1980 GS850G Carbs

[Anonymous]

New I am. Thanks for the heads up. The last thing I want to do is a trial and error set-up.

Cragar 8)

[Don Lobacz]

Ebay item# 2425079890 is a set of GS650 carbs and they are the same carb bodies as yours (I checked the fiche and made the switch once myself). The spacing is different so you will have to move the bodies over to your mounting bars and you may have to switch some jets. Those mixture screws are aluminum and that is why they self destruct so easily. If they won't come out after heat is applied then it is best to leave them in place. You can do a decent job of cleaning the buildup on the tip by shooting a bunch of gumout up the hole where the tip comes out.

[Anonymous]

Don,

I just did start taking a motorcycle/ATV repair course and am not too far into the program. So my abilities are a little on the slim side. Well, maybe not my abilities, but I don't have a lot invested in my knowledge bank just yet. How hard is it to do what you've explained?

As far as the mixture screws (so I know better next time), is it possible these things are locked in place using some sort of adhesive? I never would have imagined they'd be so hard to get out. If they are, perhaps I should have left them alone. I thought they were supposed to be easy to adjust.

Cragar 8)

[KEITH KRAUSE]

Don,

I just did start taking a motorcycle/ATV repair course and am not too far into the program. So my abilities are a little on the slim side. Well, maybe not my abilities, but I don't have a lot invested in my knowledge bank just yet. How hard is it to do what you've explained?

As far as the mixture screws (so I know better next time), is it possible these things are locked in place using some sort of adhesive? I never would have imagined they'd be so hard to get out. If they are, perhaps I should have left them alone. I thought they were supposed to be easy to adjust.

Cragar 8)

The mixture screws have a coating of sealant applied at the factory. It's their attempt to stop you from tampering with them(emission regulations.) Some have more sealant than others,so some are more stuck than others. It puts us in a bad situation,you have to push down so hard to try to make the screw come up. I stripped the head off one once,but have been lucky since. If I am working on a screw that has never been moved or looks like it's tight,I take a toothpick and clean away all the old sealant I can. The sealant is usually the thickest near the top of threads. I spray a shot of carb cleaner at it and let it soften up the sealant I can't reach. Then I put a drop of 3-1 oil or other lube in there and let that sit a bit. Then I shoot it with carb spray or contact cleaner to get rid of any lube and left over sealant. I take my BEST fitting screwdriver and give it a decent wack with some pliers, just to jar the screw,not too hard. I then turn the screw IN slowly until it bottoms. Now I can clean up the exposed threads and then turn the screw back out where I want it. After I butchered that first screw, this has worked for me. You do have to have a very good fitting driver. I think some people make the mistake of trying to turn the screws OUT first. This usually just makes the threads run into the thickest part of the sealant and the threads get gummed up big time.

[Anonymous]

It's a bit too late to help now, but I had read a tip a long time ago, that once you remove the plugs covering the screws, to spray some liquid wrench on them before attempting to turn them. I did this on my 850, and the screws turned easily, (after not being touched since the factory set them almost 20 years ago).

[Anonymous]

I think some people make the mistake of trying to turn the screws OUT first. This usually just makes the threads run into the thickest part of the sealant and the threads get gummed up big time.

Hmm. EXACTLY what I did....and it makes sense when you say the sealant is thickest toward the top of the threads. There's a definite demarkation line between the bottom and top of the threads on the screw I DID get out.

And thanks for the tip, Gary. Actually, I had let them soak in WD40 for two days prior to attempting the removal. Figured it couldn't hurt.....but, in the end, didn't really help all that much either given the fact that the heads were already chewed up.

Here's what I'm going to try....

If the screws are sealed at the factory, then their current position can't be bad. After meditating on this for a few days, I don't really think I did so much damage to carb#1 that I need to render it unusable. I didn't even get past the screw head with the drilling and I wasn't able to move it either up or down, so it's still in it's original location....and upon looking at it through a very powerful microscope here at work (used by our tribology lab for bearing investigation), I can even see the tip of the air screw. It's a little dark, but should get cleaned when I dip the carbs (and follow through with carb spray through the tiny hole). I'm going to go forward with the cleaning/rebuilding process in hopes that everything will be okay. However, if in the end it's not, I haven't lost anything. Any parts that get new o-rings will easily transfer to the replacement carbs (given the fact I find direct replacements).

So there you have it. My hopes are a little higher than they were on Wednesday. I feel good about going forward and am crossing my fingers for when I start the actual rebuild process (probably months away) that everything will run as it should. If not, I'll go through all the checks and balances to make sure there aren't other issues at hand.

Thanks for your help guys. I KNOW I'll be on here more and more in the future with more and more questions to be answered.....and I appreciate your willingness to help even the newest of newbies.

Cragar 8)

[Don Lobacz]

Don't 'dip' the carbs: the rubber and plastic pieces inside may be eaten away. Also, don't disassemble them more than you need to. Clean up the precision metering pieces (pull and dip jets). Spray out passages with gumout and compressed air. Manually clean the float needle and seat and check the tightness of the o-ring around the seat. When you have the float seats out, spray gumout into the main fuel inlet follow by compressed air - this will remove loose dirt particles that can stick under a seat and cause a fuel overflow. Visually check the metering needle in the carb throat for varnish buildup and scrub it with gumout and an old toothbrush as needed. Gently blow compressed air into the slot on the top of the rear carb throat to make sure that the slides are rising properly. Scrub varnish from all interior bowl surfaces. Reassemble carefully.

[Anonymous]

I'm doing a complete teardown and rebuild of each carb as described in the article on the home page. This bike has 44,000 miles on it. In addition, the carbs are so gummed up from sitting for a few years with old fuel in them that I believe soaking is going to be mandatory. I've already found at least one o-ring that's completey broken in two and the remainder seem so hard/brittle that I believe replacements are required.

Don't disassemble and dip?

I don't understand. Is this not recommended? I've interacted with others on this board that actually suggest it per the article mentioned above. Step-by-step, the article is extremely thorough.

Cragar 8)

[KEITH KRAUSE]

If you did'nt move the screw( a little would'nt matter much anyways) and you're not going to ever re-jet for future mod's, then you'll be fine. If you ended up with some used carbs or larger carbs, it could be a pain. And I think what Don meant by not dipping the carbs, was don't do anything that would damage the rubber parts. Some people literally take the entire carb in one piece or maybe they just take off the bowls and let the whole thing sit in carb cleaner or other powerful cleaner. This can make even good o-rings,etc, turn brittle. I take every single part out and clean with regular solvent and then rinse it with good old gasoline. I do use carb cleaner with a tube to get into all passages, it works better, but even the metal parts I quickly rinse with gas.
As a side tip: if all 4 carbs are taken apart at once, do not mistakingly mix up the float valves and seats. Each valve and seat wear as a matched set, so keep them the way they were in the bike. This can also apply to the needle jet and its jet needle. I'm not as familiar with your 'CV' carbs as I am 'VM's, but that's one tip that matters. Sometimes I forget about the differences in carb design,such as,when I told you about the sealant/coating they put on the screws. MY screws are not capped,so they put a lot of that stuff on. Your carbs are capped,so I don't think they put as much on, or did they? Anyways, good luck on the bike AND your bike mechanic course!. KK.

[Anonymous]

Great tips. Thanks Keith!

In regards to cleaning/rebuilding the carbs, one at a time is my philosophy.....definitely don't want to mix any parts. The only reason I mentioned removing all four air screws was due to the problem I had with the first one. No other parts on carbs 2, 3, and 4 were removed.

There were no caps on my air screw bosses, so I'm not sure if they were EVER included.

Thanks for your help.

Cragar 8)

[Anonymous]

GS850 Carbs

I've run into the same problem. Generally, you can just ignore the idle adjustment screws, when they are frozen or so banged up you can't adjust them or get them out, clean and adjust the carbs around them, synchronize them, and they work just fine. The idle air adjustment just isn't that sensitive.