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Discussion Starter #1
right now, when my sled is warmed up and i go to start, it needs a bit of throttle to get it going. also, after ive driven it and its hot, it wont idle down unless i use the choke. idles at 3 then when choke is pressed it idles down. does this mean i need to richen my airscrew?

ive gota 03 rev 600ho, with the mikuni flats, does turning the screw in or out richen it? does the screw control air flow, or fuel flow?

thanks
 

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Turning the air screw in richens it up, out leans.

The air screw is a needle and the more the taper is unscrewed from it's seat, the more air can be enter.

I would not try to richen it up yet. The reason it dies down when the choke is on is "most likely" because you flood it. OR "BOG" it down.

I only change pilot settings if there is a running problem at the lower RPM range where the pilot stage operates.

If your just "booting around" at near engagement RPM, BLIP the throttle a few times. If performance is good, there is no reason to adjust your pilot a/f ratio.

If you BLIP it and it bogs down and puffs a little dark smoke, your too rich.

If you Blip it and it hesitates and/or wont keep steady RPM, your too lean.


I suggest you first try to re-adjust idle. There should be a little screw that controls both carbs on the top. Try this first, it only takes 10 seconds.

You should only change your pilot settings based on performance, not idle.

Good luck.
 

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On my 2002 MXZ 700 I have to give my gas a quick flick (shot of gas)with my hand to get it to idle down below 2 after stopping.
 

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On the mikuni flat slides those are fuel screws not air screws.Turning them in leans it out and turning them out richens it.Check the factory settings on these then turn both screws in till lightly seated,then turn them out the recommended amount.For example my 800 twin is 1.5 turns out from being seated.Play around with these until you find a satisfactory setting.My twin takes about 20 seconds or so to idle down after driving it hard.
 

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Sorry dusteater, I assumed they were air screws since this is what was posted.

However if they are fuel screws, just do the opposite of what I posted. Turn them is for leaner, or for out for richer. as mentioned above.
 

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your best bet would be to leave it alone until you get at least 250 miles on it. if the problem persists take it to your dealer and let them fix it, more than likely it will work itself out.
 

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Discussion Starter #7
it wont idle down at all! a quick blip of the choke makes it idle down to 1800, from 3000. also, when starting it need some throttle to start otherwise it will start but idle real low then die. to lean?
 

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If the sled that you are talking about is a 2003 600 h.o, that would mean its under warranty . The dealer should be the person adjusting your carbs. If you mess around, lean it out, and fry the pistons, then you're not covered any more. Just an opinion
 

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Sound like a typhical characteristic of the doo series three engines. The pilots act rich when you go to start them but act lean at times when idleing. Just something I have learned to live with.
 

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I did a search and resurected this post. I have a 02' mxz8 with flatslides. My question is this: Is there a difference between the "fuel screws" and "pilot fuel screws". Also where are they located? Had some porting done by Kelsey, along with his piston kit and head. 0-1/8 throttle was WAY lean. Had size 15 pilots in, and now have gone to 20's. Kelsey mentioned turning the fuel screws to 1/2 out. This sled also has the new updated needles. So I guess I'm sheepishly asking if the fuel screws are the screws next to the pilots
 

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DUSTEATER !! You have a lean condition. Just back out your fuel screws 1 turn from where you are now. This is a simple problem and a simple fix. Your throttle response will greatly improve also. Have a nice christmas.
 
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