cb750 carbs on a cb77

bfd402 · Post by **bfd402** » Wed Dec 06, 2006 7:52 am

Does anyone have experience adapting the cb750 K0 to a cb77 head? These are a spigot mount and much larger than the stock items.

This is being mounted on a cb77 race bike.
thanks
bfd

Hahnda · Post by **Hahnda** » Wed Dec 06, 2006 9:40 am

Saw these on ebay
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These are modified K0 CB750 Keihin carbs that were going to be installed on a 305 Superhawk racer. The K0 carbs were the early models with separate cables into each carb. The vintage racers bore these carbs 2mm over and adapt the CB77 linkage to the carbs. The bore is 31mm in height and the slide is 26mm. The set includes a used split throttle cable (one cable into a splitter, two cables to carbs) and the choke linkage. It also includes the gas line connections to link the carbs. Overall height of the carb from top of cable adjuster to bottom of brass overflow tube is 6.5 inches. I can't tell you the difference in the bore height vs standard carbs because I don't have any standard carbs to compare. The carbs will require modification or a special intake manifold to allow them to bolt to a 305 head because there is a spigot forward of the bolt flange that stock carbs don't have and the bolt spacing on the flanges are different.

The rubber boots are ram air/velocity stacks for the air intake side of the carbs.The person I bought these from is a successful AHMRA racer and a very good mechanic.

http://search.ebay.com/120053443741

bfd402 · Post by **bfd402** » Wed Dec 06, 2006 12:05 pm

Hahnda
those are the very carbs that prompted my post. I can cut off the spigot or perhaps come up with some other type of rubber mount like on a later CB model but was wondering if someone has already done it.
thanks
bfd

Hahnda · Post by **Hahnda** » Wed Dec 06, 2006 12:35 pm

I don't know much about it. I guess the first thing would be to find out if the hole spacing is the same or close. Another possibility would be to machine the head to accept those spigots. That is if there is enough material there to machine.

I wonder what other carb possibilities are out there.

bfd402 · Post by **bfd402** » Wed Dec 06, 2006 12:44 pm

I didn't spend alot of time with it last night. The stud spacing in the head is a little bit different but the difference between the i.d. of the spigot and the intake port is huge. A little dremel work is not going to do the trick on this one.

Any help is appreciated. I'll post what I figured out when I get there
bfd

Hahnda · Post by **Hahnda** » Wed Dec 06, 2006 12:47 pm

Stupid me. I just realized that you actually bought those carbs. Very interested in what you find out.

Hahnda · Post by **Hahnda** » Thu Dec 07, 2006 10:40 am

One thing to keep in mind, even if you cut the spigots off you will still have to do some work to the head. Large diameter carb going direct to a small diameter in the head is really going to disrupt the fuel/air flow.