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?

 

I have an Artic Cat 2003 400 4x4 FIS and recently went over my carb. My setting was 2 1/8 turns out and I could get at it with the carb on although it is much easier with it off. If it is running ok where it is, you should be fine.

 

Weekend Warrior, I have an 08 AC 650 wwith the same head on the adjustment screw. Where and how can I get that tool?

 

I am familiar with the screw typw you mentioned. I needed one for some work on a friends machine a while back. What we did was take a small phillips screw driver that was the propper diameter and cut off the phillips head with a dremmel tool.

Then we placed it into a vise and ran a flat file over one side of the round stub to kind of make a "D" like shape. It was not an exact fit but worked enough to get the job done.

Also, if you have a short enough screw driver and small enough hands you can make the adjustments with the carb in place and maybe having to remove the side panels and seat.

If the adjustment screw is a phippips head you can buy for a few $ a screw driver bent into a "L" shape with a phillips head. In fact I think there is one in the tool kit with the machine.

SJ

 

so, it's running now.. and not cutting out at 3/4 throttle, and not back firing?

pull the spark plug and see what it looks like...

2.125 to 2.75 is generally the majic number ..

remember, you aren't getting to the main jets till 80% throttle, and all the majic is in the needle...

your basic fuel mixture REQUIREMENT hasn't changed at that first 20-30% of throttle