Author Topic: HMCB 750 ---HM300  (Read 1332 times)

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Offline Sgt.Pinback

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HMCB 750 ---HM300
« on: March 14, 2014, 11:40:12 PM »
Hi,

what is the difference HMCB750 vs HM300 and which one was used when?

Thanks!
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Offline nccb

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Re: HMCB 750 ---HM300
« Reply #1 on: March 15, 2014, 05:46:59 PM »
When I look at mine (341) the hmcb 750 precedes the pipe number. Wonder if it was just a stamp to denote it was for the 750?

Offline Sgt.Pinback

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Re: HMCB 750 ---HM300
« Reply #2 on: March 16, 2014, 09:29:37 AM »
I refer to HMCB750 pipes without "341"
« Last Edit: March 16, 2014, 09:33:48 AM by Sgt.Pinback »
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Offline Old Scrambler

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Re: HMCB 750 ---HM300
« Reply #3 on: March 16, 2014, 04:59:54 PM »
Those are the No Number type used on sandcast and most other production through 1970. HM300 pipes began on late production K0 and through K1.  The very earliest version of the no number pipes are known as Lotus Root style.............they have a slightly different baffle mount and a 2mm difference in the height of the standing seam on the mufflers.
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Offline Sgt.Pinback

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Re: HMCB 750 ---HM300
« Reply #4 on: March 16, 2014, 11:09:54 PM »
Thank you for explanation.

 Beside the number no further differences ( eg sound)?
« Last Edit: March 16, 2014, 11:12:40 PM by Sgt.Pinback »
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Offline Old Scrambler

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Re: HMCB 750 ---HM300
« Reply #5 on: March 17, 2014, 09:28:11 AM »
The 300s have a very modest amount of extra wrap on the baffles..............so to some people they sound different.............but both are less restrictive and louder than the 341s.

Replacement baffles are made with lighter-weight metal. Another difference is the later 300s came with welded cap-bolts to make removal quite difficult.
Dennis in Wisconsin
'64 Triumph Cub & '74 Honda CB750 Bonneville Salt Flats AMA Record Holder (6)
CB750 Classic Bonneville Racer thread - http://forums.sohc4.net/index.php/topic,135473.0.html
'63 CL72 Project(s)
'66 CL77 Red
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'73 750K3 Owned since New
'77 750F2 Cafe Project
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Offline markb

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Re: HMCB 750 ---HM300
« Reply #6 on: March 17, 2014, 03:40:54 PM »
To the best of my knowledge none of the no number pipes, including the early Lotus Roots, have anything stamped on them.
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Swoop

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Re: HMCB 750 ---HM300
« Reply #7 on: March 17, 2014, 04:42:28 PM »
To the best of my knowledge none of the no number pipes, including the early Lotus Roots, have anything stamped on them.

+1 ...

Offline Sgt.Pinback

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Re: HMCB 750 ---HM300
« Reply #8 on: March 19, 2014, 06:15:14 AM »
To the best of my knowledge none of the no number pipes, including the early Lotus Roots, have anything stamped on them.

Thanks for that info.



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