Topic: Emergency Carb Drain Screw Washers!

[DiscoEd]

Hi,
I am trying to get the CB550 fired back up. I've got a couple of bad (leaking) sealing washers on the carb drain screws. The washers that are on there seem kind of conical in shape (maybe they have become that way over time). I would order some, but I hate to wait for them to show up. I was wondering if it would be possible to use a standard o-ring for these? If it is possible to use o-rings does anyone know what size?

I'm also open to hearing any other suggestions that I could try, so that I can get her running without loosing the precious juice?

Regards,
DiscoEd

[csendker]

I went to the local hardware store and picked up 4 new o-rings for my drain plugs.  8mm OD, 6mm ID if I recall correctly, I took a plug and bowl with me and tried a bunch.  I think I jotted it down somewhere, I'll dig for it.  I did ask if they were rated for gas, and the young guy said "Unnn...", but the old guy (it was a real   hardware store) said they were OK.  So far, so good.

[Bob Wessner]

Don't know much about your 550, but I temporarily used some O-rings on the drain screws of my 750. I took a screw with me to the hardware store and sorted through their O-rings to find a good fit. One thing I did notice though on my 750. The underside of the screws had a curved area between the threads and the underside of the head. I imagine this was to center the washers. Don't over-tighten the screws as this will tend to spread the O-rings and possibly lead to splitting them. This was just a temp. job, but it worked fine for several weeks.

[csendker]

My bowls had an annular depression that the o-rings seated into.  That's why I took the bowl too, just to make sure they fit both the screw & the bowl.

[TwoTired]

I don't know what their size is, but they are simple orings when first installed.  I just use the ones that come in the Honda rebuild kit.  If yours are hard and brittle, then so is the oring on the main jet, float bowl valve seat, fuel nipple T orings, etc.  All supplied by the Honda kit.

Maybe the drain screw interface is different from the 750.  However, there is no need to worry about over crushing the correct sized orings on the CB550 bowls.  There is a relief area that accepts the proper sized oring.

Cheers,

[csendker]

I realized that I had some odd-looking drain plugs on mine when I pulled them off to drain the bowls.  They didn't have the big, flat head on the screw and no o-rings at all (didn't leak though).  When I went to reinstall, I used the normal ones off a spare set of carbs, with my new o-rings.

[DiscoEd]

Thank you for all of the great responses! You guys rock!

I guess I'll have to try the trial and error fitment method for now.

TT,
I see your point about the using the kits, but I can't spring the money for the carb kits right now. Hopefully it will run good enough to get me by for a little while till I can get the rebuild kits.

Regards,
DiscoEd

[keiths]

I installed hardware store o-rings 3 years ago and they still work fine.

[DiscoEd]

I think I may have found some that will work. I will post with the size information as soon as I'm sure that they will work without leaking all over.

Regards,
DiscoEd

[techy5025]

The early bowls had flat fiber washers that were superceded by o-rings. In
the process the screw was changed also to one with a bigger diameter and
flat on the back of the head.  Changed at serial number 1070373.
O-ring is 4.47 by 1.78.

Jim

[motorcycleclaude75]

Hi Guys,

How bad would the leaking be if the o-ring was bad?

Just curious.

Claude

[csendker]

Anywhere from the occasional drip to a gusher, depending on how bad it is and how tight you jam the drain plug in.  I had the occassional drip with non-OEM drain plugs and no o-rings at all.  ~$3 later, I have no drips whatsoever, new o-rings and a set of standard drain plugs from my spare carbs.

[Bob Wessner]

The early bowls had flat fiber washers that were superceded by o-rings.

Interesting. Mine (750 K0) are flat aluminum washers. Given the bike's history, or lack of, I have no idea if these were ever an original OEM item or added by the PO.