• 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.

Is This Right? Carb Question

  • Thread starter Thread starter Colorado CJ
  • Start date Start date
C

Colorado CJ

Guest
I took my carbs off of my GS 550 to get to the intake boots/o-rings. I noticed that the cylinder (the part that holds the large needle) is set lower on the 3rd carb compaired to the other three carbs. #1, 2 and 4 carbs has about 1/8" of the needle showing above the brass piece (the part that has the jet screwed into the end of it) where carb #3 has only about 1/64" of the needle showing.

Is this right? I took some pictures to show what I'm talking about, but the camera died just after taking the pics. I'll post pics here after it recharges.
 
Something is wrong. Stick your finger into the throat of the carb and manually lift the piston. It should lift easily without restriction. With the piston in the upper most position, let go of it and it should slide down with a damped action - and make a solid clunk when it reaches the stop on the bottom. Report back on what you find.
 
The pistons all act the same (slide down slowly) and seat with a "klunk". Here is the picture. The #2 carb is on the left and you can see that about 1/8" of the needle is exposed when it is fully seated (same as #1 and #4). The #3 carb is on the right and the needle is only exposed about 1/64" not nearly as exposed as all other carbs.

carb1.jpg


I took apart both #3 and #4 carbs and can't see why #3 is this way, all parts look the same and both have the same jet size. Both jets are clean as well.

Any help would be appreciated
 
You might want to pull that #3 carb apart and compare the parts to one of the others since something is different. Maybe the slide has been replaced at some point with a similar, but not identical, version?
 
so they PO set the 1,2 and 4 carbs richer than 3 in the needle circuit. to adjust this, you need long reach pliers to take the locking ring off and take the needle out. it sounds like you either have after market needles or the spring in the stock needles broke.
 
Looks to me like the slide is closing farther than the others, why would this be?
 
Last edited:
Needle jets?

Needle jets?

How come the needle jets are sticking up into the lumen of the carb body??:confused:
 
Yeah, the piston on #3 slides further down than all the others for some reason. I don't see why it is doing it myself. I thought maybe since the #3 carb is the carb all others go by, it is set different. Really don't know.
 
Maybe one of the main jets is loose and the jet needle is raised up too high? Not sure but what’s going on, but I am sure something is wrong.
In my opinion, it’s time to pull down the carbs and go through them. Order up an O-ring kit from Robert Barr if they haven’t been done recently.
 
Well I found out why the #3 carb has the slide farther down in the barrel than the others, it is too long. The #3 slide is about 2.5mm longer than the other slides.

Is this right, or has the p.o. put the wrong slide in #3? I placed the #3 slides in the other carbs and it is at the same place as in the #3 carb.

I have a small lathe in the garage and I'm wondering if I should turn the end of the slide down to match the other slides overall lengths. The slide also has a larger bevel around the radius compared to the other slides.

Anyone else have a longer slide in the #3 carb?
 
I don't think you will ever run right with the wrong slide. Find a rack on ebay or see if someone here has an extra slide/carb/rack.
 
I'd bet some PO found a bad diaphragm and swapped in this from a seemingly identical carb.

Maybe post in the Parts Wanted for a slide/diaphragm for that year bike. There's bound to be an eligible organ donor from all the carbs I hear about with ruined threads.

Meanwhile, if you use socket head cap screws on the diaphragm cover (M5 x 12, I think), you can swap in the replacement with the carbs in place on the bike. I'd reassemble the carbs (using the mutant slide), put it back together and give it a quick sync. Ride it until you find the slide you're looking for.
 
Posted in the wanted section yesturday morning and now have a slide/diaphragm coming in the mail today from XenoMorph.

Thanks for the heads-up about the wanted section, can't believe how fast it was!

Hopefully this will settle the high idle speed problem. I also did a washer swap on the main needles and that helped some. I can now get it down to around 1500 idle speed. It also runs much smoother and has more power compaired to before the washer swap (think it was running too lean before, here at ~5,000 ft).
 
Still Need Help!

Still Need Help!

Got the slide in from XenoMorph today (thanks again for the fast shipping!) and compared it to my other slides. It is the same length as the slide in #3 carb. Does anyone have a slide handy that they could measure for me?

The longer slides (the new one and the one in #3 carb) are 55.78 mm in length (measured with calipers) and the shorter slides (in #1,#2 and #4) are 54.55 mm in length. This is measuring from the base of the slide to the top of the plastic piece above the diaphragm.

I'd REALLY like to know what is the correct length for the slide as now I don't know if my #3 slide is correct and all others are wrong or vise versa.
 
I have a brand new slide in a box, P/N 13500-47070, and it measures 55.68mm. This part number is called out for the '80 GS550L. Not sure what's going on with your carbs.
 
Nessism said:
I have a brand new slide in a box, P/N 13500-47070, and it measures 55.68mm. This part number is called out for the '80 GS550L. Not sure what's going on with your carbs.
Click to expand...

Thanks, if that is the case, it looks like I have 3 undersized slides and 2 (with the new one) right sized ones.

XenoMorph said he had 2 left, I emailed him on what size the remaining two were. If they are the right size, I'll try to buy them. I'll then have 4 slides that are the same. Sure wish it was the other way around, this might get expensive!
 
What controls how far down the slide sits into the bore? It must bottom down against something since the spring pushes down.
 
I'm pretty sure that it bottoms out when the metal ring (right under the diaphragm) hits the top of the carb. bore.

I thought about just making a spacer that slides over the slide and fits against that metal ring, but I don't know what that will do to the #3 cylinder under full power (don't know if it will allow full movement of the slide).

The depth of the hole in the top of the slide is also different between my slides. The longer (correct) slide has a deeper hole compared to the other slides.

I may try making a spacer, but I really don't know if that will help. I'd rather get the right slides so that I know that everything is in spec. Just one less thing to troubleshoot when sorting out the system.
 
Well I went ahead and installed the two longer (OEM) slides in #1 and #4 carbs and installed the shorter ones in #3 and #2. The idle can now be adjusted to around 1200-1300.

I also bought the other two slides that XenoMorph had as they were the OEM longer slides, so I'll have all four the right size soon. I'm going to ride it the way I have it until the new slides arrive. It does drive fine and idles better (just took it for a short 20 mile trip).
 
You must log in or register to reply here.
Back
Top