Topic: Which Keihin racing carb for CB500K?

[roach374]

So I'm bored in lockdown, and looking for something to do. Why not "upgrade" the perfectly functional, stock carbs on my '72 CB500K with some Keihin racing carbs?

Opinion seems to be divided, however, on whether the CR26 or the CR29 are the appropriate size to fit (DCC has both), and I'm too lazy to pull the carbs off just to measure the manifold / intake size.

Has anyone done this before? What's the right size to use?

[calj737]

Definitely 26s.

[DaveBarbier]

Out of the two, yes definitely the 26’s. I have them on my 674cc build. You’ll never get the 29’s to work right unless you only stay in or over like the 8k rpm range.

That being said, I would bet you’ll notice zero increase in power. And if you don’t tune it with a dyno, you’ll probably loose power. I would personally go with a cam before changing out the carbs. Or maybe a big bore kit. As they say, there’s no replacement for displacement.