Topic: Rubber inserts

[DanJ]

Is there a cheaper alternative to paying 3.67 a piece for the cylinder rubber inserts P/N 12620-286-000 ? for 20 of them around $74 plus shipping.

[FrankenFrankenstuff]

What do they look like? All the same?

[DanJ]

Yes they are the white rubber inserts that go between the cooling fins

[wowbagger]

Do a search, I remember HondaMan talking about an alternative to those but I can't remember the details. I'll see if I can dig it up.

[MCRider]

What do they look like? All the same?

Yes the little rubber chicklets that go between the fins. I just bought some retail, came in black.

Need to withstand the heat. I can send you 1 as a sample if you like.

Honda man and others were struggling with an alternative via snipping some rubber plugs, etc. Didn't see anything that I could do reasonably well.

[wowbagger]

There it is:

http://forums.sohc4.net/index.php?topic=122379.msg1400329#msg1400329

[flybox1]

I remember that too.  hi-temp silicon plugs?
wonder if you can find viton cord?
~10mm OD, by the meter

[nccb]

I seem to remember him having issues with them later though. . .

[flybox1]

yes, he did.
GRAINGER had some solid silicon (500F) cord, 3/8" OD, 10'  @ $16
6" would probably yield enough spacers for an engine.

http://www.grainger.com/product/Rubber-Cord-6RTH9?s_pp=false

Viton is good to about 390F, most expensive $96/10'
EPDM, Buna, and Neoprene are much cheaper, but only good to about 250F..

[lucky]

Is there a cheaper alternative to paying 3.67 a piece for the cylinder rubber inserts P/N 12620-286-000 ? for 20 of them around $74 plus shipping.

The ones that go between the fins?
If so ,you do not even need them.

When this motorcycle first was introduced there was some tinkling noises from the fins expanding and contracting when the engine was cooling off.
So those rubber things were put in to dampen the noise.
Later in Honda put more silicon into the aluminum to keep the expansion and contraction down and they were eliminated. You do not need them.

Also after 40 years the metal has stabilized and they probably make very little noise.

At that time all aluminum engines were a new thing and a lot of things were unknown, like the expansion and contraction noises. It bothered some people and they did not like it.
Now it does not bother most people.

[flybox1]

they certainly weren't eliminated on 750 F2/3 engines

[MCRider]

they certainly weren't eliminated on 750 F2/3 engines

They are on the K8 microfiche, too.

I think I've read that they were developed and retained to suppress high frequency noise, which is amplified behind a fairing, and high frequency cracking.

MAybe they dropped them after 78 SOHC.

[lucky]

they certainly weren't eliminated on 750 F2/3 engines

They are on the K8 microfiche, too.

I think I've read that they were developed and retained to suppress high frequency noise, which is amplified behind a fairing, and high frequency cracking.

MAybe they dropped them after 78 SOHC.

I have never seen or heard of fins cracking from missing rubber inserts.
40 years and I have never seen that.
Every time I see broken fins it was a hammer that broke them.

[FrankenFrankenstuff]

I can make them out of silicone. I have baked the stuff to 500° with a heat gun. Gets stinky but doesn't......melt. PM me some dimensions and I can whip something up for testing.

[flybox1]

Recently took all out of my F2 engine
i'll mic a few when i get home and post....

[MCRider]

they certainly weren't eliminated on 750 F2/3 engines

They are on the K8 microfiche, too.

I think I've read that they were developed and retained to suppress high frequency noise, which is amplified behind a fairing, and high frequency cracking.

MAybe they dropped them after 78 SOHC.

I have never seen or heard of fins cracking from missing rubber inserts.
40 years and I have never seen that.
Every time I see broken fins it was a hammer that broke them.

I'm not saying they are necessary, I'm saying what I've heard is the reason. I've never heard that masking the sound of it cooling down was a reason, just saying.

But...really, how many engines have you ever seen with them missing anyway? I mean people don't just go around and pop them out.

[DanJ]

Thanks for the replies guys. I have all mine still in the cylinder but was going to sand blast and paint and figured I'd replace them but not for that type of money. I don't think they would be an easy part to fabricate because of the tabs on each insert that hold them in place. I'll probably try taping each one off when I spray to keep most of the paint off for now if they survive sand blasting.

[flybox1]

Just for reference....
Small 10mm OD x 7mm width.
(Includes largest width, which would allow for a snug fit into the fin retaining holes)
Large 13mmOD x 7mm

[kmb69]

they certainly weren't eliminated on 750 F2/3 engines

They are on the K8 microfiche, too.
I think I've read that they were developed and retained to suppress high frequency noise, which is amplified behind a fairing, and high frequency cracking.
MAybe they dropped them after 78 SOHC.

I have never seen or heard of fins cracking from missing rubber inserts.
40 years and I have never seen that.
Every time I see broken fins it was a hammer that broke them.

I'm not saying they are necessary, I'm saying what I've heard is the reason. I've never heard that masking the sound of it cooling down was a reason, just saying.
But...really, how many engines have you ever seen with them missing anyway? I mean people don't just go around and pop them out.

If I remember correctly, DanJ is restoring a Sandcast and that's what makes them important to us restoration freaks. Early ones were kinda off-white to grey.

Gotta have tits on each side to hold them in the little fin holes. Gotta push kinda hard to install them as they come new, a bit oversize to accommodate casting variations. They kinda conform to the casting draft after a little running at temp.

[nccb]

I have a K4 and mine are a grayish white as well.

[FrankenFrankenstuff]

I can make them , no problem. Even off white to color and out of high temp silicone.

[MCRider]

I can make them , no problem. Even off white to color and out of high temp silicone.

I thought so! Don't forget the top and bottom locator nipples.

The dull whites will be in demand as the OEM Honda ones are all black it seems. Up close the gloss black on a black cylinder and head looks nice, but is lost from a distance. For those of us who want farkles to be seen, the white in a black set of fins could be seen easily.

Of course frame color or body color would be really trick.

[FrankenFrankenstuff]

Material is an off white but can be pigmented to a degree. I will post pics up next week. Thanks for the new product boys! My wifeypoo likes it when I keep busy and out of trouble.

[DanJ]

That would be nice, Plus you don't live all that far away

[DanJ]

If I remember correctly, DanJ is restoring a Sandcast

Nope doing a 73 K-3 but I like original, if it was there before I messed with it, I like it there after.

[kmb69]

Sorry, wrong Dan. DanR, I think.

[FrankenFrankenstuff]

DonR

[kmb69]

Thank you. I must be getting old or something.

[FrankenFrankenstuff]

Just for reference....
Small 10mm OD x 7mm width.
(Includes largest width, which would allow for a snug fit into the fin retaining holes)
Large 13mmOD x 7mm

[FrankenFrankenstuff]

[FrankenFrankenstuff]

These are the smaller ones. I wasn't sure about the nipples so I did double.

[MCRider]

Wow Joe, Looks great. A little late for me.     Already paid top price for OEMs.

[flybox1]

In looking at the ones i pulled out of my 750F2 head, it looks like the nipples were not part of the original design, but the spacer was taller than the fin space, and the nipples were 'formed' by the pressure of the spacer between the fins. ICBW 
Anyway, for the new spacer design, the nipple height on each side will need to be 1/2 the width of the fin or they wont all stack correctly (as the one above and the one below must share the nipple hole space)

Franken - i'd be in for a set if you do grey/black.

[MCRider]

In looking at the ones i pulled out of my F2 head, it looks like the nipples were not part of the original design, but the spacer was taller than the fin space, and the nipples were 'formed' by the pressure of the spacer between the fins. ICBW 
Anyway, for the new spacer design, the nipple height on each side will need to be 1/2 the width of the fin or they wont all stack correctly (as the one above and the one below must share the nipple hole space)

Franken - i'd be in for a set if you do grey/black.

Having just bought the OEMs, the nipples are part of the rubber insert by intention not by pressure.

Also, the rubbers go in every other fin, skip a fin. So their length is not critical. Except in the case of the bottom 2 cyl fins where they were consecutive.

However, the nipple on the OEM was smaller than 1/2 the thickness of a fin, so it's not an issue with OEM.

My comments are for a K2. Other models may vary. (F2?) Though the quantity "20" was in every fish I've seen on Ks. It would take more than 20 to put them in every fin without skipping.

[flybox1]

Just looked through my pictures.  20 as well on the 750F2 cylinders.
10 in front and 10 in back, with one in each of the bottom two fin spaces.
Every other space above those...

[MCRider]

Just looked through my pictures.  20 as well on the 750F2 cylinders.
10 in front and 10 in back, with one in each of the bottom two fin spaces.
Every other space above those...

Yup, same as mine.     K2