1980 Carb rebuild question.

[JasonLester]

I found that my carbs were leaking on an off when I first got the bike. I suspected a sticking float and started running Sea Foam in the tank. Unfortunately I had charging issues so I did not get to ride much last year. With all of that fixed I was looking forward to this riding season.

Well now with that time here I find myself with another problem and that is again the leaking carbs. I took them off the bike and took the bowls off and sprayed them out good and reassembled them. That was no big deal. My accelerator pump had a bunch of what looked like gravel in it. I guess corrosion of some sort but it was loose laying in there. I cleaned all that out and reassembled them but didn't take the carbs off the assembly.

I am a little hesitant to do so as I'm afraid of what I may break. or not be able to put back... I'm probably over thinking it but that’s me.

Anyway I hooked the tank back up off the bike to the carbs, and unfortunately they are still leaking. My guess is the tube that the fuel comes in to the carbs on (big ones between the carbs) . They seem loose like there is no seal between the carb body and them. If fuel runs through these like I think it seems wrong.

I didn't buy the 30 dollar a piece rebuild kits so I am wondering if I should have. Also I'm wondering if I can somehow seal these with some gasket maker or something to avoid taking them apart completely...

BTW other than the accelerator pump they looked really good inside.


Also if I need to tear them apart how hard is it to reassemble...I'm just trying to decide if trying to seal the tubes is worth it.


Thanks.
Jason

[Kitsune84]

I'm going to be honest with you, man.
If you don't buy the rebuild kits, you can expect to do an endless number of rebuilds, again and again for leaks as they show up with hardening, shrinking o-rings.

The kits are expensive and hard to find, but If you're going to do it, do it right, and hopefully the only fixes after that are small ones.

That said:
It's not impossible for these carbs to leak from those fuel passageways, esp. if the o-rings have shrunk and the tubes feel loose.

I suppose another possibility is that your float levels are skewed, or your float needles worn and not sealing right and/or the spring in them is sticky and not rebounding correctly.

My #1 recommendation:
Buy the kits, the air cutoff-valves, and maybe an accel pump diaphragm, unless yours is okay still. Either way, it's easy to access, but go with the air cut-off valves because they have a tendency to rot and are damned impossible to get to while the carbs are racked.

Also, get the little tiny bolts for your choke butterflies here:
http://www.boltdepot.com/product.aspx?c ... 19&cd=1366
the phillips' heads just don't cut it anymore after you take them out the first time.
Use a drop of blue loc-tite in the threads on re-assembly.

Either use a clymer's guide or download a service manual .pdf and follow those directions on dismantling your carbs.

Replace o-rings etc as you can. Oil your o-rings lightly on assembly so they don't twist or tear or anything, some of them will fit quite snugly.

Make sure the tops of your floats are about parallel with the gasket mating surface, and while you're at it, (since you're replacing the needle valve anyway) polish that hinge pin so everything rebounds quickly and smoothly.

Remember to blast out your accelerator pump passages, too. They clog REAL easy and you DEFINITELY notice the difference.

I think that's it. Sorry if it's not the news you wanted but I'm a stickler for doing it right the first time. Lord knows I've done my carbs SO many ways the 'quick and easy' way... and had to redo them later because of it.

just wanna save you some misery.

[Kitsune84]

oh and chunky crap in your accel pump could mean you have rust in your tank that is going to mess up your carbs over and over and over again. Try an inline fuel filter, too.

[JasonLester]

I agree that the kits are a good idea. But at 120 to do the carbs I'm still in sticker shock. As for orings other than the big orings that go around the bowls I can get pretty much any oring I want so I haven't seen the need to buy a 120 dollars worth of kits just for orings. I probably have orings here that will be the right size anyway if not I can have them tomorrow. At least most of them....

As for the rust in the tank I already have an inline filter. This wasn't rust. It looked more like corroded aluminium (SP?) Pluse the tank is very clean. I drained it and checked it when I first got it last year.


Oh and this is the 1980 carbs not the 1981's no air cutoff. I think I'll go take a look. Maybe I'll pull them apart (or try) and see. I haven't seen any worn parts yet but if I do I'll order the kits.

[Kitsune84]

I have a 1980 CB650c with PD50 carbs. They have air cutoff valves, they're on the sides, under the plates held down by two phillips screws.

If you REALLY don't want to buy the kits (and I can see why, since the brass parts from keyster suck) you can go with fluorinated rubber (or at least very, very petrochemical resistant rubber) o-ring kits from Harbor Freight, and just buy the float needle valves and float bowl gaskets separately. I don't really see the fiber gaskets in the tops going bad any time soon. The only ones that might be tricky are the ones that cover one of the outlets for the air cutoff valves, and those are actually provided with the valves, so no worries.

[JasonLester]

I'll get Buna-N orings they are fine for fuel.

....

I still haven't decided what to do as I hate to have to do it again. I thank you for the info btw... I'll have to check about the air cutoffs.

Too much to spend money on and not enough cash I guess. Plus I'm itching to ride...

[Volker_P]

Getting out the carbs is a pain due to limited space, so I partly understand your worries.
To get an idea whether there is a quick fix, it would be quite important to know where exactly the carbs (all four?) are leaking. If they are leaking from the central nipple of the floater bowl, maybe this is a needle valve seat problem and may be done with the carbs installed. If fuel pours out between the carbs without floater bowl overflow, you have to get out and to separate the carbs to change the small O-rings.
Only few models really have the air cutoff valves, most just have the covers with nothing behind. Maybe strange but is all right.
I am a bit worried about the gravel in the accelerator pump. I would guess gravel even there would mean your floater bowls would look like a rubbel dump. As they did not, the previous owner might have already cleaned them but also did nothing about the accelerator pump and probably also nothing about the rest of the carbs but sold the bike instead.

[JasonLester]

Volker,

Kind of what I was thinking on the accelerator pump...I was told the carbs had been gone through but its obvious to me the kits weren't used and whoever did it didn't touch the pump. I got this bike from my father in law who got it from another guy. I talked to the last guy it was titled to but it had been passed around a bit so its a bit scetchy of what was done.

The parts look good from what I can look at so far so I am not sure I need to get the kits. I know I probably should but as money is tight everywhere I'm not sure I can justify the cost when I'll mostly just need the orings.

I'm going to seperate the carbs and see what oring I need. I believe thats where the leak is from not the float valve seat. I'll hook it back up and make sure before going much farther. But the gas is coming down off the side of the carb near the accelerator pump...My first thought was it was leaking but I don't believe that is the case now with those fuel delievery tubes feeling as loose as they do.


Anyway thanks for the info. I need to just dive in and pull these apart.

BTW is there a source for any of the brass parts outside buying the kits?

Thanks again everyone for the feedback.

Jason

[JasonLester]

Little bit of an update.

I believe I was worrying they would be more complicated than they are. I seperated them tonight and its really not that big of a deal. Oh and BTW the Orings on the tubes that lead between carbs are shot. I'm going to have to get the smallest one but already have ones to fit the bigger tube.

I pull them apart more tomorrow and see if I need anything else. I know I need a couple of the screws for the choke butterfies (normal to replace as I undestand) but even most of them came out fine. All the brass stuff looks fine... Its a pretty low milage bike so I am not supprised. 12k miles if I remember right.


If I can find a new accelerator pump I may replace that too....I'm sure I can make it right for well under $120 especially sinc eI can get the o-rings free at work

[Volker_P]

...I'm sure I can make it right for well under $120 especially since I can get the o-rings free at work

Yes, this is my favorite proceeding, too.
Don't forget to fix the bolts for the choke butterflies with the metal sheets or/and loctite.
12k miles should not cause wear that asks for replacement. Rather corrosion from standing may play a role. My carbs are >60k and still work fine.

[JasonLester]

other than what little I saw in the accelerator pump I don't see much corrosion...I think I am good once I get the orings in there I've cleaned it up pretty good. Still needs a little work but I ran out of carb cleaner...

Now getting them back together just right might be fun but I'm pretty sure it won't be to bad...


I really need to find my manual....LOL

[arcangel]

Sounds good but make sure you spray cleaner in to the small holes in the carb body they are bad about getting cloged and cause very poor running and the choke to be on all the time for the bike to run.

[Volker_P]

I really need to find my manual....LOL

Meanwhile, thanks to Cosky, you can look up here: http://cosky0.tripod.com/

[jopace]

Hey Jason, I just remounted the carbs for the 3rd time last issue was the no.2 overflowing. few things too note the interconnecting alum tubes are not all the same length. test the carbs off the bike, i used a plastic container to hold the carbs and a lawnmower gas tank first to check for leaks. Don't use the lawnmower gas tank it doesn't exert enough pressure to test correctly, use the actual fuel tank from your bike.
My bowl gaskets were good until I disturbed them so I blue RTV the little grove on the bowl then pressed the gaskets back in ,let dry then put em back on, with the floats right side up prefrably ask me how I know . press the float tangs a good way out then apply light pressure to get the float height back. im back to the inaugural start maybe this time she will fire since im not leaking yet and i got the cam in right this time, but thats another nightmare

[jopace]

update, just sarted the beast, it didn't catch on fire which pleased me, the first try didnt work then i put the off run switch in the run position.
I could'nt stabilize the run after she warmed up, smoked some on the left side recon the rings need breaking in , new motor n all, still leaked later on after i shut it off, out of adjustment and worn float needle I belive but it was nice hearing it run. ill post a video link