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rebuilding carbs
exvalvesetdabbler:
There is no ovality on the needles, which is why I suspect corrosion has had a hand in what happened. Looking at the outside of the tubes there isn't any corrosion/putting that would set off alarm bells, hence why I originally reused them in 2010.
Fortunately the 'come in handy box' delivered and I have 6 good tubes to play with.
Regards
Dave
Oddjob:
I happen to have a bag in front of my keyboard full off all the brass out of a set of 550 carbs. So I thought I'd try this and see what the result was.
Completely different. None of the needles went down fully, in fact they stopped well before the grooves, plus even in that position they were really protruding past the end of the emulsion tubes. It seems the 500/550 needles are considerably longer than the 400s. You'd expect they'd be similar, same style of carb so why are the 400 needles so short? How do they interact with the main jet when they don't protrude past the end of the tube. Have you checked the number stamped on them to see if they are standard? maybe someone swapped them in the past out of a different Honda.
exvalvesetdabbler:
I have about 8 of them, the good 4 were run in the bike when diagnosing the original problem. I then bought 4 honda needle sets (they were reasonably priced at that time)and installed them. They were all the same length/taper. The good 4 came from a wrecked bike that I bought for spares in 1987. The carbs hadn't been messed with apart from chewed up drain screws.
I can't see any keihin logo on either the tubes or needles. The needles have 18234 etched around the top just below the circlip groove.
Regards
Dave
exvalvesetdabbler:
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Looking at Keyster documentation they have 18234 annotated next to their D22-S(standard) needle which might be a clue.
Regards
Dave
Oddjob:
On the web they reckon the standard needles as fitted by Honda were marked D22. As in all things that's subject to be wrong. Shame I can't find the same tables the 500/550 has for all there markings.
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