Topic: '77 CB550K Carbs

[mvdubb]

Hello,
My son and I just bought a 1977 550k to learn/build a cafe racer. Bike isn't running. Carbs are off. Carbs are KEIHIN 087A's, and i havent seen that callout anywhere. Im not even sure these are correct for this bike. Breif searching hasn't revealed much info on rebuild proceedure. Any ideas on where to start?
MV
 

[mvdubb]

ok...stripped the bike down last night. stamp on the case say the motor is a 500 not 550. obviously not original motor. Are the 87's the carbs for a 500?
MV
 

[bwaller]

Those 87's were for a 550K with four pipes. They'll work fine but be prepared to fine tune according to what exhaust and intake filter is included with the bike. Otherwise if everything is stock check what jetting a 500 used, sorry I don't have that info in my head.  Check out the carb FAQ section, it should be easily available.

Welcome aboard. 

[TwoTired]

The 087a carb stamp was used on 1976 CB550K engines.
The number is in reference to the internal setup as the carbs came from the factory.  Several setups were applied toward the same style of carb body.  There is something inside, slow jet, pilot screw, emulsion tubes, main jet or slide needle size/taper, that is different among the different set up numbers.
Of course, the numbers mean nothing once someone has changed internal components/adjustments.

Original carbs for the CB500 were 627 either (A or B).  These will be correct if your cylinder displacement is still 498cc, stock cam, with stock air filter and exhaust arrangement.  Change any of these items, and factory book adjustments and setting for the carbs no longer apply.  If you intend to make a "cafe racer", those "looks oriented" changes are actually engineering changes, and you will have to develop your own program to determine the proper carb settings for the changes you intend to make.
Avail yourself of an engine Dynamometer, or learn to read spark plugs and use a test track to find the new carb settings appropriate to your engineering changes.

Cheers,

[geminimotors]

Woohoo for the search function! Don't intend to hijack, and it's kind of OT: Where are the numbers on the 500/550 Keihin carbs?

[TwoTired]

On each individual carb mount flange, top right.

Edit:
The thread title deceives.  A 77 CB550K had PD carbs from the factory.  The bike in this thread is a hybrid with earlier 76 carbs grafted on.  Number locations and details are quite different between these two carb types.

Cheers,