I think that is opposed to the concept of sync. There needs to be a balance relative to each other.

Sorry you're having such a frustrating time. I can't say it was easy when I did it, but it did work.

Do you have all four tubes connected at the same time? You mentioned it being all out of whack above 1200 rpm, but this is the recommended level for syncing, so why not go with it?

 

It doesn't matter if the lines are separate or linked. The weight of the fluid helps the fluid in the lines from being sucked out. The volume of each line has to weigh more than the vacuum the carb generates. A larger volume of fluid will help. Keeping the rpms down is also necessary when synching.

Think of siphoning gas out of a tank with a small hose. Filling the little hose is easy. Sucking out the hole tank takes lots of effort. Same principal for the gauge.

 

The bike does run smoother after the 1200 RPM"sync" what is the point of a sync if they are only in sync at 1200 RPM? shouldn't this be even throughout the range?
I still have an annoying miss around 1200-4500 RPM.running the bike at even throttle trying to maintain an even rpm or low speed ie going through parking lot. or 20 or 30.if I edge up on the throttle but at a flat speed the miss goes away.at idle rather than hearing just an even pop pop pop i hear pop pop pop gurlge pop. I do have jetted carbs and a D&D slip on. I did adjust it once by hand to hear an even pop pop pop but the carbs showed to be way out of sync.

The reason I ask about the separate lines is when I adjust one carb it affects the level in the other three tubes. it seems if they each had their own reservoir I could sync using the vacuum of each independently but of course in reference to one another so tube 1-4 all separate but each tube with X CCs of oil the amount of oil rise x the amount if vacuum. This is the way the pro tools are? And if they were in sync then x amount of vacuum should rise evenly throughout the RPM range? So thats my hypothesis.
But we all know those are educated guesses. I understand the tubes connected at the bottom in this theory would show relative vacuum against each other but I am sick of 30 tries to get this right I eventiually will mess up and drop my tank and dent it, not to mention I live in upper end apts and the neighbors are going to get sick of Pats garage and lube center. otherwise I will move to the low rent apts where the cars are up on blocks and everyone has speakers for sell.

 

nice job

 

Haynes manual says to do it at idle and idle should be 1200 rpm +/- 100, so I think you're doing it right.

The slow speed miss you're referring to sound more like a fuel adjustment. You might open your pilot screw a 1/4 turn to see if it improves. Had the same thing and opening the pilot screw a bit helped a lot.

 

Synching the carbs is like 4 guys pulling on a rope. If one guys pulls too hard it can affect the other 3. You can set the carbs on a bench by eye or with feeler gauges and be pretty close to the mark. The individual screws are to deal with variations from cylinder to cylinder. Valve lash, rings, carbs all have minute differences that can be compensated for with the adj screws.

The pilot adj will help the 1200 rpm area. Check out the link about pilot jets.

http://www.factorypro.com/tech_tunin...%20cruise.html

Has any one checked up on gasoline lately. I wonder if trying some race gas would clean up this area? Lots of things are added to our gas these days. Oxygenators, alcohol. It seems like lots of people, myself included, are experiencing low rpm, cruising throttle issues on bikes that previously ran pretty well. I know from experience that these chemicals affect carb parts on vintage cars I have worked on.

 

I try to stick with Shell V power 93 $2.90 a gallon, but cheaper than a fried bike.
Well I just got my china fairings in so I will adjust fuel screw when I am pulling the old fairings off.
see thread on china fairings.

 

The main reason for the professional tools using mercury in the tools and the cylinders not being connected is to be able to set base vacuum. Since our bike does not have a base vacuum adjustment and carbs 1, 3 & 4 are salved to 2 (wich is not adjustable, might have the numbers backwards but u get the point) being to show inches mercury of vacuum is irrelevant. All you need to see is that all four carbs are pulling the same vacuum. This means all your tubes must hold equal cc of fluid when the engine is off and the levels are even (ie not having one tube with a bend and another without). Use all 4 at the same time to get the best resolution and save the most time in tuning. It will still take round about an hour once you have the engine running with the setup attached to get it right the first time (or at least it took me that long) to figure how much to adj 1 before it changes the bal to 2,3,4 and so on. My tool uses two 90* elbows (one at each end) and two 3-way T fittings (the middle two) with apx 1" long pieces of vac tubing connecting the fittings flat across the bottom to keep the vertical run perfectly even between all the tubes.

I have seen people say u can bal 2 cyl at a time, this would only be good if u had a professional manometer that read in inches mercury with only two guages. If you are making your own rig there is no reason not to balance all 4 at the same time. the length of the vacuum tubing from the rig to the engine is not critical as long as there is not a major difference, the difference is with the weight of the fluid in each tube compared to the others.

(basic example of my rig)

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Hi all,

Would motor oil work for this setup or would the thicker ATF work better and not get sloshed around as much?

 

thats what I'm guessing. mine worked better with the ATF then motor oil I'm using 5w-20 right now. but idk if thats just because num 1. was changed. I'm going to have to eyeball it. maybe they have a thicker fluid in it or something. mY guess is that they all have to be relative to each other or one sucks something it or its just pulling to much for the connectors....watevs