Early CB750 Exhaust Systems

[Gene]

I know a man that has a set of 4 into 4 Honda exhaust pipes and mufflers. He does not know what year they are for.

How can you identify the various systems and know what bike they are for?  Is there a list somewhere that specifies which systems go with which bikes?

I have seen an "HM"  number on mufflers. This probably specifies the model, but how do you know which is which?



Thanks for your help.
Gene

[Piute]

I'd say thats going to be a hard one,every manufacturer has different ways(#s and names)to naming there parts(exhaust,pipe's,mufflers,slip-ons).I say this because looking for A "special" muffler for my "77"became a pain/but fun.Myself I'd get all the info you can on the pipes your referring to,1 peace or 4 peaces,Ya-no,start google-ing them #s different ways,Give the guys A picture they maybe able to spot it ?lil info on bike there off of helps too.
  ..Piute..

[Re-run]

I am not sure of the years for sure but the very early bikes had un-numbered pipes, very rare and expensive.
Next I think were hm300 pipes, used from 70 or so to 76, I think. After that I think it was hm341 pipes.
with 300s being worth more than 341s.