®    Carbs Marcus

A set of Honda CB750 race kit Keihin CR carburetors I had the pleasure and honor of resurrecting earlier this year. These belong to Herb Marcus in California.


There were two versions of these carburetors. The originals appeared in a Honda race kit for the CB/CR750. Yoshimura later offered them for the then-current Z1s and similar machines. These are actually Honda carbs, not the Yoshi aftermarket items. The difference is in the idle circuit.

Note the tickler style choke. This view gives off the wet blasted finish nicely also.

Yes, plated socket head screws were used instead of the original unique, proprietary, and quite rare original fasteners. What the heck, Herb is putting them on a Kawasaki anyway!

And yes, that's a Honda CX500 idle speed screw. Same explanation.

Beautiful! Note the 60s-era fuel banjos, freshly re zinc plated. This set also has the longer of the two optional length air horns.

Very unusual linkage. A little car-like. And all it of newly replated. Surprisingly smooth-acting and with a light pull.

Deep drain plugs/main jet access plugs. Zinc plate and polish. Pretty.

Very light carburetors. I don't think they're magnesium, but they are very thin castings and very compact. Delicate.

Worth it to have these just to look at, don't you think? They are gearhead exciting. Another view of the idle speed screw arrangement also.

Lot of attention to detail went into these. For example, as could be expected with 50-year old parts, and parts certainly abused at less than competent hands, nearly all the threads were pulled and had to be steel inserted.

The plater messed up on the top steady bar and it had to be sent back and re-plated. I welded and straightened the bar as well. An odd feature: Note that the whole top steady bar must be removed, including the throttle cables disconnected and 20 screws removed, in order to adjust the slide needles. The needles are of course in quick-change holders as is standard on CRs. But...

The air horns were pretty torn up also. Pliers and chisels had obviously been used on the hook spanner intended notches.

Closer view. The horns were set up on an indexing table in a milling machine and the notches recut.

A gratuitous beauty shot. Don't ya just love it? Voluptuous carbies, these!

Another closeup of the linkage. A part of the bellcrank was damaged and had to be rebuilt. There is a piece of a CBX1000 carburetor in there as part of the repair.

A closeup of the starting tickler. Disassembled, the correct parts replaced some make-do Mikuni pieces, and the tops were plated. Note the very simple float bowl vents, simply holes in the sides of the carburetors.

More user-unfriendly 1960s racing design. The lower carb rack steady plate has to be completely removed in order to remove any of the float bowls.

Some repair was needed here, where the main return spring locating mechanism was heavily molested.

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