Topic: Carb Bowl Drain Plug WASHER?

[jakec]

Is there meant to be a washer on the drain plug on round top carbs?

I have #2 carb leaking from the drain plug and I was going to shop for new O rings, and CMSNL says that there is also a washer in the fiche. I haven't seen this for any other hondas?

Sidenote, does anyone know the O ring size for the drain screw on round top carbs?

[HondaMan]

Is there meant to be a washer on the drain plug on round top carbs?

I have #2 carb leaking from the drain plug and I was going to shop for new O rings, and CMSNL says that there is also a washer in the fiche. I haven't seen this for any other hondas?

Sidenote, does anyone know the O ring size for the drain screw on round top carbs?

The O-ring for those with the big-head brass screw is 1.6x4.7 or 1.6x4.8mm.
The early carbs from the K0 bikes had a separate, soft aluminum washer instead, and they have a smaller head (and are silver colored, not brass). The end of the K0 carbs had this same screw-washer, but in brass. There's not many of those out there.

[jakec]

My round top carbs are off of a 1972 so a K2? Their fiche shows washers.. actually it shoes two items as #52, one washer and one O ring. I guess O ring is correct. (#52 bottom right)



Thank you for the O ring dimensions.

[BenelliSEI]

Jakec...... vintage CB750.com sells the screws, for all years, complete with “0” rings. Or, the rings can be purchased separately.

[seanbarney41]

be aware that float bowls, and even entire carb racks got switched ALOT over the years...so be sure you know what you have...I think k1/7a use a different size drain screw and o-ring(smaller) than later years (larger)

[ekpent]

 If I remember correctly I have a bag of 7/32 o-rings I use for the drain screws on 550's and 750's.

[jakec]

I placed me order at the O ring store per the sizes that Mark gave. The O ring store is great.

[ekpent]

 I ran across the 7/32 size while doing some 500 and 550's awhile back using this faq.Sizes listed worked good for jets etc. if anybody runs across this and been using the 7/32 on drain plugs since on my 750's. Reply #9 - http://forums.sohc4.net/index.php/topic,5410.0.html  Luckily not much rubber in round top carbs and they are pleasant to work on compared to some others 

[jakec]

I shuffled my drain plugs around today and the same carb was leaking. Definitely through the plug, not the drain, it is fairly obvious after watching it. I'm wondering, once I get the new O rings, if it isn't fixed, is it ok to use a dab of gasket sealer on the threads? Anyone done that before?

[HondaMan]

I shuffled my drain plugs around today and the same carb was leaking. Definitely through the plug, not the drain, it is fairly obvious after watching it. I'm wondering, once I get the new O rings, if it isn't fixed, is it ok to use a dab of gasket sealer on the threads? Anyone done that before?

It will likely dissolve and end up stuck in the jets. I don't think it would be a good plan?

[754]

Is your overflow tube cracked ?

[jakec]

It’s not coming out of the overflow tube, it’s coming out of the screw.. the screw is way above the overflow tube and gas if forming droplets on the screw. I think I have gas resistant sealer, I was thinking about putting a tiny dab on the O ring? Maybe? But first i’ll Just check with new O rings to see if that fixes it.

[alacrity]

I would look closely at the threads into which the drain plug screws. If those have been screwed up (no pun intended), you'll get leaks... even with a new oring.

I shuffled my drain plugs around today and the same carb was leaking. Definitely through the plug, not the drain, it is fairly obvious after watching it. I'm wondering, once I get the new O rings, if it isn't fixed, is it ok to use a dab of gasket sealer on the threads? Anyone done that before?

[The Lone Builder]

If it's the screw, how about some PTFE (plumbers) tape around the threads? It's both petrol and oil resistant and I have used it on my brake calliper bleed crew to good effect.

[ekpent]

 You could goop up the threads if a new o-ring doesn't work with a product called Seal-All but I doubt you would ever get it out again. Great stuff. I have used it inside carbs and other fuel related places and even fixed the sole and glued it back together on my work boots. Its a miracle goop I tell ya !
  Wonder if the bowl has a tiny crack somewhere around that screw housing.

[jakec]

I have yellow plumbers tape (for petcock) that seal-all product as well (but not sure if it's gas-resistant)? Seems I have 3 options!

[HondaMan]

I have seen these bowls with a cracked or corroded drain tube that weeped fuel out the bottom: it creeps along the bowl to the bottom of the srew, then drips.
To  see if yours is doing this, apply some sealnat around the outside of the drain tube and see if it stops. Another bowl is the cure: there are "left" and "right" bowls.

[jakec]

It is a #2. Hm might be a tough part to find... I once fixed a leaky drain tube by soldering.