A question about jetting

[stmoxy]

I bought a pair of 1999 Polaris 400 Sports from a friend. He told me that he had them jetted at a Polaris dealer for the elevation where he ran them (7000 ft). He also said I would have to re-jet them for where I was going to run them. I took them to a Polaris dealer, as they told me it was fine and I did not need to re-jet them. I ran them once at my elevation (2000 ft) and they ran good but being a novice, I am not sure. Of course it cost money to see what the jets are set at. Am I getting taken for a ride or did he?

[Bruce!]

Welcome to the board!

[phdfishhead]

I know that rejetting in normally necessary when moving across elevations. This is what I'd do if I were you.

Go online to Babbits and look up the OEM main jet and idle jet for the carberator in your machine and compare it to what you have. This gives you a couple points of reference for where the jetting should be.

Install a new set of plugs, let it idle for awhile, and note any bogs or backfires and when they happen. Then check the color of your spark plug. White/grey = too lean, black/wet = rich, tan/reddish = good for the idle jet. If necessary, buy a few larger (richer) jets (aftermarket ~$3 each) and repeat the process. You should be able to identify the best idle jet for the bike at your elevation.

Repeat process while reving the motor at about 1/3-1/2 throttle. But adjustments this time will be with the big needle jet in carb. Move it a notch down to lean it, lift it up to richen it.

Repeat at 3/4- full throttle. Replace main jet down (smaller) as necessary until plug looks ideal.

Hope this helps