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Discussion Starter · #1 ·
Hi!

Newbie here. I'm cleaning the carbs on my 1980 CB650c that's been sitting for years. They aren't really gunky, but are a bit yellowish-orange and gritty from the gas going bad, I guess.

I've done some research to prep for this but can't find a solid guide to the Keihin PD50 carbs. It seems like you can't access the slide/diaphragm except from a side panel that looks impossible to access unless you separate each carb. Is that accurate?

And can I clean off the pieces with rubber and the floats with gas? They're a bit crusty. Or something else? Read that a quick blast of carb cleaner and then dry with air hose is ok but... I don't want to make things worse than they are!

Thanks!
 

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Hi Janasonic,

Everything I'm seeing about your PD50 carbs is very very similar to the PD42s on my 750F - if it's different on yours let me know.

You don't have diaphrams - your slides are directly controlled by the throttle cable, and you can remove them w/o separating the carbs. You have to open up the top cover the the carb, loose a set screw, and unhook a spring - the actuating arm will swing out of the way and you can pull the slide out with the needle.

Separating the carbs isn't a bad thing once you get the shaft cleaned up - rust and gunk here will make it a bit difficult.

 

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Thanks again to Bike Bandit.

 

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We've pretty much got the same bike. Mine is Honda CB 650C. (Not sure exactly what the Custom indicates.) Mine was sitting for a while too-- you made need to replace the rear shocks-- I did. But since you're tackling the carbs, you're probably quite mechanically-inclined, so that shocks are small potatoes to you ;-)
 

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Discussion Starter · #6 ·
I'm no mechanic but I try to fix stuff my self if I can! Plus I have some more knowledgeable people around me to help.

I think my shocks are ok... but what was the sign you needed to change yours?

I think the Custom indicates different wheels - the standard had spokes - but other than that I'm not sure.

The carbs ended up being ok, though 2 of the floats didn't seem springy enough to me, despite cleaning them and the little rail thingy they sit on. I got the bike running yesterday and it's a bit rough, doesn't idle on its own... I think I will have someone else handle the tuning.
 
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