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-   -   sync carbs. (http://www.slednutz.com/showthread.php?t=2553)

Madcow 12-16-2008 09:27 AM

sync carbs.
 
I use this method as a quick sync, no special tools required and works just fine for trail sleds. plus you dont have the sled running during any of the adjustments smoking up the garage.

with a warm engine adjust idle screws to get the idle where you want it. shut engine down and remove air box. find a drill bit that just fits between the slide and carb body without touching the throttle. since all 3 will be a little different you will find a drill bit that is about average of the 3, the use that to set all 3 idles to the same spot.

now with a 10 mm wrench loosen the lock nut on top of the carbs where the throttle cable screws into the cap. with the throttle held wide open or zip tied wide open make sure that the bottom of the slide goes high enough to clear the opening of the carb. do that on all cylinders.

release the throttle, i stand on the right side of the machine(left and right as you sit on the machine), so on the machines right side facing the seat, with my left hand i control the throttle lever, with my right index finger touching the slide and my pinky touching the slide of the pto carb i slowly sqweeze the gas, what i am feeling for is that both carbs move at the same time. but, the center carb is the one i leave alone, so if the pto carb is opening before the center carb screw the adjusting bolt on the cap into the cap a little.
with them two in sync, I then move my pinky to the center carb and index finger to the mag side carb and do it over again, if the mag side is opening later than the other two you screw the bolt out of the cap until its synced,


once they are all synced, then check the amount of play at the throttle. like brian said you can use a credit card and slip in between the lever and block, then tighten bolts in the cap until the slide just starts to move.

double check that the carbs are in sync, turn the steering hard left and hard right to make sure that the slides dont move up at all. put the air box back on. start the sled, turn the steering again making sure the sled doesnt rev up when you steer, double check idle speed and you are good to go.

bigthunder12 12-16-2008 07:04 PM

Thanks guys. I'll be doing this tonight and let you know what happens.

Polaris1man 12-16-2008 07:56 PM

Preacher man with a new testament,again!!! Truthfully though, I believe the manual for twins says a 5/16's or 5/32's drill bit is what I use to sync them in, that is the damn piece of shit Keihn carbs!!

PolarisRich 12-16-2008 09:13 PM

Wow, thats the exact same way that I do it!
Nice "How To" Madcow.

Madcow 12-17-2008 01:46 PM

ha, never even looked at the size of drill, just grab one that seems to fit whatever sled i am on. thats funny.

Rubi 12-26-2008 11:32 PM

With the throttle wide open, the slide is flush with the top on the airbox side, but on the motor side the slide hangs down into the bore about 1/8 of an inch. Is this wide open, or do I need to raise the slide higher so that it is flush on the motor side of the carb?

Madcow 12-27-2008 04:06 PM

if you can get it flush on the inside.

Rubi 12-27-2008 04:32 PM

I set it with the slide flush with the top on the motor side of the carb. It idled high enough to engage the clutch. When I set it flush on the airbox side, usually I'm a lot closer.

Madcow 12-28-2008 01:31 PM

thats why i say if you can. ha. some machines there is enough throttle length to do it.

FrankieJames7 12-27-2014 07:36 AM

bump for good thread

Dirty_Harry 12-31-2014 01:01 PM

I am going to sticky this one.

mmgg 01-06-2015 03:55 PM

That works great but if you want them truly sync'd you want too finish with a balance for best performance. tube and mercury or bottle method like the shop does.
https://www.youtube.com/watch?v=Y_WDF6glD5k


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