Are these any good for carb sync/balancing ?

[Steve]

but on the GSs should you adjust so carb 1 and 4 are slightly (1 cm2) higher than 2 and 3?

thats what the service manual calls for
but the explanation given that the outer cylinders have a "longer intake" just didnt make sense to me so i adjust them all equally 8-[

That's the first time I have heard that reasoning. I have heard a couple of theories before, but never any hard fact.
1. The inner cylinders run hotter because they are in the middle. By giving them a bit more mixture, they run cooler. I'm not sure I buy this theory because if you give them more mixture (that's more, not richer), they will do more of the work and burn hotter.
2. This difference in vacuum only applies to the bikes that have the balance tube in the exhaust between cylinders 2&3. Older bike without the balance tube and bikes with 4-into-1 pipes should set the vacuum equally in all cylinders. I suppose there might be some logic to the difference in back pressure, but have not yet figured out why it requires a different throttle sync setting. And who designed that balance tube between just two cylinders anyway? While a balance tube between the pipes just ahead of the mufflers has been proven to add power and reduce noise, this pipe between just two cylinders only appears to give the bike a unique sound, and on the L models, it's not that pleasant.

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[Guest]

2. This difference in vacuum only applies to the bikes that have the balance tube in the exhaust between cylinders 2&3. Older bike without the balance tube and bikes with 4-into-1 pipes should set the vacuum equally in all cylinders. I suppose there might be some logic to the difference in back pressure, but have not yet figured out why it requires a different throttle sync setting. And who designed that balance tube between just two cylinders anyway? While a balance tube between the pipes just ahead of the mufflers has been proven to add power and reduce noise, this pipe between just two cylinders only appears to give the bike a unique sound, and on the L models, it's not that pleasant.

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hm, since pipes 1&2 and 3&4 are inter-connected (going into the same muffler), doesnt that ballance tubes between 2&3 then practically mean that they are ALL interconnected (all 4 pipes /cylinders)?

 

[Guest]

That's the first time I have heard that reasoning. I have heard a couple of theories before, but never any hard fact.

from the haynes manual, and i quote:

"... the (balancing) procedure is complicated by the need to set the outer two carbs at a higher level than the inner two to compensate for the diferent lengths of the inlet tracts between the inner and outer carbs and the air filter element."

 

[Steve]

hm, since pipes 1&2 and 3&4 are inter-connected (going into the same muffler), doesnt that ballance tubes between 2&3 then practically mean that they are ALL interconnected (all 4 pipes /cylinders)?

Normally you would think so, but the balance tube is roughly 12 inches upstream of where 1&2 and 3&4 come together, so if it is going to try to have any effect on balancing 1&4, their exhaust pulses are going to have to reverse themselves and go back up the "Y" toward the balance tube. Somehow, I just don't see that happening. :-s

from the haynes manual, and i quote:

"... the (balancing) procedure is complicated by the need to set the outer two carbs at a higher level than the inner two to compensate for the diferent lengths of the inlet tracts between the inner and outer carbs and the air filter element."

Until just a couple of weeks ago, I have only had the Clymer and Suzuki manuals at my disposal. So far, we have been too involved in getting the bike apart, repaired and put back together to stop and read the Haynes manual that came with it. 8-[
The Clymer manual only says that the '80 and newer bikes use the different setting, with no explaination why.
The Suzuki manual only gives the desired reading for the ball position, again, with no explaination.

Of particular note: the Suzuki "special tool" has no numbers on it. The calibration procedure has you set each ball in the center of the tube, then connect the tool to the individual runners. The balls appear to be no more than 1 cm in diameter, and the difference that is called for is half a ball, so about 0.5 cm.

Maybe Rapid Ray or one of the other racers out there can tell us how much the matched intake tracts affect tuning, but it seems to me that the difference from the airbox to the valve isn't more than 1/2 inch different from one cylinder to another.

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[Guest]

Maybe Rapid Ray or one of the other racers out there can tell us how much the matched intake tracts affect tuning, but it seems to me that the difference from the airbox to the valve isn't more than 1/2 inch different from one cylinder to another..

yeah, that is what i dont get...

the airbox is more or less rectangular, it has a wide intake opening at the back and some holes at the bottom
once the air gets to the airfilter, again the opening is rectangular and streches pretty much along the whole width of the four rubber boots
so, i really dont see where that difference in the lenght of intake would be

 

[lurch12_2000]

I should have been more specific in carb 2 and 3 being slightly lower on only the bikes with the crossover(such as my GS1100G stock exhaust).
But I was trying to point out that in the "balance your carb in 45 seconds" youtube link in this thread, it appears that he still had some variation between carbs.
Do you people who use this carbtune tool get their's exactly the same or closer than this video?

 

[Guest]

Do you people who use this carbtune tool get their's exactly the same or closer than this video?

more like in the video
i find that as you change the rpms (in the lower rpm range) you get some change in the INDIVIDUAL readings
so, i use an aproximation accross the different rpms (1500-4000rpm)

 

[82Shafty]

I set my vacuum sync specs as 8" on the inside and 10" on the outside. Bike seems to run like an ape.

82 GS1100GL

I did not veryify with the manifold series to sync all four gauges, I suppose I will try it to see how they pan out. I've only manually adj gauges when not hooked to a common vacuum source.

 

[Shin-Ken 1074]

Thanks for the offer lurch12, would love to see the setup and swap 1100G stories with you, just need to do some more work on the snorkel mod and shark cage before I drop in, cheers.

P.S. A local Suzuki dealer here was selling his last set of genuine vacum gauges (mercury) for AUS$140 and I let it go at the time, dohh!

 

[Shin-Ken 1074]

Hi tone, thanks for the tip on the Morgan Carbtune Pro, for that price delivered to Oz and the positive feedback its getting I'll be considering a set, cheers.

 

[jeff.saunders]

I use a set just like those.

You need to recalibrate all 4 dials to 1 cylinder every time you use it.remember that!!, but no mercury is why I went this way.
it takes a little more time but not that much.

they are worth 2X weight in gold.

I got mine from K&L no middle man fee (z1Ent)
regulators stop the bouncing and you'll develop a technique with a little experience you'll have it down pat -- after you DE-tune your bike and then bring it back is what taught me.


it is really easy to make your bike slower BUT when you make a buddy's bike faster and smoother you'll have free beer for a long time

Guess what... K&L is a middle man... we bypass K&L and buy from the same place they buy from...