So I was trying to synch my carbs with a home made manometer, and I got some air bubbles in my manometer. Without realizing it, I still tried synching my carbs and now they are all out of wack. Once I got the air bubble out, I tried again. Now when I start my bike, the number 3 and number 4 carbs want to suck the oil up, so I just turn it off immediately. I have been trying to tune it by ear but I still just cannot get it right. The throttle wants to hang for a while once I rev it a little bit.

Am I just screwed until I get a gauge reading manometer, or is there some way I can still get a decent reading without sucking up any fluids? Is there any sort of stock positioning for the screws? I could not find the relationship that each screw had with the ports, I was completely dumb founded. Is there some sort of general rule that happens when, say you tighten the screw in between port 1 and 2? Or does that dynamically change across all the vacuum ports? I am lost, any info is much appreciated.

Thanks

 

Ok, so after a while of internetting I found that the number 2 port is constant. There is no changing it. This means that the screw in between port 1 and 2 only adjusts the #1 vacuum port. The screw in between 2 and 3 only adjusts #3 vacuum port, and the screw between 3 and 4 only adjusts the #4 vacuum port. Now with this knowledge, I think I could get it close enough to be able to use my manometer again. All I need to know is-

What affect does loosening or tightening the screws have on the vacuum pressure? If I loosen, does it decrease the pressure or increase?

 

The screws in between the carbs adjusts the butterfly plates inside the carb inlet. The adjustment is used to get all four throats to flow the same amount so that carb response is smooth and linear. Tightening the screws would open the butterfly more. The screws are spring loaded so you cannot press hard on them while adjusting. You need to adjust one and then let the idle settle. Normally you are using a gauge to do this. If you are pulling fluid from the gauge, it would seem that you have opened up one or more throats too much in relation to your baseline (#2). You will need to close them down. You may check (while not running) by lifting the slide and checking the opening of the butterflies down in the throats. They should all be about the same position.

 

Thanks for the help. That is exactly what I was wondering- but just to clarify. If my carb #3 and #4 are sucking fluid, that means I need to loosen the screw in between carbs 2 and 3 and the screw in between carbs 3 and 4 to lessen the vacuum pressure?

I will get back to this tonight. Again, thanks very much for the help.

 

Ok, being able to physically look at the butterflies helped tremendously. I took my carbs off, and with a flashlight underneath, adjusted my synch screws so that each cylinder had a tiny, tiny crescent of light coming through. Now I see why people say to synch 1 and 2, then 3 and 4, then 2 and 3. And I also see now why changing one affects them all. Since its getting late, I had to stop trying to tune and I am now left with a couple questions:

1) When you look at the butterflies, should each end of the butterfly open up a tiny bit? I didn't even move the sliders, I was just able to see the one side with the sliders in normal position, but now that I think about it, I didn't see if both ends of the butterfly were opening.

2) When I put my carbs back on, they seemed much better than before, but they wanted to hang pretty badly when I would rev. Any idea how the carb synch process could cause this? Is it a matter of all the carbs being either open or closed too much?

3) While I am adjusting, my airbox is completely off- will this throw off my readings?

Again, thanks so much. I would be completely lost without all the help from this site.

 

1) the butterfly is a one piece of metal. one edge moves the other moves too.
2) Open too much. fuel is being pulled from the main jet and too much air is going past the butterflies.
3) I have adjusted mine without the airbox and only had to use the manual idle adjust **** to raise my idle a little when everything was back together.