Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: Harold 400/4 on September 28, 2025, 06:14:39 PM
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Hi all. I’ve got my PD46A carbs in bits, as I had a fuel leak which turned out to be hardened O rings on the fuel supply tubes between the carbs.
Thought I’d give the jets etc a clean up while I had them apart. Got the push fit slow jets out and they are #42 whereas the manual suggest they should be #38. I have seen some comments that the K3 did in fact have #42 jets from the factory.
I'm running standard pipes and air filter etc, and bike ran OK before the fuel leak started, although it was always a bit of a pain to start.
Is there any point in putting in #38 jets instead of the existing #42??
Any advice gratefully received.
Many thanks. Harold.
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I had a K3 but never noted down the pilot jet, but I have a chart on the carbs of all the 500/550s that I downloaded from either this site or the US one and that states a 42 as standard.
But you are right that the manual states a 38 and strangely a 42 for the 500K3 that I think was sold in Europe. But Honda manuals do have quite a few mistakes.
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I had a late US K3 that had pd46B carbs but never noted down the pilot jet, but I have a chart on the carbs of all the 500/550s that I downloaded from either this site or the US one and that states a 42 as standard.
But you are right that the manual states a 38 and strangely a 42 for the 500K3 that I think was sold in Europe. But Honda manuals do have quite a few mistakes.
I wouldn't worry.
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First problem would be finding different jets as parts for PD carbs are few and far between, secondly if it ran fine before it should be ok after, where did you find the O rings from as i dont think they are listed as a spare and i dont remember seeing kits for the pd carbs only the early style
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Thanks for the replies. Having read how tricky it was to get the push fit jets out, I thought it was pretty likely I’d damage them getting them out, so I’ve got a new set coming from Sirius in Canada. They are #38s.
As it happens, I used some Plusgas, put some fuel pipe over the jets and they came out fairly easily with some pliers with no damage.
I agree with you guys in that if it ran OK before with the #42s it should be fine. The jets I have taken out are pretty mucky so a good clean should improve things.
I got the O rings size from a previous post on here, and N Julie supplied them (Viton). Thanks NJ 👍
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I installed 45’s just to improve cold starting and lower range running, made a big difference. It was 42’s that were fitted. Definately wouldn’t have improved downsizing.
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Knowing the K3's cold start behaviour all too well, my choice would be the #42 jets... minimum!