trying to sync carbs

[OLY-XSer]

so I started to sync my carbs and didn't get far. i made a carb sync tool useing vinyl tubing and 2-stroke oil. Everything is conected together with Y's and T's with about 7 foot of tubing for each carb. when I started up the bike, it was pulling the oil in 1 and 2 so hard I had to kill the bike immediately so not to suck oil into the engine. Im guessing that the carb sides are way out of sync. I have to let the oil drain back down the tubing over nite anyway. I turned the middle adjustment clockwise a bit. It made the idle go up. So I turned the idle down and played with the middle adjustment a little. I am going to try to hook up the sync tool again after it drains. Question is when I turn the middle adjustment clockwise, is that starting to balance the sides? Im just trying to get it so I can hook up the sync tool without pulling oil in the engine. there is only about a foot of oil in each line in the bottom of the tubing. Maybe i need to take out a little oil also. What do you guys think?

[DGXSER]

If anything, you need more oil more weight to pull. But I think what you really need is some sort of orifice or valve to limit how hard it pulls.

As to the screws, here is the secret to them. None of them adjust no 3 carb, that is basically the starting point. The screw between no 3 and no 4 synchronizes those two carbs to each other. The screw between carbs 1 and 2 sunchronizes those two to each other. Then the screw between 2 and 3 adjust 1 and 2 as goup, so you can bring both pairs together.

So start with 3 and 4, move to 1 and 2, then bring both pairs together.

[planedick]

Long tubes

If you're gonna use oil you need really long tubes way high in the rafters to keep from sucking the oil into the engine. Water is heavier than oil, but better yet get a proper synch tool. It is WWAAAAYYY less expensive than a blown engine from running way out of synch.

[clcorbin]

but better yet get a proper synch tool.

Heck, can you still GET a PROPER sync tool (aka: mercury!)??? I am NOT happy with my glycol based carb stick. It has a LOT more problems than the old school mercury sticks.

[clcorbin]

Oh, and if your carbs are way out, a quick bench sync will do WONDERS for the speed of the sync.

Just take the carbs off and then adjust them until they all have the same throttle plate gap. You can actually get it pretty close by eye-balling it, or you can use a very thin wire feeler gauge.

I used the wire from a twist tie to bench sync my carbs this afternoon. When I fired the bike up, all four cylinders where within 3/4" from each other and they dialed in very quickly.

[natemoen]

Morgan carbtune. Way easier and safer than anything else.

[planedick]

Morgan

Morgan is better than mercury and can be transported without leaking anything out and smaller too......

[OLY-XSer]

im going to try pre-syncing. then go to my homemade sync tool..

[DGXSER]

If you alreayd own a Mity Vac or somethign with a vacuum gage on it, THIS setup is pretty inexpensive and handy.

I use it but without the four way valve, I just move the vacuum line nipple to nipple on the carbs and adjust. If I read 9.25 on one, and 11.25 on the other, I leave one hooked up and adjust to 10.25, then recheck the other. Goes pretty well and not to terribly tough to do. Easier wiht all four reading at once, but those Carbtune things are a liitle pricey for the cheapazz crowd, of which I am the designatled leader of the pack!!

[crazy steve]

If you alreayd own a Mity Vac or somethign with a vacuum gage on it, THIS setup is pretty inexpensive and handy.

Yep, that's what I intend to build when I get to mine. One other thing you can do to dampen 'gauge flutter' is install a restriction in one of the brass fittings. A old carb jet, or even just solder it closed then drill a small hole.

[petejw]

fwiw,

ive tried using one of those 4 - 1 valves, u need to be careful
with them as the one i used doesnt fully close off and
picks up vaccuum from the other cylinders, in the end i
used 4 individual aquarium valves with 4 good lengths of vac
tubing with a single vac guage, the plenum isnt necessary as
the valves dampen the pulses enuff for a good reading.