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Mike's CB550 Project
Mike_Berkshire:
--- Quote from: Oddjob on March 16, 2025, 01:08:40 PM ---069a carbs are for a CB550F not a CB500K Ted, as I'm sure you know. a 500K made for the UK should be wearing 627B carbs. The 069a carbs have 4 slots on their needles and it runs at 2nd from top as standard IIRC, the problems here sound like flooding to me, if you can smell petrol there's something wrong. Flooding will cause it to run really rich, hence the black plugs, it's like the engine is running on fast idle setting on a car with auto choke.
As these bikes get older we don't know what's been done to them before we bought it, it may no longer have the same brassware it was made with, a lot of people tended to think they'd be better replacing it with stuff like Keysters etc thinking it was wearing etc, worst thing they could have done IMO. The next owner then has to suffer that mistake and a lot move the bike on because it's not running as it should and they don't know why.
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All 4 carbs on my bike are stamped 087A - its a US import 1976 K2 CB550
Oddjob:
Yeah, different markets got different carbs, 087a sounds right for the states. You checked if it still has Keihin brass? They’ll be marked with a stylised K if they are.
Oddjob:
--- Quote from: DomP on March 16, 2025, 01:25:37 PM ---Mines an F Ken on 069a carbs with all original jets etc (some bits supplied by you to replace damaged items) I've adjusted the floats to the specified 21mm? from memory, it will definitely start happily with no choke whatsoever even in cooler weather.
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If it starts from cold with no choke that’s usually indicative of it running too rich Dom. Seem to recall it’s 22mm not 21 btw.
It could be aftermarket float needle and seats, renowned for not sealing properly.
DomP:
All jets, needles etc are the correct size with the Keihin 'K' stamped on them. I wonder if it's a blocked passage but they all appeared to be clear.
Mike_Berkshire:
--- Quote from: Oddjob on March 16, 2025, 05:25:27 PM ---Yeah, different markets got different carbs, 087a sounds right for the states. You checked if it still has Keihin brass? They’ll be marked with a stylised K if they are.
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all brassware is kosher. I did swap out the main jets as they were mixed sizes - Julie let me have some original main jets in the right size. I have replacement slow jets also from Julie and in original Honda packaging. New Viton rubber throughout.
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