Major differences when syncing carbs at various RPMs

[UncleMike]

I like beer ok, but there is only one beer I like.
Earl

And it's made about 30mins from me!

 

[49er]

Earl
I told you that my Morgan Carbtune wasn't for sale. And when you borrowed it I said, be careful not to loose the mercury.:-D
Cheers.

 

[earlfor]

The Morgan is the Cat's meow for carb work. Use one once and you'll never go back. I didnt lose the mercury, I took it out and put it in the fish tank. BTW, anyone know how much fish food to feed per day for a couple of 9 foot goldfish?

Earl

Earl
I told you that my Morgan Carbtune wasn't for sale. And when you borrowed it I said, be careful not to loose the mercury.:-D
Cheers.

 

[UncleMike]

The Morgan is the Cat's meow for carb work. Use one once and you'll never go back. I didnt lose the mercury, I took it out and put it in the fish tank. BTW, anyone know how much fish food to feed per day for a couple of 9 foot goldfish?

Earl

As much as they want!

 

[Road_Clam]

I drink beer, but I have noticed my hard liquor intake has increased since I started working on my bike......

I know the feeling...... I restored a GS1100E, and in the process became an alcaholic. Oh well, I do have a nice bike.......

 

[t3rmin]

The Morgan is the Cat's meow for carb work. Use one once and you'll never go back.
Earl

To the completely Morgan uninitiated, it seems like it'd take lots of time to put it in, adjust, put it in the other cyls, check for balance, lather, rinse, repeat. Do you use it for balancing or just jetting or what? Or do you do a vacuum balance and throw in the carbtune to check it afterward? In other words, gimme a little overview of how you personally use the thing. I'm curious now. ;-)

 

[49er]

Morgan is an Irish company who as Earl rightly points out, make an extremely good carb syncing tool. They make Carbtunes for engines up to six cylinders.
Their design is similar to the suzuki model that was available when our GS's first appeared. The difference is that they use stainless steel rods instead of a balls in their indicator tubes and they don't need to be re-calibrated each time you use them.
Morgan's instructions advise doing the sync at the manufacturer's suggested rpm, in the 850's case 1500-2000rpm (Clymer 1979-1984 GS850-1100). They also advise against doing syncs at higher rpms.
However, they have overlooked one valuable piece of advise. There is no recommended number of beers to be consumed during the syncing process.
Cheers

 

[UncleMike]

However, they have overlooked one valuable piece of advise. There is no recommended number of beers to be consumed during the syncing process.

The answer to this question is the same as to the universal question we all get asked:

Q - How many beers did you drink last night?
A - All of 'em.

 

[t3rmin]

Morgan is an Irish company who as Earl rightly points out, make an extremely good carb syncing tool. They make Carbtunes for engines up to six cylinders.
Their design is similar to the suzuki model that was available when our GS's first appeared. The difference is that they use stainless steel rods instead of a balls in their indicator tubes and they don't need to be re-calibrated each time you use them.
Morgan's instructions advise doing the sync at the manufacturer's suggested rpm, in the 850's case 1500-2000rpm (Clymer 1979-1984 GS850-1100). They also advise against doing syncs at higher rpms.
However, they have overlooked one valuable piece of advise. There is no recommended number of beers to be consumed during the syncing process.
Cheers

I think Earl is talking about the clear sparkplug thingy, no?

 

[49er]

No. He is talking about the vacuum indicating carburettor synchronising tool which you attach to the individual inlet tracks to synchronise your engines carburettors while the engine is running.:-D In the case of VM carbs, the slides are adjusted until all vacuum readings are equal, or within 2cm/Mg.

 

[t3rmin]

No. He is talking about the vacuum indicating carburettor synchronising tool which you attach to the individual inlet tracks to synchronise your engines carburettors while the engine is running.:-D In the case of VM carbs, the slides are adjusted until all vacuum readings are equal, or within 2cm/Mg.

Oh, duh. I was confusing that with the COLORtune. ;-) Never mind!

 

[Nessism]

No. He is talking about the vacuum indicating carburettor synchronising tool which you attach to the individual inlet tracks to synchronise your engines carburettors while the engine is running.:-D In the case of VM carbs, the slides are adjusted until all vacuum readings are equal, or within 2cm/Mg.

I thought the center two cylinders are supose to be sync'ed with a slightly lower vacuum level?

 

[txironhead]

I know the feeling...... I restored a GS1100E, and in the process became an alcaholic. Oh well, I do have a nice bike.......

I am NOT an alchoholic, I'm a drunk. Alchoholics go to meetings......<hic>

Whar's tha damn wrhench? It was here a minnit ago.......\\/

 

[UncleMike]

I am NOT an alchoholic, I'm a drunk. Alchoholics go to meetings......<hic>

Whar's tha damn wrhench? It was here a minnit ago.......\\/

AA is for quitters.

 

[49er]

Hey you drunks, the man's asked a sober question.
The CV carbs on engines of 1980 vintage onwards have the vacuum on 2 & 3 carbs slightly lower than for 1 & 4.
Because there is no throttle valve adjustment screw on #3 carb, all the others need to be synced to this one. I don't know why the middle carbs are different to the outer ones but suspect that the slightly richer fuel mixture would help to keep those cylinders running at similar temperatures as 1 & 4 where more direct airflow is available for cooling.
My 850 definately runs hotter on the inboad cylinders, as was confirmed by the browner oil discolouration marks adjacent to the exhaust valve bucket galleys.
The VM carbs on 79 engines are synced equally.

 

[tconroy]

This thread is just too funny. Don't take my input the wrong way, but this whole "dog and pony show" about the need to synch at different RPM's IMO is a total waste of time on a STREET driven motorcycle. If Suzuki felt it was that critical, they would have outlined a totally different procedure in all their service manuals. You guys can certainly do whatever you feel comfortable with. For me, I synch per the factory manual, then forget about it, and just ride the thing........

Right on the money Road Clam!!! 1750 rpm's and FORGET ABOUT IT!!!!!!!! No vibration here!!!

 

[U.P.dragracer]

Not exactly. LOL You get the synch off on one cylinder by 2cm and you will find both hands will be numb in less than five minutes at highway speed. In fact, your hands will be numb right up to your elbows.

Earl

LOL heck I dunno I'm a drag racer I never use part throttle anyway LOL!!!

 

[Road_Clam]

I don't know why the middle carbs are different to the outer ones but suspect that the slightly richer fuel mixture would help to keep those cylinders running at similar temperatures as 1 & 4 where more direct airflow is available for cooling.

The middle ajoining carbs are synch'ed at a different level of signal because of the stock exhaust. The 2 center exhaust pipes are joined by a crossover pipe, therefore they scavenge each other. Once you add an aftermarket 4 into 1 system, then you sync your carbs to pull equal vacuum levels.

 

[49er]

Thanks for the info Road Clam.
Was the 79 model stock exhaust not fitted with a crossover/balance pipe? If they were, why weren't the VM carbs synced differently on the inboard cylinders? I run a 4-1 system which performs great with the equal sync method.

 

[KEITH KRAUSE]

Thanks for the info Road Clam.
Was the 79 model stock exhaust not fitted with a crossover/balance pipe? If they were, why weren't the VM carbs synced differently on the inboard cylinders? I run a 4-1 system which performs great with the equal sync method.

Yes it was. '79 1000 factory manual says to synch 2 and 3 just a bit lower than 1 and 4.