Carb Adjustment help

[captjanes]

i took my carbs off for cleaning and i seen that the air screw was all screwed up one was at 1 turn open another 2 turns and another 1.5 turns and one 3 turns.. i was wondering what is the correct setting for that screw? i usually go with a turn and a half (1.5) on my ski-doos and atvs but this is a 4stoke so im not sure if it is different.

[skids]

First off, this pilot screw is an enrichening screw to compensate for those bitty holes in the tops of the carb throat. i.e. Screwing them colockwise slows the rate of fuel. This is mainly for idle range rpms before the main jet needles really take over. I wouldn't adjust those unless your spark plugs are showing the need and I do that at about 1500 rpms to keep the battery from draining down. I also wouldn't adjust them unless you have done a vacuum synch at 1500 rpms because that will have an affect on richness if vacuum adjustment is significant. Of course all bets are off if your carbs need cleaning.

[skids]

P.S. 1.5 is a good starting point if everything is stock and maybe a bit more is needed for the 80 model.

[BA80]

i took my carbs off for cleaning and i seen that the air screw was all screwed up one was at 1 turn open another 2 turns and another 1.5 turns and one 3 turns.. i was wondering what is the correct setting for that screw? i usually go with a turn and a half (1.5) on my ski-doos and atvs but this is a 4stoke so im not sure if it is different.

What skids says is right about the mixture screws being mainly for closed throttle/idle fuel flow. Properly adjusted they will usually differ from carb to carb because except in a pefect world, all carbs will be a little different and all cylinders will have slightly different requirements.

1 1/2 - 2 turns is a good place to start but will require individual adjustment to dial each one in. I use my guages on my sync tool to do that. A bit complicated to begin with but really quite simple once you learn the proceedure.

[Courtney]

First off, this pilot screw is an enrichening screw to compensate for those bitty holes in the tops of the carb throat. i.e. Screwing them colockwise slows the rate of fuel. This is mainly for idle range rpms before the main jet needles really take over. I wouldn't adjust those unless your spark plugs are showing the need and I do that at about 1500 rpms to keep the battery from draining down. I also wouldn't adjust them unless you have done a vacuum synch at 1500 rpms because that will have an affect on richness if vacuum adjustment is significant. Of course all bets are off if your carbs need cleaning.

So Skids, totally rebuilt my carbs; what is a good starting point to put the mixture screws at for starters? I synched the carbs via setting the butterflies half way over the 2nd hole in the throats as per the suggestion on this site.

[skids]

If your idle isn't too high with that method, you can try and adjust the idle screws at 1.5 to 2 turns. You may need to repeat the process if you didn't use mercury manometers or gages. Your vacuum created by the engine may not be equal from cyl to cyl.

[mack]

As many

have said 1.5 -2 turns for the idle mixute screw is a starting point after the carbs have been bench sync'd. The bike will start right up and a modest idle screw adjustment to keep it running at 1050-1100 rpm. A guage or vacum sync should be next, to adjust individual carbs to your valves. It will smooth out at this point. Re-adjust your idle back down to 1050-1100 range the ride it for a bit with tach in all ranges, 100 miles or so. Then take a look at your plugs and adjust the idle mixture screws accordingly. then re-sync. Next.... ride the crap out of it.

[skids]

I agree. If you got it running half-ways descent, ride it. You might even consider using some fuel system cleaner while you do that, like Techron or Seafoam.a Take an extra plug and a wrench just in case.