• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

bench synch?

  • Thread starter Thread starter mtalneck78
  • Start date Start date
M

mtalneck78

Guest
How do you bench synch a set of carbs? I have just done a dip & rebuild of my 79 gs750 carbs & would like to know how this is done.
Also, where is a good source for replacement O rings for the intake boots?

thanks, Dan C.
 
Last edited:
If you do a search on bench synching you will get several hits with regards as to how to do it. The o-rings can purchased from Robert Barr, also available from this site, just do a search.

Scud
 
http://www.cycleorings.com/ is the Robert Barr site, but I don't believe he sells intake manifold O-rings, (only info on how to tell if they need to be replaced). His O-ring kits are for carb rebuilds.

Bikebandit.com is where I got mine. Your Suzuki dealer will have them as well. Make sure you use the OEM ring and not some other replacement as they are made specifically for that purpose. Other rings won't hold up.
 
To bench sync use a fine piece of stiff wire to set all the throttle plates, butterflies, to the same gap. Start with #3 carb since that is your carb with no individual adjuster in most cases. Use the main throttle stop to set #3 to where the wire slides snugly at the very bottom of the plate. Then use the individual adjusters on the other three carbs to set the gap the same. This is generally close enough to get a bike to run fairly decent. You'll need gauges to get them spot on.
 
Once again, I forget how to post a link.:roll:
I gave detailed VM bench synch info at an old thread.
Search this: Tech section, thread title: "78 GS1K carb rejet, bad fuel economy, Keith Krause". 4th page, 36th reply. Gotta remember how to post a link.
Also, if any doubt if you have a "master" carb, just look to see if there's an adjuster screw above the slide. If not, adjust the other three to match its slide. If there is a screw, start with any carb.
For best performance, you must vacuum synch with a vacuum tool after the bench synch. Always set ignition timing before the vacuum synch.
 
Just realized we are talking VM's. You'll have to use the wire or whatever you use to gauge the gap under the slide.
 
KEITH KRAUSE said:
Once again, I forget how to post a link.:roll:
I gave detailed VM bench synch info at an old thread.
Search this: Tech section, thread title: "78 GS1K carb rejet, bad fuel economy, Keith Krause". 4th page, 36th reply.
Click to expand...

http://www.thegsresources.com/_forum/showthread.php?t=80632

text below...

KEITH KRAUSE said:
The VM bench synch.
FULLY CLOSED POSITION first ('78/79 GS1000): Take the tops off the carbs. Throttle return spring INSTALLED. Be sure the throttle valve arms and throttle pulley are torqued to the throttle shaft and the throttle shaft stopper plate is tightened.
Turn the idle adjuster knob to make a good clearance between its tip and the throttle pulley. Above each slide is the slotted adjuster screw and its holding nut. Loosen the holding nuts. Hold the carbs with the ENGINE side facing you. Look at the small nick at the bottom of the slide. When done, you want these to all look as close to uniform as possible. On the 1000, you can start with any carb. Turn the slotted screw to fully close or seat, the throttle valve. Don't tighten it down. Just seat the valve. When you see the valve stop dropping, stop turning the screw. You'll find that the screws are very sensitive. It does take decent eye sight and a careful hand. Once the valve is fully closed, hold the adjuster screw STILL and tighten the holder nut to 3.5 ft/lb. NO MORE. Repeat to the others. When done, the small nicks should look uniform.
Now the FULLY OPEN POSITION: There's a slotted screw under spring tension mounted on the carb bracket. When you open the throttle fully, the pulley will stop when it hits this screw. Turn the carbs so the FILTER side is facing you. Raise the valves by pushing up the throttle pulley until it stops and hold it. Look up and inside the bore. Note the bottom of each valve. The bottom of all the valves must be between .5mm and 1mm above the top of the intake chamber. Turn the slotted screw in to decrease the gap, out to increase. It usually only takes a 1/2 turn or so, if needed.
Now turn up the idle adjuster knob enough so the bike will idle when you do the vacuum tool synch.
A good bench synch will make the vacuum synch easier/quicker.
Use two fans. Stop if you think the motor's getting too hot. Remember to adjust the side air screws by using the highest rpm method before the synch. This is to be done on a warmed up engine. The ignition timing, tappet clearances, and throttle cable slack must be correct too. Clean and oil those K&N's with K&N filter oil and mount.
Note the initial vacuum levels at start up. I synch at about 3,000 rpm's. Don't rev the bike suddenly or you'll suck up mercury. Easy on the throttle. Adjust the higher level(s) to match the lower levels. Don't over tighten the adjuster screws. Get the levels as close as possible. If you can get them so the difference between the highest and lowest level is about 1/2", that's good. Double check all adjustments by slowly opening/closing the valves. It takes practice. You can do it.
Click to expand...
 
Thanks Paul.:oops: If it's easy enough, can you describe how to post a link? I keep forgetting. Be detailed because I'm computer illiterate. I'll right it down this time. I just can't get along with this computer stuff.
 
No problem, putting a link in a post is actually easier with this forum software than is used to be.

When you are on the page whose link you want, click in the address bar. (It's usually on the top of the window and has the http:// etc in it) When you click on the address, it should highlight the whole thing.

When it is all highlighted, either 1) hold down the Ctrl key and hit the C key, or 2) right-click on the address and select Copy.

Go to the window where you are writing your post and click in your post where you want the link to be.

Either hold down the Ctrl key and hit the V key, or right-click where you want it and select Paste.

The link should appear - there is no need to select or type the tags like in the old forum. If it ...I can figure out what's going on. Have fun.
 
Thanks so much for the help. Once again this forum has helped me get my GS back on the road.
 
mtalneck78 said:
How do you bench synch a set of carbs? I have just done a dip & rebuild of my 79 gs750 carbs & would like to know how this is done.
Also, where is a good source for replacement O rings for the intake boots?

thanks, Dan C.[/QUO www.bikebandit.com for the o-rings, a buck a piece
Click to expand...
 
Thanks Paul for the link sending info.:) I'll print it out and try it next time.
 
You must log in or register to reply here.
Back
Top