miles and does it idle good? Check for restricted exhaust and air box, check compression, check that the chokes are set right and working properly.