Topic: Will a set of Keihin taken off a 1978 Honda CB550f work correctly on a 74 CB550?

[ryanpsu23]

Will a set of Keihin taken off a 1978 Honda CB550f work correctly on a 1974 CB550 Four?  I wasn't sure if the carbs from that were compatible with a 1974 CB550.
Thanks

[dave500]

theyll work ok.

[TwoTired]

Will a set of Keihin taken off a 1978 Honda CB550f work correctly on a 1974 CB550 Four?  I wasn't sure if the carbs from that were compatible with a 1974 CB550.
Thanks

Yes and no.  The 78 carbs would need rejetting, and the couplers fore and aft are different sizes to accommodate the different carb length and carb "mouth" size.
78 carbs would need the choke knob transferred, too.
The carb bore spacing is different. So, unless you don't mind forcing things into "sorta" place and worrying about air leaks in the couplers, both the intake runners and the air plenum chamber should come from the donor bike, as well.

If you have the will and patience, you can make them work.  It is no slam dunk, though.

Cheers,

[ryanpsu23]

Thanks for the replies guys and for the explanation of the differences I'd be dealing with. I was looking at a set from the '78 on ebay and will wait on a set to come up closer to the 1974 model year.

[TwoTired]

Wait, perhaps I misread that.  In 78, and in the US, there was only the K model with PD carbs.  There was no F model in 78.  The last year of F model was 1977, and the carb style for all Fs was the same as the 74, just the jetting was different.

So, was that a trick question?

[ryanpsu23]

They have it listed as coming from a 1978 F model on ebay. The look of the carbs do make sense with the description you gave of the choke, etc, so I was thinking of just waiting on a set that looked more in line with what I'm seeing stock on the 1974

[ryanpsu23]

here is the ebay link to what I was viewing:
http://www.ebay.com/itm/HONDA-SET-OF-4-VINTAGE-KEIHIN-CARBS-CB-550-CB550-CB550K-/130745950465?pt=Motorcycles_Parts_Accessories&hash=item1e7110e101&vxp=mtr

[TwoTired]

Those are PD carbs.  No factory F model had those.  Only 77-78 CB550K models.  They ought to be stamped PD46_, where the blank space is a letter and would tell you if they were 77 or 78 issue.

[ryanpsu23]

Thanks again for the heads up.