"Dipping" carbs....??

[Bladerunner]

Hey Fellas,

Into my second month of GS750 ownership and loving it. Anyway, my bike is a '78 and was taken care of very well during the past 32 years. It runs flawlessly, starts first kick or crank every time, fuels perfectly with crisp throttle response and no stumble anywhere.

Having said that, I have been going over the bike with a fine-tooth-comb making sure everything is tuned properly and any issues addressed while trying to do a little prevention.

I have read several threads about "dipping" the carbs on these machines. Would there be any benefit to me "dipping" my carbs even though the bike runs great? Does this dipping involve complete disassembly of the carbs, or can they just be lowered into a large can of carb cleaning solution for a period of time, removed, drained and re-installed?

I have become so spoiled by modern fuel injection, that my familiarity with carbs is very limited.

Thanks,

Trent

[tkent02]

If it's really working perfectly, don't fvck with it.

[Bladerunner]

don't fvck with it.

Yeah, that's what I thought. Thanks.

Trent

[Khyber]

Bladerunner -

Do your carbs have diaphragms? You can tell if you have a plate on the top of your carbs (which I think all do) held on by screws (or similar). Once you remove the plate (cover), you should be looking down at what will appear to be a rubber cone (or 'sheet,' for lack of a better word). Your carbs should also have cylinder-looking things in the actual carb itself, if you were to peer down the throat. It should move up and down, revealing the main fuel needle when you lift it up. I think these are called 'slider' carbs? I may be wrong, but that's my nickname for them for now until someone sets me straight .

Anyway, these carbs will have a main 'throat' for air to pass through and collect fuel from the main needle or idle jet, etc. But they should also have another, much smaller channel up top of the throat.

I have found a picture on the net with what my (our) carb looks a lot like, and due to the fact that this is my first post on any forum (glee!!) I don't know if it'll show up right, but here goes:




(http://www.teamcalamari.com/pix/20mm/14b.jpg)

Looking into the throat of the carb, we see a large brass-colored 'slider' and attached below the main needle. Mine is actually black plastic, and yours may be as well, however this picture will demonstrate my purpose just fine. That slider should move upward, as to allow more air to pass through, and expose more of the needle. Now, for anyone who may not know exactly how carbs operate, the needle is tapered, meaning it comes to a point like a No.2 Pencil (to put not too fine a point on it, if you'll excuse the pun). The purpose of this is to allow a metered amount of fuel to be sucked out of the bowls. How? The needle fits into a hole. Imagine sticking a pencil into a straw, and trying to flow fluid through it. It shouldn't at all. Now imagine if you pulled the pencil out just slightly, and now fluid flows slowly around the pencil tip. Pull the pencil completely out, and the fluid flows as fast as the straw will allow.

And now back to our point: The upper hole allows vacuum to be drawn on the top of the diaphragms. This negative pressure causes the soft rubber (or similar material) diaphragm to be sucked upwards. The 'Sliders' are attached to the underside of the diaphragm. When the diaphragm gets sucked upward by the negative pressure, it pulls the slider up with it, allowing more air into the carb. And attached to the slider, is the needle, so when the slider moves upward, the needle also comes up and allows more fuel to flow between it and the hole it fits into. Make sense so far? (and if I'm just toootally wrong here, which I admit fully that I may well be, I hope someone will set me straight . I'm pretty sure I'm close, though.)

Because of the major role the diaphragms play in all this, they are, in fact, a critical element of carb functionality. If you tear the material, the negative pressure will just suck air through the tear, and the effect is completely lost - that carb will be forever stuck at 'idle' position (or worse than idle).

Now, the reason for the LENGTHY, lengthy lecture is to point out that not only are the diaphragms important, but they are also very sensitive. It is recommended that such diaphragm carbs are treated VERY carefully when cleaned, as many strong/caustic cleaning agents will just MELT through the diaphragms. So here is what I will tell you that I did:

I bought a can of Chem-Dip as (hopefully) pictured here:

http://ecx.images-amazon.com/images/I/31YRRAQ9Q0L._SL500_AA260_.jpg

This stuff is AMAZING, but is also VERY strong. what I did was, remove the carbs as a whole, remove the bowls, and purchased a small oil drain pan just large enough to span the length of the carbs. I sat the carbs in, without the bowls, and filled the pan with Chem-Dip until the level reached about midway up the carbs. I then left it to soak for a half-hour to an hour. Keep in mind, NOT TO SUBMERGE THE DIAPHRAGMS!

The reason for the pan was, besides not wanting to screw around with any of the linkage and carefully set synchronization and place in the entire unit, was to make sure that the level of the Chem-Dip bath would NOT wash up onto the diaphragms. Take care to put the carbs in, and out of the bucket SLOWLY!! You do NOT want it to splash up onto the diaphragms, lest you run the risk of this miracle stuff to chew through the fragile rubber.


Before I got the Chem-Dip I spent a lot of money and time on cleaning supplies and tore into the carbs. The needles were a light yellow-brass color, and had deposits of nasty gas all over them. I carefully removed them and cleaned them down with brake cleaner (which was an awful idea, in hindsight), and by the time I was finished, the carbs LOOKED very clean and smooth. When I didn't have any success when mounted back on the bike, I went to the Chem-Dip bath, and learned the needle was actually SILVER in color!! Put them back on the bike, and WHAMMO! Started right up like she hadn't been sitting for 3 years!




Some concern was raised by even the FUMES of cleaning chemicals eating the diaphragms. Well, it worked for me, and I only let them sit in the pan for an hour at most, and I'll swear by my personal experience, but that doesn't mean someone can't get themselves into trouble with this stuff. It's VERY effective at stripping anything off metals. Including softer metals, if I read the label correctly. So you actually DON'T want this stuff on anything for too long .


I hope this answers your question, Bladerunner. I think dipping is a great idea if you're careful and patient, even if the bike seems to be running well now, you may unlock an extra 5-10 horsepower!! WHO KNOWS?! And as I stated, all the stuff you would need to clean are on the bottom half, and all I took off was the bowl to allow the Chem-Dip to get at all the goods. I did submerge the bowls completely by themselves as well.


Let us know your feelings and results

[Jagir]

If it's really working perfectly, don't fvck with it.

+1

ride it.

If you want/need to do something, polish the silver parts.

[goggleboy]

if it aint broke.... yep.
im dipping right now and it sucks.
the weather and clouds are moving around while i sit and dip.
enjoy your bike! maybe run seafoam through or something

[Nessism]

The O-rings are sure to be hard and brittle on 30 year old carbs. I would change them now although since the bike is running well, dipping the carbs is unnecessary. Regarding how to do so, there is a rebuild tutorial linked on the GSR home page, in the Garage section - look for VM carb tutorial.

Good luck

[ddaniels]

Ride it for now. When the weather turns bad, get some o-rings and change them out along with the intake boot o-rings. While you have them out, spray some carb cleaner through all the passages. This does not replace dipping if your bike isn't running good, but since yours is, I would think that would be all you should do. Negatory on dipping the whole rack as there are sensitive rubber parts that won't stand up to the solution. After your o-ring change and carb cleaner spray-through, put it all back together, fill the tank with fresh gas and add some Stabil or Seafoam, run it for several minutes to get that stuff into the carbs, and park for the winter.

[Bladerunner]

Wow guys; this forum is the schiznit! Thanks for all of the replies. I can't get over how helpful everyone is around here. Thank you all very much.

I will not "dip" the carbs as I mentioned earlier as the bike is sweet running as-is. But I will heed your advice and replace the o-rings over the winter, and give them a good spray. I had already planned on replacing the carb-to-intake boots as I simply do not trust them at 32 years old.

Come next spring I want my GS to turn heads and also be able to ride to California at a moments notice without any hesitation. I'm amazed at how robust these bikes are for their age and design.

Thanks again.

Trent

[tkent02]

If you are going to pull them off anyway, might as well dip them and do the whole shebang right, it can't hurt.

[koolaid_kid]

tkent02 has a valid point. In order to replace the orings, you have to completely disassemble each carb. At that point, you may as well dip them and do the entire job. Added cost - $20 for the dip and 4 days (soaking each carb 24 hours).

[cowboyup3371]

+1 on what they say...why do it twice?

[BassCliff]

Hi,

Here are a couple of helpful links...

CARB CLEANUP SERIES

EDIT: Oops, that's the wrong procedure for you. Here is a link to the clean up procedure for pre-1980 carbs (VM): VM carburetor rebuild

http://cycleorings.com - Get your complete O-rings set here. Also available are intake boot O-rings and hex fasteners for your carb intake boots. It's usually a good idea to replace those 30 year old intake boots too.

When you're done with that, check out the BENCH SYNC procedure and finally the VACUUM SYNCHRONIZATION procedure.


Thank you for your indulgence,

BassCliff

[ddaniels]

If you are going to pull them off anyway, might as well dip them and do the whole shebang right, it can't hurt.

Good point. Agreed.