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Mercury Carb Synch vs. Ball-Type Carb Synch

  • Thread starter Thread starter suzukizone
  • Start date Start date
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suzukizone

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RE: Carb synch tool for GS850G Carb Synch ('81 GS850GT)

Suzuki shop manual says to use their official "Ball-type" synch tool as there is a differential setting for the two outer carbs and they give the difference based on using this tool. I have the mercury stick type.

1. Is this difference important? My Suzuki dealer says no, just set them all equal.

2. If this is important does anyone have info on how to duplicate the setting with merc stick tool?

Thanks,

DH
 
The shop is correct. I have set carb synch both ways and it makes no noticable difference. I started setting them all the same as of about 10 years ago. LOL

E.


suzukizone said:
RE: Carb synch tool for GS850G Carb Synch ('81 GS850GT)

Suzuki shop manual says to use their official "Ball-type" synch tool as there is a differential setting for the two outer carbs and they give the difference based on using this tool. I have the mercury stick type.

1. Is this difference important? My Suzuki dealer says no, just set them all equal.

2. If this is important does anyone have info on how to duplicate the setting with merc stick tool?

Thanks,

DH
Click to expand...
 
suzukizone said:
RE: Carb synch tool for GS850G Carb Synch ('81 GS850GT)

Suzuki shop manual says to use their official "Ball-type" synch tool as there is a differential setting for the two outer carbs and they give the difference based on using this tool. I have the mercury stick type.

1. Is this difference important? My Suzuki dealer says no, just set them all equal.

2. If this is important does anyone have info on how to duplicate the setting with merc stick tool?

Thanks,

DH
Click to expand...

The mercury manometer is more sensitive and accurate than the the ball type or dial type vacuum gauges. From the Haynes manual:

...Furthermore, it is complicated by the need to set the outer two carburetors at a higher level than the inner two to compensate for the different lengths of the inlet tracts between the inner and outer carburetors and the air filter element...
Click to expand...

If you have a stock airbox, I would follow the advice of the factory shop manual. When the engines are developed they are comprehensively tested on special equipment for best results in a way that can't be matched by seat-of-the-pants judgments. We all know that many typical dealerships have sloppy practices. I would take Suzuki's word on what is best for synchronizing carburetors.
 
I believe it should be noted that the difference we are talking about is 1/2 cm and it should be further noted, very few people can synch carbs accurately to less than 1/2 cm across the board.

In theory, theory and practice are the same. In practice.....................

E.


 
Last edited:
Mercury Carb Synch vs. Ball-Type Carb Synch

First, thanks for all responses.

Well what to do? I have the merc stix, am not planning on buying a set of ball stix as I can only imagine the price from Suzuki.

I can try to compensate, visually, to set them as what I estmate would do the trick but not sure if that is accurate enough to do it. Or I could just set them dead level and be done with it.

I know, I'll watch Seven Samurai again & try to gain insight!

8-[

DH
 
I'll state the situation a different way then. Unless one has a very practiced hand at synching carbs, they will be doing unusually well tobe able to accurately set all four carbs within a 1 to 1 1/2 cm range. Talking about being able to synch cylinders 1 and 4 to 15 cm and cylinders 2 and 3 to 14 1/2 cm is a moot point. LOL

E.


suzukizone said:
First, thanks for all responses.

Well what to do? I have the merc stix, am not planning on buying a set of ball stix as I can only imagine the price from Suzuki.

I can try to compensate, visually, to set them as what I estmate would do the trick but not sure if that is accurate enough to do it. Or I could just set them dead level and be done with it.

I know, I'll watch Seven Samurai again & try to gain insight!

8-[

DH
Click to expand...
 
Mercury Carb Synch vs. Ball-Type Carb Synch

I am struck mootless!

Thanks, will humbly proceed and burn incense. Appreciate the assistance.

DH:-D
 
I just purchased a mercury manometer and ran into a slight problem where what I assume is fule is now sitting on top of the mercury in each of the tubes... Ironically there appears to be nearly the same amount of fuel in each tube so it shouldn't overly affect my (dis)ability to snyc the carbs. Has anyone else run into this? Any suggestions for cleaning the fuel out and preventing this in the future?
 
I'd suggest going through your carbs again, or checking your petcock. You're getting too much fuel into them. Remember that the manometer is sitting as close to the valvetrain as possible. If you're sucking fuel into the manometer, then you can only imagine what is getting into the pistons. It's definitely creating a rich condition.

Brad bt
 
I thought that as well, when I did a plug chop at idle they looked a bit rich but when i adjusted the air screws to highest RPM when I leaned the carbs out anymore it would drop in RPMs...
 
I just did my sync and set the outer 2 at 2cf's higher than the middle ones and it works for me .there is a sight on syncing the cv carbs that also say's 2 1/2 to 3cf's for the outer one but who can get that close anyway.If your all stock just make sure the outer 2 are a little higher.You might notice a little less vibration but that's about it.
 
Can`t get mercury sync sticks in Ca any more due to the tree huggers because of the mecury:-({|= I have found the BEST sycronizing tool ever!! I have used gauges and mecury and the balls, this tool is a electronic sync tool. It comes from MOTION PRO and it is all LEDs in four bar graphs and it will do engine diagnostics at the same time:shock:. It is alittle expensive ($600) but if you have a lot of bikes that are inline fours it will pay for itself big time. I know this... the carb syncs that I have done with this tool vs the old style is dramatic[-o<.
 
Nightmare said:
I thought that as well, when I did a plug chop at idle they looked a bit rich but when i adjusted the air screws to highest RPM when I leaned the carbs out anymore it would drop in RPMs...
Click to expand...

How much fuel is getting into the sticks? It may just be a small amount, which could explain the reason for not having a serious problem. Is it fuel? Or is it possible a bit of condensation was able to work it's way into the manometer tubes?

Brad bt
 
On the vacuum guages, the vacuum is applied at the cylinder end. Or to rephrase, the cylinder is sucking on the tube to draw the mercury up the guage. For fuel to go into the guage, the draw would have to be reversed and the guage would be sucking. I've heard people complain that mercury guages suck before, but not literally. LOL

E.


Nightmare said:
I just purchased a mercury manometer and ran into a slight problem where what I assume is fule is now sitting on top of the mercury in each of the tubes... Ironically there appears to be nearly the same amount of fuel in each tube so it shouldn't overly affect my (dis)ability to snyc the carbs. Has anyone else run into this? Any suggestions for cleaning the fuel out and preventing this in the future?
Click to expand...
 
LOL, its not a termendous amount of fuel (roughly 1cm in each of the little glass tubes, which should equate to about 20mL or less). I was wondering about condensation but I had run the bike before doing the sync so I would have thought that would have cleared out any water left over...

However, an "interesting note" is that on occasion when i've pulled the carbs off shortly after killing the engine i've notice a little white cloud of "mist" coming out of the intake manifold (and have seen this "mist" oscilating within the vinyl tubes of the merc sync)... perhaps since I had run the bike before and when i shut it off it caused the evaporated fuel to condense and flow to the lowest point?
 
Sorry to hijack, but Earl, are you saying to set all cyls to the same vacuum, even on bikes with a crossover pipe? My understanding was with CV carbs and a crossover exhaust pipe, 1inch of vacuum lower for 2&3, and that this was a fairly important aspect of carb tuning...

Makes me wonder if my long-standing vibration issue would be any better with even vacuum across the board...
 
I have some mercury gauges and set the center two carbs about 1cm below the outer carbs. It takes time to get everything right so don't forget to place a fan in front of the bike blowing on the engine.
 
Nessism said:
I have some mercury gauges and set the center two carbs about 1cm below the outer carbs. It takes time to get everything right so don't forget to place a fan in front of the bike blowing on the engine.
Click to expand...

Hmm... there's a bit of difference between and inch and a cm. ;-) My manuals (Clymer and Suzuki shop) both just refer to the Suzuki balancer with it's balls and half-balls, so no authoritative ruling from there...
 
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