Arctic Cat 400 Pilot Screw Adjustment Help

[AC400TX]

I prefer to do as much myself as possible, but I was uncomfortable removing the carb, so I decided to have a local shop install my Dynojet kit on my 08 AC 400.

The guy doing the install told me he didn't adjust the pilot screw (aka fuel mixture screw) because it required a special tool he didn't have.

He described it as round on one side and flat on the other. The Dynojet instructions say to adjust with a flat head screwdriver.

I called their tech line, and they seemed to think only Honda and Polaris used the D-shaped adjustment screw, but they're sending me a tool anyway.

Per my manual, the stock pilot screw setting is 1 3/4 turns out, and the Dynojet kit recommends 2 1/2 turns out.

If it's idling and running okay at lower throttle, will I be okay leaving the pilot screw at the factory setting, or should I go ahead and adjust to Dynojet recommendations?

Can I make the adjustment with the carb still on, or does it need to come off?

Edited December 16, 2008 by AC400TX

[Ajmboy]

I would go with the Dynojet recommendations for that engine. As long as you can access the adjustment screw, you should be able to do it with the carb on.

You are right, the instructions tell you to use a flat head: http://www.dynojet.com/pdf/Q623.pdf

[Raptor8]

I agree with AJMBOY: I don't know much about ACs, but if you are piped then go with what Dynojet says- they do it for a living. Plus they have an 800 number you can call which helps a lot.

Edited December 16, 2008 by Raptor8
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