Carb Sync on 2006 GS500F Anyone else have this issue?

[ILuvMickeyMouse2]

Wow, I decided to sync the carbs on my wife's GS and having done it frequently on my Yamaha FJ1200 (4 carbs are better than 2! LOL) I expected no issues. Boy, was I wrong!

In addition to having the OEM fuel lines crumble as I attempted to remove tank, I ran into 2 issues, one of them ridiculous, and I have to find out if others have this as well.

First, when installing the new fuels lines to the petcock, I ended up having to shave one side of both hoses where they connected to the petcock because the new hoses (standard aftermarket) were thicker wall and it was impossible to get both hoses on the nipples as they are WAY TOO CLOSE TOGETHER! And even when I got the newly shaved hoses on the nipples the clamps hit against each other. I noticed that one nipple (the reserve, I think) was longer. This has to be because Suzuki knew of the issue and made it longer to allow for the tightening of the clamps. But why didn't they simply design a new petcock? And as her bike is a 2006, did all previous models have this issue?

Second, and this is the one that really "over-baked my cookies", the vacuum caps on the test port nipples are in impossible locations to get to!

The one on the right carb is tucked down behind the plug for the O2 sensor (I'm guessing that's what it goes to). Now, that wouldn't be so bad if I could unscrew the plug mount but I can't because the screw is located about 3/4" away from and BEHIND the frame! The port for the left carb is in the same location on the intake sleeves but that puts it in between the carb body and all the cables, adjustment screws, etc. I could probably take it off with my long-nose pliers but I was afraid I might not get the wire clamp back on after as there's no room to squeeze it. But it's also virtually impossible to attach my vacuum gauge hose.

So, in the end I adjusted them by ear. And thanks to my previous long-term experience doing mine, I got hers remarkably close to perfect. The adjustment got rid of the annoying pop she had when cold and the increase in horsepower is very noticeable. It starts much better cold and is very smooth through all power bands.

But I simply had to come here and see if this is the way all GS's are. This is the WORST design I have ever seen on a modern era bike, of basically any mechanical system! To do this right you'd either have to un-bolt the motor mounts and remove the O2 sensor from it's mount to gain access to the right carb and for the left, I guess I'd be best off by removing ALL the linkage and install some home-made tube extensions and the put nipples and rubber plugs on in such a way that I could easily get to them in the future.

Sorry for the length of this but I wanted to make it a clear message and see if everyone else has these issues and hear any easy fixes or different ways to sync the carbs. I read one post on here about using solid core wire to make sure both slides are in identical position but that's not a very accurate way to balance the vacuum, which is what controls the diaphragms, not position.

I'd love to hear from you experts, and back yard tinkerers. HELP! LOL

[gsJack]

Doubt I'll be much help on this one but just can't resist commenting anyway. 

Did 11 valve checks on my 97 GS while putting 80k miles on it and 13 valve checks so far on my current 02 GS while putting 100k miles on it not to mention various other reasons to pull the tanks and have yet to replace a fuel line or hose clamp or even seen a need to do so.   

Never have done a carb sync on a GS or seen a reason to do one.  If I don't unsync my carbs I don't need to sync them.  My carb golden rule for myself is "Don't mess with your carbs and they won't mess with you."

By the way the tank petcock is the same on all years 89-09 GSs:

http://img.photobucket.com/albums/v443/jcp8832/GS500fuelcocks_zpsfcb7992c.jpg

Just the ramblings of an old man who probably should have hung up his helmet a long time ago.   

[The Buddha]

GS carbs can be synched with them off the bike pretty well ... I know of people who use drill bits, feeler guages etc etc, but I do em by eyeball and sunlight ...
The fuel lines are ridiculous, which bike has 2 stupid petcocks in the first place ... Dumb design.

And yes GSJack is right carb synchs are for people who "unsynched' their carbs.
Sadly, that encompasses a vast number of gorilla mechanics who never understood the science behind synching carbs, and do so with valves that are wildly out of synch (remember they can be in spec but not equal to each other) if left cyl intake is @ low end of clearance and right is @ high end, you'd easily synch the carbs up and end up with the carbs out of synch as soon as you do a valve adjustment.

Factory sets the carbs by feeler guage, and they set their engines with off size shims to get the clearance they need. Have you opened a motor and found a valve shim that has a number like 258 or 262 - Yea, we cant buy those, 255, 260, 265 are all we get.

Anyway synch away ... and fuel lines usually get rotted out due to sun exposure, the protective sheath should like protect more ... and once in a while try replacing that. The Lines may last longer.

Cool.
Buddha.

[Suzuki Stevo]

If it was that simple there would be no bias screw or TB adjustments on every multiple cylinder engine.

I check the balance on all my multiple cylinder bikes at least once a year, they are never where I left them the last time, your confuzing ballparking the carbs with an actual sync to the state of the engine...because that's really what syncing is, making the gap the same on the carbs is not syncing anything at all.

[The Buddha]

If it was that simple there would be no bias screw or TB adjustments on every multiple cylinder engine.

I check the balance on all my multiple cylinder bikes at least once a year, they are never where I left them the last time, your confuzing ballparking the carbs with an actual sync to the state of the engine...because that's really what syncing is, making the gap the same on the carbs is not syncing anything at all.

On a GS with intake valves set very close to each other and cyls with similar wear - essentially all motor related being equal - eyball synch is going to be very very close to vacuum synch.

No one synch these to the state of the engine. Past about 1/8th throttle synch is basically forgotten (unless you're so wildly out of spec) that it does matter. Eyeball/other shim method is plenty good on the average GS.

Cool.
Buddha.

[Suzuki Stevo]

author=The Buddha
"On a GS with intake valves set very close to each other and cyls with similar wear - essentially all motor related being equal - eyball synch is going to be very very close to vacuum synch."

First off  there is nothing so special about the GS engine that makes it immune to what makes all other multiple cylinder multiple Carb/TB engines need a proper sync to pull with both Carbs/TB's as a team off an idle. I do agree that the farther you get off an idle the less sync comes into play, but then I have been saying that for the 35+ years I have been syncing carbs.

And remember, you will never achieve this eyeballing  your carbs with a drill bit...



author=The Buddha
"No one synch these to the state of the engine"   

Compost again, the relationship between the Carb/TB's never changes, the engine they are bolted to does however.

author=The Buddha
"Eyeball/other shim method is plenty good on the average GS."

Again...there is nothing so special about the GS engine that makes it immune to what makes all other multiple cylinder multiple Carb/TB engines need a proper sync to pull with both Carbs/TB as a team off an idle.

We have had this discussion a number of times, please learn that what you are spouting is not taught by anyone that actually works in the MC repair field, it is just your opinion and nothing more 

[gsJack]

Naaa, I'll still do it my way, if the seat of my pants tells me it's ok then it's ok with me.  Gotta stick to my basic principles, if it ain't broke don't fix it, don't mess with your carbs and they won't mess with you, and it ain't rocket science it's more like tractor science.  Ignorance is bliss!   

[Suzuki Stevo]

Naaa, I'll still do it my way, if the seat of my pants tells me it's ok then it's ok with me.  Gotta stick to my basic principles, if it ain't broke don't fix it, don't mess with your carbs and they won't mess with you, and it ain't rocket science it's more like tractor science.  Ignorance is bliss!   

If your happy, that's fine, I am just stating that setting the butterfly's the same is not a sync, every year the balance changes, even though the carbs have not been touched. If you can rotate the throttle just off an idle and it pulls smooth, your close enough, if you rotate the throttle and it hesitates and your carbs are fine...your sync may be off. It has never been a "Set & Forget" item. I have never hooked up my manometer and found any two carbs anywhere near close, and it get's even worse with 4 carbs, they are always all over the place.

Once you get above 2,000 Rpm sync doesn't matter anyway, carb/TB sync is all about making all the cylinders work as a team, just off an idle. 

[gsJack]

Once you get above 2,000 Rpm sync doesn't matter anyway, carb/TB sync is all about making all the cylinders work as a team, just off an idle.

Who runs a GS500 below 2k rpm?  Ever?  Not me so I am happy with it the way it is.  Runs as good at 100k miles as it ever did.  I'd be happier with less oil consumption at 100k miles so maybe that would be better if I kept it below 2k rpm.    

[Suzuki Stevo]

Who runs a GS500 below 2k rpm?  Ever?  Not me so I am happy with it the way it is.  Runs as good at 100k miles as it ever did.  I'd be happier with less oil consumption at 100k miles so maybe that would be better if I kept it below 2k rpm.   

Carb balance is all about coming off an idle smoothly. So you never have to transition from an idle? I'm pretty sure you do, if your GS does it without hesitation, then ride on.

[gsJack]

I'm riding on.   But just not as often, as far, or as fast as I used too.

[The Buddha]

Naaa, I'll still do it my way, if the seat of my pants tells me it's ok then it's ok with me.  Gotta stick to my basic principles, if it ain't broke don't fix it, don't mess with your carbs and they won't mess with you, and it ain't rocket science it's more like tractor science.  Ignorance is bliss!   

If your happy, that's fine, I am just stating that setting the butterfly's the same is not a sync, every year the balance changes, even though the carbs have not been touched. If you can rotate the throttle just off an idle and it pulls smooth, your close enough, if you rotate the throttle and it hesitates and your carbs are fine...your sync may be off. It has never been a "Set & Forget" item. I have never hooked up my manometer and found any two carbs anywhere near close, and it get's even worse with 4 carbs, they are always all over the place.

Once you get above 2,000 Rpm sync doesn't matter anyway, carb/TB sync is all about making all the cylinders work as a team, just off an idle.

Every year it will change cos there is wear ...
I'm also with GSJack in that sense - you will never feel it on eyeball vs mercury vs guages when riding or even when idling if the motor is in good shape. If the motor isn't in good shape - eyeball synch is better.

Cos with vacuum synch its easy to set the carbs to compensate for motor. It will idle perfectly but be terrible everywhere else. If you did it by eyeball ... it will be terrible everywhere ... guess its not better after all.

I dunno eyeball synch is close enough on most GS'es ... and

Who synchs their carbs every year vacuum or eyeball

Cool.
Buddha.

[ace50]

Never have done a carb sync on a GS or seen a reason to do one.  If I don't unsync my carbs I don't need to sync them.  My carb golden rule for myself is "Don't mess with your carbs and they won't mess with you."

Wow! Never seen a bike that a carb sych didn't help!
Granted, I've worked on other peoples bikes and I'm amazed at the crap they put up with or don't care to fix or maintain.

[gsJack]

Never have done a carb sync on a GS or seen a reason to do one.  If I don't unsync my carbs I don't need to sync them.  My carb golden rule for myself is "Don't mess with your carbs and they won't mess with you."

Wow! Never seen a bike that a carb sych didn't help!
Granted, I've worked on other peoples bikes and I'm amazed at the crap they put up with or don't care to fix or maintain.

If a bike needs a carb sync doing it should help but if it doesn't need it I don't do it.  Neither of my GS500s have needed it. 

[ace50]

"If a bike needs a carb sync doing it should help but if it doesn't need it I don't do it.  Neither of my GS500s have needed it."

How would you know that?
That's like guessing the RPM of an engine without a tach, guessing the the pressure in a tire without a gage, or never replacing spark plugs cause it seems to run fine.
Never mind, That will ALL work, if you want it to.

[gsJack]

..........................If you can rotate the throttle just off an idle and it pulls smooth, your close enough, if you rotate the throttle and it hesitates and your carbs are fine...your sync may be off...................................Once you get above 2,000 Rpm sync doesn't matter anyway, carb/TB sync is all about making all the cylinders work as a team, just off an idle.

Good points Steve, I got out for a bit of a ride yesterday and made it a point of slowly rolling the throttle off idle and slowly revving it up a number of times as well as snapping it open as fast as my ageing wrists would permit after it was thoroughly warmed up and my 100k mile GS with carbs that were never touched performed flawlessly without hesitation.

Of course when I say my GS doesn't need carb syncing I am not just totally guessing it doesn't because I blip the throttle a few times to check it every time I ride it before riding off regardless of ambients.  When it's cold out it needs a proper choke setting to respond quickly and smoothly and riding year around here in NE Ohio I am still riding off in a couple of minutes smoothly and balk free.

[gsJack]

I find it interesting that the Suzuki GS Maintenance Charts make no mention of syncing carbs but do cover intervals for oil and filter changes, valve checks, spark plug changes, brake checks, tire checks, etc.  Typical GS Maintenance chart found in Owners Manual:



While briefly looking thru a Suzuki GS Shop Manual to see what they say about syncing carbs I find the procedure covered after the section on carb assembly.  Could it be they too think carb syncing is only required after carb unsyncing?   

Having glanced thru many a thread here on adjusting the pilot screws with little interest I was amused to find this in the shop manual:



So believe it or not I do change my plugs every 6k miles sooner than Suzuki specs, and I have changed my oil every 2-3k miles for 180k GS miles sooner than Suzuki specs, and I have checked my valves 24 times during the 180k GS miles at intervals I deem appropriate, and I do glance at the tach from time to time to observe rpm's but have a pretty good feel for what they are before I look.

And I still believe if it ain't broke don't fix it and don't mess with your carbs and they won't mess with you.    

[Suzuki Stevo]

TIP: For those that want to check their sync, add an extension hose to the left carb the first time you sync (not sure what years have the vacuum port in this location?) this makes the process much easier in the future.




Sync Process

• You will need an external fuel source
• Bike needs to be up to operating temperature
• Adjust bias screw at an idle (1500 Rpm optional)

You are done when you see this...

[gsJack]

The 89-99 Shop Manual calls for setting idle at 1750 rpm while balancing carbs.

[Suzuki Stevo]

The 89-99 Shop Manual calls for setting idle at 1750 rpm while balancing carbs.

Nah...I have been syncing carbs long before the GS500 went into production, an idle or just above (1,500 as I stated) works just fine, no need to over think a simple process, my current manometer is over 35 years old, I have done this a time or two, I tend to go with an idle, the 1,500 Rpm is a number I came up with because it is just above an idle 

EDIT: It's Exactly like what you do with the valve lash specs, I have my own numbers that over the years have proven themselves, regardless what the manual says