HM300 vs. HMCB750 (no 341)

[Sgt.Pinback]

Can you please tell me which came when?

[Steve Swan]

wow.  haven't seen that one b4 !

[Sgt.Pinback]

wow.  haven't seen that one b4 !

In sohc4 I heard, it is what you call "no number pipe" - is that correct?

[hondasan]

A picture of the end of the silencer showing the baffle would help. I recall some European market bikes (after the No no. pipes) were not stamped HM300, rather stamped as shown in Sgt Pinback's picture. They also had  baffles without the vertical bar in the HM300 and earlier pipes - but NOT "341" type . There is a different part number shown for these markets (Germany, France, and a couple of others, etc), ending "620".

Cheers - Chris R. 

[ashimotok0]

I have 4 NOS sets of carb needle kits which I bought in error to be used evidently with the German etc. exhausts. Wonder why they had a variation in exhaust types for these markets. Do you know Chris?

Cheers... AshD

[Sgt.Pinback]

A picture of the end of the silencer showing the baffle would help. I recall some European market bikes (after the No no. pipes) were not stamped HM300, rather stamped as shown in Sgt Pinback's picture. They also had  baffles without the vertical bar in the HM300 and earlier pipes - but NOT "341" type . There is a different part number shown for these markets (Germany, France, and a couple of others, etc), ending "620".

Cheers - Chris R. 

I found an almost 30 year old photo when the bike was mine.
Here you see the baffles of that HMCB750 pipes.
Its the blue one on the right side.





Chris, what do you think: was HMCB750 before or after HM300?

What is stamped on a "No number" pipe, does anybody have a photo?





BTW the story behind the bike/exhaust:

Those two K0 had been mine early 80th when I was a student. I made one good out of two. The green one was sold when finished, the blue one I traded some years later in 85 with a CBX 1000 at a local HONDA dealer.

That dealer kept the K0 for almost 25 years in a cellar. He passed away a few years ago. So she was sold. Sadly I didnt knew.
I found "my" KO yesterday in Stuttgart on the Retro Classic fair. Still has the same tyres!

She can be seen here:

http://www.motorradonline.de/testsfahrberichte/auf-achse-mit-honda-cb-750-four-muench-4-1200-tts-und-mv-agusta-750-s/527338#1-505896

[Steve Swan]

i'm talking about the "hmcb750" stamped on teh pipe.  usually it's no stampings for sandcast.  hm300 for some ko and all k1.

[benjixt]

A picture of the end of the silencer showing the baffle would help. I recall some European market bikes (after the No no. pipes) were not stamped HM300, rather stamped as shown in Sgt Pinback's picture. They also had  baffles without the vertical bar in the HM300 and earlier pipes - but NOT "341" type . There is a different part number shown for these markets (Germany, France, and a couple of others, etc), ending "620".

Cheers - Chris R.  

Hello

In France the french sandcast (vin 101xxxx) the k0 diecast and the k1 received this exhaust called hmcb750
The baffle is différent There is only 1 circle on the hm cb750  the 341 got 2 circles baffle
The hmcb750 baffle CAN be removed like the hm300

The hm300 is more loud  than the hmcb750
The hmcb750 is more loud than the 341

As far i Know this exhaust Was on the french german switzerland  ...spain

[benjixt]

I have 4 NOS sets of carb needle kits which I bought in error to be used evidently with the German etc. exhausts. Wonder why they had a variation in exhaust types for these markets. Do you know Chris?

Cheers... AshD

Please can you give me the number engraved on the needle

Thank you

[Sgt.Pinback]

  
[/quote]

Hello

In France the french sandcast (vin 101xxxx) the k0 diecast and the k1 received this exhaust called hmcb750
The baffle is différent There is only 1 circle on the hm cb750  the 341 got 2 circles baffle
The hmcb750 baffle CAN be removed like the hm300

The hm300 is more loud  than the hmcb750
The hmcb750 is more loud than the 341

As far i Know this exhaust Was on the french german switzerland  ...spain

[/quote]

Good info, thanks.

[Steve Swan]

I have 4 NOS sets of carb needle kits which I bought in error to be used evidently with the German etc. exhausts. Wonder why they had a variation in exhaust types for these markets. Do you know Chris?

Cheers... AshD

i'm suspecting it was government noise regulation.  i've always understood europe had/has stricter noise/pollution laws than usa. 

since a more restrictive exhaust would would affect a/f intake and exhaust flow, you'd have to adjust a/f ratios, using different needles, nozzles and jetting.

[ashimotok0]

I have 4 NOS sets of carb needle kits which I bought in error to be used evidently with the German etc. exhausts. Wonder why they had a variation in exhaust types for these markets. Do you know Chris?

Cheers... AshD

Please can you give me the number engraved on the needle

Thank you

Guess it was something to do with noise restriction then and explains the needle sets I have. They would have been used for the different carburation needed for the more restrictive exhausts.

The P/N of the kit is 16012-300-611.  I will try to read the number but they are in unopened Honda packaging containing needle, jet and little circlip.

Cheers ... AshD

[Sgt.Pinback]

So there were no HM300 in France/Germany....?

[ashimotok0]

So there were no HM300 in France/Germany....?

Attached what info I have available. Sorry didn't scan properly (Too early in the morning !!!!!!). The 1st column on the right, after the description is CB750, second is K1 and third is K2 !  Obviously the 'CB750' is the earliest part but unsure if 'K0' or Sandcast, as there is probably much earlier parts book than the one I have. The 'diffuser' Part Number is different too, as Chris suggested.

The last info on the right are the country codes and looks like France, Germany, Holland for the exhausts with the '420' suffix but I may be wrong. The two letter code is a bit fuzzy but may be 'European Direct Sales' .... Sure ChrisR will know these codes!! Will check the engravings on the needles tonight.

Wonder what internal design later HM300's were made to in terms of noise, emissions etc. Maybe they did not meet the German ect. standards or maybe changed to a 'harmonized' standard? If the latter, which carb needes should we use with the last batches of HM300's with the 'verbage' stamped onto them. Will have to venture into the loft and read the 'verbage' on my NOS set.

Cheers .. AshD

[benjixt]

I have 4 NOS sets of carb needle kits which I bought in error to be used evidently with the German etc. exhausts. Wonder why they had a variation in exhaust types for these markets. Do you know Chris?

Cheers... AshD

Please can you give me the number engraved on the needle

Thank you

Guess it was something to do with noise restriction then and explains the needle sets I have. They would have been used for the different carburation needed for the more restrictive exhausts.

The P/N of the kit is 16012-300-611.  I will try to read the number but they are in unopened Honda packaging containing needle, jet and little circlip.

Cheers ... AshD

Hello
if you arrived that will be cool to give us this great info !!
thank you