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That #@*$% accelerator pump! I may have found a cure.

fivestring

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I have a '78 SOHC with the PD42 carbs. I purchased four rebuild kits that included the bowl rubber gasket, needle and some o rings. I also purchased a new accelerator pump which came with a new spring and a rubber dust boot. None of the kits I got included the tiny o ring that goes between the bowl and carb body to seal the passage where the accelerator pump squirts gas up into the carb body. And my carbs were missing this little seal when I opened them up (bike was not running when I bought it). Here's a good picture of this elusive little critter, although it is from a Honda CBX carb:

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I tried to find a replacement o ring from my collection. None seemed to work, either they were too thick and closed off the passage so no gas came out the tubes in each carb venturi or my attempt at using silicone sealer would fail and allow the gas to leak right back into the bowl or leak outside the carb bowl. No matter what I used, I was not getting the little stream of fuel that is so necessary to acceleration from idle.

After removing, installing, removing, and bench testing several times, I was at wit's end. I thought, "why didn't they just use a paper type gasket to seal everything like my Mikunis do?" So I looked around and found an old paper-type gasket from the top cover of these Kei Hin carbs. I cut a small circular gasket from the largest screw hole in that gasket, put a tiny bit of sealer on it and put it together, sandwiching this new gasket in place of the missing little o ring seal between bowl and body. I used the regular rubber bowl gasket, I didn't change anything there.

So far, with bench testing, it seems to be doing the trick. I tightened the bowl screws a little extra snug to be sure the bowl would not leak. I'm finally getting four tiny streams of gas with each throttle movement.

I'll update once the carbs are mounted and working properly, or not.
 
It should work as long as it got a little bit of clamping force on it. I ended up cutting a thicker oring down a bit to make it thinner to get me by for now.
 
Well, so far so good. I got the carbs mounted on the bike and spent most of the day getting them sync'ed but they are finally adjusted. Here's a couple pictures of the gasket I made.

2013-02-10101848.jpg


2013-02-10101923.jpg
 
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Good job, That little O-ring has screwed a lot of people, It seems a lot people reassemble their carbs and forget to put that ring back in. Just like when they change the oil filter they must throw out the washer that goes between the spring and the filter. I've seen this so many times over the years of wrenching on these bikes. It's refreshing to see that other people think up good solutions!
 
speaking of the washer that gets thrown out with the oil when removing the oil filter.....I purchased a bike and it appears that there was not one when I removed the filter. no leaks. Any place like Home depot that I can find one close enough to use? there was also no washer on the drain plug. Sloppy work...makes me wonder about the rest of the bike:confused:

1980 cb900c custom in Florida
 
speaking of the washer that gets thrown out with the oil when removing the oil filter.....I purchased a bike and it appears that there was not one when I removed the filter. no leaks. Any place like Home depot that I can find one close enough to use? there was also no washer on the drain plug. Sloppy work...makes me wonder about the rest of the bike:confused:

1980 cb900c custom in Florida
Renee, this is a ten year old thread. You should start a new one.
To answer your question, you can probably order one from Honda still. If not, determine the max width the washer can be, bring your bolt to the hardware store and start looking. You can probably find one.
 
Yes honda still has them, it is a very thin washer, all it does is keeps the spring from rubbing into the rubber on the oil filter element, I have seen and have run them without the washer if I lost or didnt have one.
 
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