Motorcycle Repair: CL77 engine questions, intake ports, air vent

Question
Hi Bill, I am restoring a 1967 Honda CL77 and have finally gotten to the engine. I have some questions I'm hoping you'll be able the help me with. I have three engines that I am taking the best of to build one. Interestingly, two of the heads have the air vents below the intake ports and one does not. The engine number that this head came off of is CL77E-1045191. The casting letters are H J while the other two heads are F and T respectively. Was this a later model head that did not have vents? Which head should I use for my project engine? Last question, will CA77 pistons interchange with CL/CB pistons? The CA pistons seem to be more readily available. What are the differences? Thanks for your help on this. Terry  

Answer
Terry, Honda made a number of changes on the 1967 CB and CLs, including removal of the air vent passages in the head and deletion of the crossover tube for the fuel tank and petcock, to name a couple.

The air vents were deleted at CL77E-1038129. Changes were made to the main bearing locating pins, transmission and crankshaft splines, as well, so you have to be VERY careful when you start mixing and matching engine parts from different years.

CA pistons will work fine in the CL motors. The crown has a little different shape and height.

I have written extensive restoration guides for the chassis and engines, available on CDROM.  Check my website for details.   

Bill Silver www.vintagehonda.com