Polaris 90/K@N Filter jetting
 

I replaced the airbox with a K@N filter plus the new jet, now it idles fine but sputters on acceleration. Does the needle also need to be adjusted? Anyone know or have any suggestions? Anyone make the same changes and not have any problems?

Polaris 90/K@N Filter jetting
 

Yes the needle needs to be adjusted. Move the clip down, moves tapered end away from the seat. Test it until you get it running right at about half throttle (needle), THEN move on to the main at full throttle.

RICH or LEAN:

Lean: If you can partially cover your new air filter and the quad runs better, you are lean.

Rich: Turn off the gas. If the quad runs better as the carb runs out of fuel, you are rich.



Better a little rich than a little lean. Lean is mean!

Polaris 90/K@N Filter jetting
 

The main jet size required will vary dependant on exhaust type. 120 to a 110. Altitude will also effect this finicky set up.