CB 22/23 Vs CB60/61/50/51 Differences

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There are obviously some differences between the normally aspirated CB23 and the turbo charged CB60's. For the purpose of this article the CB23 includes variants CB22, CB24 and the CB60 includes variants CB50, CB51, CB61, The following answers some of more popular queries.

The CB23 has a two stage vacuum advance diaphragm on the distributor while the CB60/61 only the one stage. Both are vacuum operated, plus the CB60 has positive pressure retard.The CB60 model vacuum advances 10° and retards 7.5° (under boost), while the CB23 advances 11°. The centrifugal advance is 10.5° on the CB23 and 13,5 ° for the CB60. Staic timing is 5° for CB23 and 10° for CB60. See dizzy specs here

The CB60 carburetor has a pressurised fuel bowl so that the venturi continues to operate on boost.

The CB60 carburetor does not have a power valve

The secondary throttle release dashpot on the CB60 carburetor is +ve pressure.

The CB60 has a larger secondary venturi neck (CB23 primary 28/18 secondary 32/25mm; CB60 primary 28/18 secondary 32/28mm)

CB60 jets are different : CB23  0.83mm primary, 1.41mm secondary; CB60 XXX mm primary XXX mm secondary

The pistons on the CB60 are noticeably dished for lower compression (CB23 = CR9.5, CB60 = CR8.0).

The oil filter is mated to an oil cooler on the CB60. A bango bolt is also integral of the casting for oil supply to the turbo.

The CB60 has a different alloy casing on the non drive end that includes a flanged port for oil return.

The CB60 has an electric fuel pump in the tank and a manifold pressure pilot operated fuel regulator on the fuel return line. The CB23 has a mechanical pump on the distributor end of the head,

Of course there are the other differences such as a turbocharger, vacuum lines, surge tank, car trim, etc.

See also pics of CB heads