Combat 72,
To actually answer a couple of the questions you asked; There are several different types of head for both Commandos and earlier models. the Atlas and G15 heads come in two basic formats one to accomodate a spigott or liner that sticks out of the top of the barrell, the heads for these have a corresponding recess machined around the perimeter of the combustion chamber, the later models do not have the spigott recess but both heads have smaller diameter holes for the 4 mounting bolts on either side of the spark plug holes, these can easily be machined out for The bigger diameter Commando bolts. Likewise a non Commando 750 barrell can be mechined and tapped to accept Commando bolts as the spacing is the same.
Regarding frames, the earlier frames from the original pre 70s models have a different centre stand arrangement with the stand mounted to a cross tube under the gearbox, whereas the later frames have the stand mounted to the gearbox carrier assembly and a cross tube near the front under the engine, the stands are not the same neither is the mounting or stand for the side stand. The triple clamps for each frame is completely different and are not interchangeable without modification and machining of the frame at the steering head. The later 750s and 850 frames and triple clamps have a different frame rake angle and can be used in one configuration but not in the other - I forget which but think that you cannot use 850 triple clamps in a 750 frame although the other way round is OK.
There are many subtle differences in oil tanks, battery trays, hubs, mudguards etc that might make them unsuitable for use with your particular collection of parts, so a detailed knowledge of Commandos is useful if not vital in building something out of a collection of parts.
I would echo what others have said about trying to start with some kind of project that is at least partially complete, if you have matching frame engine and gearbox numbers this would be a good start although finacial considerations are important. i think if you keep your eyes open you might be able to locate something partially complete for the same price as an engine on e-Bay.
Good luck with your quest, a set of triple clamps is a fine basis for a new project!
To actually answer a couple of the questions you asked; There are several different types of head for both Commandos and earlier models. the Atlas and G15 heads come in two basic formats one to accomodate a spigott or liner that sticks out of the top of the barrell, the heads for these have a corresponding recess machined around the perimeter of the combustion chamber, the later models do not have the spigott recess but both heads have smaller diameter holes for the 4 mounting bolts on either side of the spark plug holes, these can easily be machined out for The bigger diameter Commando bolts. Likewise a non Commando 750 barrell can be mechined and tapped to accept Commando bolts as the spacing is the same.
Regarding frames, the earlier frames from the original pre 70s models have a different centre stand arrangement with the stand mounted to a cross tube under the gearbox, whereas the later frames have the stand mounted to the gearbox carrier assembly and a cross tube near the front under the engine, the stands are not the same neither is the mounting or stand for the side stand. The triple clamps for each frame is completely different and are not interchangeable without modification and machining of the frame at the steering head. The later 750s and 850 frames and triple clamps have a different frame rake angle and can be used in one configuration but not in the other - I forget which but think that you cannot use 850 triple clamps in a 750 frame although the other way round is OK.
There are many subtle differences in oil tanks, battery trays, hubs, mudguards etc that might make them unsuitable for use with your particular collection of parts, so a detailed knowledge of Commandos is useful if not vital in building something out of a collection of parts.
I would echo what others have said about trying to start with some kind of project that is at least partially complete, if you have matching frame engine and gearbox numbers this would be a good start although finacial considerations are important. i think if you keep your eyes open you might be able to locate something partially complete for the same price as an engine on e-Bay.
Good luck with your quest, a set of triple clamps is a fine basis for a new project!
:x :lol: :roll: :wink:
