600 RMK Airbox backfire???

VeRt 600 · Dec 5, 2008

Hey guys I have an issue tuning my 04 600 RMK from 4000 rpm to idle. I have been trying to tune this thing for a bit. When I let off from half throttle the rpms come down nice till about 4000 and then it will drop quickly to 1500 rpm and let off a quite pop through the airbox. I am not sure if its too rich or lean on the idle circuit. The plugs are a darker tan color. Also the PERC doesn't seem to engage unless I rev the machine to like 3000 then press the button or it will stall. The setup right now is:
Mains 420
Needle #4
Pilot jet #30
Air screw 1.25 out
Fuel screw 1.5 out
Altitude is flat land anywhere from 500 to 2000 ft

It also has:
Slp high flow airbox, two florites in dash, VF3's and slp can. The belt tension is just about right. I am kinda looking for some advice or pointed in the right direction with a proper jetting setup to avoid chasing this for longer than I want. Any info appreciated. Thanks in advance.

flatlanderfornow · Dec 6, 2008

Carbs clean? Good gas? Did someone mess with the TPS? My 04 Switchback
liked to have Premium fuel and run in the premium position on the key switch- went into reverse better. On the fuel screw I let mine idle and adjusted it until the idle
speed would remain steady for as long as it idles and doesn't load up. I think they were
about 3/4 turn out or so. Air screw sounds about right. Check carb synchronization
as well. All I can think of at this late hour- good luck

VeRt 600 · Dec 6, 2008

The carbs are clean, synced up and I have been running 91 since new. I think it might be pilots to lean I think. I might try a to bump up the pilot to a #35. I just added the flowrites in the dash and haven't touched the jetting yet. Did anyone else have to jet up after they put in two flo-rites????

MARV1 · Dec 6, 2008

When I had my '04 600RMK I ran:
410 mains
Needles #2 from top
40 pilots(run these still on my '07/08's)
fuel screw was at 1 or 1.25 out
air screw at 1.25
And a Tempaflow and got 12-15mpg all the time riding anywhere from -35 to 40*F. You need to jet down to 400's or less depending on your temps. Removing the airbox shelf enrichens your mixture, opposite of what SLP recommends so jet down. You'll be surprised in the difference, bet it is kinda doggy now being so rich in the midrange.

VeRt 600 · Dec 7, 2008

What kinda altitude you running at Marv?? Are you a flat lander? I am running anywhere from 600 to 2000 ft. The temps I run at are anywhere -25 to 0 C. I will have to try your setup to see what I get. I know its running lean on the idle right now after some testing this weekend. Thanks for the reply. Any other guys have any input on a good setup for my altitude??? Thanks

MARV1 · Dec 7, 2008

I run from sea level to 3k feet, 40 pilots flat out work great for me in the 600VES and 600HO's I've had before and own now. Also ran 62g weights in the '04 I had, always was able to pull them in any condition.

Sundance Kid · Dec 8, 2008

If its backfiring its lean.
07/08 RMK's came with 50 pilots & 0.6 air jets from the factory. At our altitude, 4000-7000 ft, they are too lean for easy starting. I'm bumping mine up to a 55 pilot and changing the air jet from 0.6 to 0.9. Makes a ton of difference on the ability to start on the first pull. I'm tired of pulling 5-6 times on a warm machine to get it started.
Other than the starting issue, 50 pilots have been good for our 07 & 08 600 RMK's

Sundance Kid · Dec 10, 2008

Here's the Polaris part numbers for needles, air jets, etc.
It's always easier to do the dealers job for them when you have the right tools!!!
If its too small to read the part numbers, PM me & I'll E-mail it to you.

Rob1334 · Dec 10, 2008

PM sent, cant quite make out all the numbers, bob1334@hotmail.com

Thanks!

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600 RMK Airbox backfire???

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