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carb overflow, high idle rpm

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borissytch

carb overflow, high idle rpm

Hi,
I put my CB750SC '83 back on the road two days ago. First time since I bought it.
Just passed the mechanical inspection and noticed - the overflow tube from one of the carbs is leaking when the bike is hot. And the idling is 2000-2200 rpm.
I have the rust in the tank problem. I put the inline filter. So far I made less than 50 km.
I don't think I would be able to clean the carbs myself (if that's the problem), but before taking it to the mechanic I would appreciate any advice, directions to go, steps to follow, temporally measures etc.... Maybe I could start from something simple myself.

thanks!

Honda CB750SC Nighthawk '83

jcarroll

Re: carb overflow, high idle rpm

I have had the same problem. Mine was just a sticking float. Tap on the side of the suspect bowl with a screwdriver handle or something similar for temporary. Run Sea Foam through it can help(did for me), or pull the bowl off and clean it out if all else fails.

TOOLS1

Re: carb overflow, high idle rpm

Administrator

In reply to this post by borissytch

The high idle could be a cable/linkage sticking, a vacuum leak, or carbs out of sync.
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1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
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shinyribs

Re: carb overflow, high idle rpm

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I got a bad load of gas in my '80 lately and now have dirt in my carbs

All four of them will overflow at random intervals. When one of them starts acting up and overflowing the idle gets higher where that extra fuel is finding it's way in to the engine. IMO,I'd say the two issue are related and the result of sticking float needles (dirt) or incorrect float height setting. I'd start there.

Clean carbs are happy carbs!