Carb Body & Bowl Questions 70-73 & 74-75

[Jerm]

Can someone point me in the direction of ways to distinguish between 70-73 carb bodies and the 74-75 bodies? Same thing with the bowls. Is there any interchangeability between the bodies and bowls on these years with the difference in the needle jet? Bowls are marked with an A on the bottom, but one of the bowls has something else stamped in the same location.

Trying to figure out if the carbs in the images are actually 74-75 as the brass indicates. Pilot jet is Mikuni 45. Main has been replaced with a no name 128. Needle jet is the Mikuni short Z-6 with a fresh O Ring. Needles are 4N8-4.

These came with a batch of early bikes and parts I bought a while back.

Plugs indicate everything is way too rich. Trying to figure out if it is the no name main jet or a mixture of incorrect brass in the wrong bodies.

Thanks in advance.

 

[TwoManyXS1Bs]

Those are definitely not the 70-71 carb body parts. 70-71 carbs each have their own enrichner valves, mechanicaly interconnected by a u-shaped metal band, and both carbs have complete/drilled enrichner circuits, both in the carb body and in the bowls.

Yours have the single enrichner valve (left carb), enrichner crossover tube, blanked enrichner pickup in right carb body. Bowls have the pre-76 bleed air circuit, with brass standpipes for bowl venting. Closely check the carb guide and carb threads' pictures. Double-check the flat/raised floor descriptions and the air bleed configurations.

I'm gonna guess 72-73...