Synching carbs with a 4 way homemade manometer?

Ok... After much research and many different opinions I am wondering if I made a mistake dipping so much time and money into building this thing (It cost 35$ to make)


My KZ750 carbs are more than likely way out of sync. I didn't want to invest 100$ and I like to build stuff so I made my own manometer.

It's designed to link all 4 carbs together at the bottom. I read in a couple places it's better to do 2 at a time. It's also very basic with no restrictors or anything like such.

Is this system usable and if so how would I use it. When I was testing it out I found that when one goes up the others go down. As I can understand, all I need to do is adjust them until they are all measuring even and then lower the idle to factory spec and repeat. When you get synced carbs and a good idle you are good to go. I am not sure of the screw order though.

here is a pick of my manometer.

good for you...does it run better?...would be cool to try and use a real set to see how close this one worked...

dont listen to these guys opinions

i made my own helmet out of glue and newspaper and it works

I've seen a lot sites with instructions on how to build these. Never done it myself though. I don't think any of us are going to be able to tell you if your manometer is safe or will work. We didn't build it after all

My understanding when I was looking into this before is that the biggest danger is of sucking some of the fluid into the carbs. That would be bad. So don't do that.

I'd start with a bench sync. Take the carbs off and adjust them to get them as close to synced as you can. Some people will use a small wire or drill bit to do this. I found it easiest to look at the small pilot circuit outlet holes in the top of my carb body. In my CV carb there's a tiny little hole there and the butterfly valve covers a portion of it when closed. I was able to look really closely at that hole in each carb and adjust them so they were all the same. Your carb may be slightly different but you may be able to find a similar visual reference point. If you're eyesights not so good, get a reading magnifying glass to help. These pictures (not mine) really illustrate what I'm talking about www.xs11.com/forum/showthread.php?t=36021

As far as synching all four, I think there is an order though someone else will need to confirm (I own a twin) but I think you sync the left two then the right two then the middle. Or is it middle first then outer?

I made one virtually identical to that - a manifold w four 10' sections of clear tubing & 2-cycle oil as the fluid. My bike has mechanical slide carbs, so I did the initial mechanical synchronization beforehand. Then I used the homemade device. As far as I can tell, it worked fine. But like many others, I'd like to compare it to a "professional" manometer.

Here's a homemade one that might be better than the professional models. Further down in the thread is a diagram that shows what's in it. I think the guy should patent and sell them. Ed

kzrider.com/forum/21-tools/569922-latest...nch-manometer#570898

Left side of brain says just to see equal vacuum pull.. well ok I guess...
Right side of brain says "Oh Hell No"....

As in a good vacuum set (Morgan or Lou's digital design)you're not only syncing to equal values but you are seeing what the vacuum measurements are. Sure, some will say not important but I call bull shit on that one.... Even the OEM manuals state a vacuum range specification, so yeah it matters for optimum performances desired..

Case in point to your question...
I first purchased a 4 set of the cheap vacuum gauges, after completing with some fluctuating measurements ( ) thought all good.

Did the engine start and run, yup but something still wasn't right in idle performance or mid range rpm pull....

Did some research and a carb tune mechanic gave me a link to the Morgan...
Obtain, hooked up and my measurements for the analog gauges where all over the place.
Re-synched using the Morgan, Regarding performance... Oh yea now we're talking.

Same time, I'd still like to hear about a comparison result with a Morgan or Lou's...

where do i find that much clear tubing?

Old Man Rock wrote: Left side of brain says just to see equal vacuum pull.. well ok I guess...
Right side of brain says "Oh Hell No"....

As in a good vacuum set (Morgan or Lou's digital design)you're not only syncing to equal values but you are seeing what the vacuum measurements are. Sure, some will say not important but I call bull shit on that one.... Even the OEM manuals state a vacuum range specification, so yeah it matters for optimum performances desired..
....

I've thought about this. If a bike is in good condition w very good compression across the board w the stock airbox properly installed w a new air filter w good/pliable airbox ducts & carb holders & no vacuum leaks w carburetors in very good condition & recently thoroughly cleaned & serviced w new o-rings, rubber parts, & gaskets & adjusted as per the FSM w a good ignition system & good battery, and the bike starts & idles fine after doing the initial mechanical synchronization, I was thinking that the vacuum readings would probably fall within the acceptable range?

Without a professional tool, there's always going to be some doubt, though, so it would probably be a good idea to at least get a good vacuum gauge see what kind of readings you're getting. Or go ahead & buy the darn tool. hee hee.

Ok... how Do I adjust these carb sync screws? It has a lock nut and a flathead screw. The book says there is a special tool. I try to back off the lock nut and I feel I am going to break something.

I took mine off and put toothpicks under each throttle plate until they were spaced evenly. that seems like a big tool to have laying around.

donthaveakawman wrote: I took mine off and put toothpicks under each throttle plate until they were spaced evenly. that seems like a big tool to have laying around.

that takes out the fun of building stuff... besides I HATE taking the carbs off the bike it is a total pain.

ironslave wrote:

donthaveakawman wrote: I took mine off and put toothpicks under each throttle plate until they were spaced evenly. that seems like a big tool to have laying around.

that takes out the fun of building stuff... besides I HATE taking the carbs off the bike it is a total pain.

I would like to disagree with you but It is a pain to take them off if you don't need to. also my way is not as exact, there could be leaks around the intakes. my big problem with this thing is the vacuum hoses link together for 2 of the cylinders for the reed valves, how synchronized is that?