Topic: Rubber Insert 12195-300-300

[ZTatZAU]

K1 750...  I've always wondered about the twelve white rubber inserts that are in between the fins on the front of the cylinders.  Can anyone enlighten me as to their purpose?

Thanks!  ZT

[newday777]

The dampen sound vibrations

[ZTatZAU]

The dampen sound vibrations

Interesting!  Are they really dampening the sound of vibrating cooling fins? Or some other vibrations?

EDIT:  I did a little searching and found several theories on this topic.

Apparently, Honda installed the rubber inserts to..
1) Reduce noise caused by wind passing through the fins at highway speeds.
2) Reduce crackling/tinkling noises caused by the hot fins as they cooled down after shutdown.

FWIW!  ZT

[newday777]

I think I read it was #2, heating and cooling

[Tracksnblades1]

Prevents fin cracking from vibration fatigue…and the vibration noise ring….

Old air cooled dirt bikes, especially the bigger bore 2 strokes had them too

[dave500]

yeah ive had yammy dt/it 400s with those rubbers,its for "fin ring"those dirt bikes had way deeper fins than honda road bikes.

[MauiK3]

They are hard to find as well, and not cheap. I'm sure someone here will come up with a link.

[Tracksnblades1]

yeah ive had yammy dt/it 400s with those rubbers,its for "fin ring"those dirt bikes had way deeper fins than honda road bikes.

Yep had a dt400, then a yz400 mono. Bought a it400 with the shift housing broke off and the engine was in a milk crate. Sold it right after installed donor cases..the YZ was a light switch but it was more of the softer type of light switch as compared to my buddies MX360…

[PeWe]

CB750 has vibrations around 4500-4800 rpm due to engine resonance by design.

I had a bad sound from engine in that rpm range. It was 1 or 2 exhaust spigots that were not tightened enough
Any other equipment not tightened enough can start to sing at 4500-4800 rpm area.

I guess the cylinder fins will sing too without the small rubber pucks.

When thinking about it, the nice high pitch singing sound can be heard when cruising evenly at that rpm range.

[Alan F.]

Are there any possible substitutes for them?

[PeWe]

I got a bunch with the JMR billet block from Mike Rieck.
He might know.

The UK guys have mentioned better priced alternatives in a thread somewhere the last year.

[newday777]

I also remember there was someone posted they had a bunch,  I was thinking it might have been HondaMan? Maybe it was Mike?

[PeWe]

I think it was Mike.
Nurse Julie commented in same thread if I remember correctly.

Here from the UK forum where Nurse Julie recommend one forum member having alternatives.
http://www.sohc.co.uk/index.php?topic=28700.msg270850.msg#270850

[CycleRanger]

Partzilla shows having some but they're pricey.
https://www.partzilla.com/product/honda/12620-286-000
Likewise CMSNL.
https://www.cmsnl.com/products/rubber-insart_12620286000/

The PN has been superseded by the earlier PN, 12620-286-000

It looks like grey ones are no longer available.

[bryanj]

Back in the 70's NP gasket kits came with a bag of them and nobody i know ever fitted them so in some shop somewhere will be loads of them!

[PeWe]

A lower priced alternative
https://www.ebay.com/itm/295047227940?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=zgaphpanrkm&sssrc=4429486&ssuid=XgCEg0CPSya&var=&widget_ver=artemis&media=COPY

[Alan F.]

What's the distance between fins? I wonder how these 15mm silicone beads would work?
https://www.ebay.com/itm/235108930287?hash=item36bd9592ef:g:q7wAAOSwN~tkxctT&amdata=enc%3AAQAIAAAA0Ogw%2BITAxsiLphH0gO%2FUUh%2BiUg2L7iqaUIWNxd835uhv4r0TKXagmmHSi4U20k8PxqmJKxmIC7efVA6Xl0rw6c0kJMjvp6nnbSMhDl8WO6m0vSgnPdi70H40nUeTPNDXpgLC421A%2BrfjJ2jSlpY6GDo%2BaJeNmYgIIcPtZRQ3Lv8ETtLgPpUVJuqOt0fAtLQrdClLYNmOE5EdRPFzbxQ4rul1Pmp%2FhhRUR6c7qxIREcVDQ%2Bp2BwB4LTe5E8NE8oRtMuINoPCqlMlkBJCan9CGdwo%3D%7Ctkp%3ABk9SR9Ljh6eCYw