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Author Topic: Rubber things  (Read 910 times)

Raj V

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Rubber things
« on: August 28, 2011, 06:16:09 PM »
Hi all,

What are these black rubber strips on the engine (image attached)? They are not secured in any meaningful way and are starting to fall off. What will be the best way to secure them? Thanks.

wokka

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Re: Rubber things
« Reply #1 on: August 28, 2011, 06:31:50 PM »
They are simple dampers used on the alloy barrels to reduce noise and vibration

As for fixing, hopefully someone else can help

Desi Bike

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Re: Rubber things
« Reply #2 on: August 28, 2011, 06:33:45 PM »
The best way to secure them is to take them off and put them in a small plastic baggy in a drawer.  

They are there to stop some harmonic ringing at certain engine speeds on some bikes. Many people remove them with no ill effect.  There is better cooling airflow around the fins without them.

The choice is yours to you keep them in of course. Mine are still in, but come loose every now and then

If you want to keep them in place, a light tap with a rubber mallet can push them back into place.
میں نہیں چاہتا کہ ایک اچار
میں صرف اپنی موٹر سائیکل پر سوار کرنا چاہتے ہیں

P. Schraub

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Re: Rubber things
« Reply #3 on: August 28, 2011, 09:12:06 PM »
Hello Ray V,
        The best thing you can do with these black rubber dampers is to re-locate them........to the garbage can ! They are there to satisfy the EPA and to my ear, make no difference. They also restrict airflow around the cooling fins. Yank em' !

Arizoni

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Re: Rubber things
« Reply #4 on: August 28, 2011, 11:21:13 PM »
Raj V:
If you really like them and want to keep them from falling off remove them and apply a very light coating of Silicone Rubber RTV to the surfaces that will mate with the engines fins.
Once cured the RTV will bond them in place well enough to keep them from falling off.  It will also serve as a lubricant to help you reinstall them.

Personally, I don't like them and as I live in a place where the daytime temperature can be 115*F (46.1 C) I would rather have the fins totally exposed to the air for cooling.

I removed mine and I can not hear any difference in sound.
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

rbelyk

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Re: Rubber things
« Reply #5 on: August 29, 2011, 01:02:02 AM »
I took mine off and don't notice any difference in sound.. ??
I think they look better off but some folks like the look of them
 :)
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custom 1953 Triumph

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singhg5

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Re: Rubber things
« Reply #6 on: August 29, 2011, 01:16:57 AM »
Raj:

I had these rubber noise damper pads in my G5 for 2 years but I took them out recently - I should have taken them off earlier.  

They marginally muffle the resonating sound of valves / rockers but they do block the air that cools the engine. In my view the advantage of cooling the engine outweighs the very slight difference in sound (mind you most people do not even notice difference in sound with or without these damper pads). I took them off, cleaned them and put them aside in a plastic bag  ;D !
« Last Edit: August 29, 2011, 08:41:30 PM by singhg5 »
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Desi Bike

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Re: Rubber things
« Reply #7 on: August 29, 2011, 01:25:27 AM »
mine looked to have been installed while the paint was still wet on the fins.
میں نہیں چاہتا کہ ایک اچار
میں صرف اپنی موٹر سائیکل پر سوار کرنا چاہتے ہیں

Raj V

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Re: Rubber things
« Reply #8 on: August 29, 2011, 04:48:44 PM »
Thanks guys. I'll take them off. Just something about half-hearted manufacturing that bugs me.

prof_stack

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Re: Rubber things
« Reply #9 on: August 29, 2011, 05:21:29 PM »
Thanks guys. I'll take them off. Just something about half-hearted manufacturing that bugs me.

Whoa!  Be careful with that statement!!  If you are bugged by that, then you've got a whole swarm on the way!   ;)
A Royal Enfield owner's cup is always half full.

barenekd

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Re: Rubber things
« Reply #10 on: August 29, 2011, 11:58:31 PM »
Took 'em off. They look too oriental.
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Tony in Glendale

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Re: Rubber things
« Reply #11 on: September 07, 2011, 12:05:28 AM »
I just hope they're not there to prevent the fins cracking due to vibration.  That could suck.

prof_stack

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Re: Rubber things
« Reply #12 on: September 07, 2011, 12:07:30 AM »
I just hope they're not there to prevent the fins cracking due to vibration.  That could suck.

 :D :D :D :D :D
A Royal Enfield owner's cup is always half full.

Tony in Glendale

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Re: Rubber things
« Reply #13 on: September 07, 2011, 12:30:00 AM »
Well, I worry about stuff like that ;)

Arizoni

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Re: Rubber things
« Reply #14 on: September 07, 2011, 01:20:47 AM »
Before removing mine I worried about it too.

In my work I found that vibration can do incredible things to materials.

On one of my many projects I once designed a power unit for a tank.  This was a small gas turbine engine with a gearbox, controls and accessories that drove a high power alternator.

Because it was going into a tank, weight was not an issue so I made the housing out of cast stainless steel with .200 inch thick walls.  To say it was "stout" would be an understatement.  A direct hit with a high powered rifle wouldn't have fazed it.

Anyway, part of its testing involved being placed on the "shake table", a large steel table that could be vibrated at an infinite number of cycles per second at various magnitudes of intensity.
This took place in a room filled with many large cabinets containing the power sources for the magnetic drives that moved the table.  (Before going into the room you had to remove your watches or anything that could be destroyed by intense magnetic fields).

The room was darkened with multiple strobe lights pointed towards the unit flashing away as the operator started turning up the power and frequency.  It reminded me a lot of Scotty in the Engineering deck of the Enterprise starship with its low hum getting louder and higher in pitch.

As the frequency and intensity picked up with the strobe lights flashing things on the engine started to move.  The CDI box on its soft mounts started wagging back and forth, the fuel pump and control started moving in a circular pattern about its mount, the turbine case stated changing from round to elliptical.  As the frequency increased the movement of some things started slowing while other things started moving faster.  As I watched, then  IT started.

IT was the hell for stout gearbox housings walls started moving!
The front face started moving in and out while the side walls with the engine mounts on them also started moving in and out.  I'm talking over 1/4 inch of movement!

Anyway, we had taken it far beyond its operating requirements and nothing broke.
After the test my good friend, the Chief of Engineering says to me, "Congratulations on the test and remember Jim, the world is made of Jello."

Anyway, getting back to the subject, if you notice there are a number of cast in cylinders that connect the fins on the cylinder to tie them together.
These are there specifically to prevent the vibrations in the engines operating range from exciting the fins and leading to metal fatigue.

Just to prove nothing bad was happening, after removing the rubber dampers I started the cold engine with my hand resting on the fins.
After running it up and down thru its normal speed ranges I didn't feel any of the fins beginning to vibrate beyond the normal vibration of a big 500 thumper.  This is good.

If the fins are producing any noise at all the magnitude of the vibrations is so small I don't think there will ever be a problem with metal fatigue.  :)
« Last Edit: September 07, 2011, 01:25:08 AM by Arizoni »
Jim
2011 G5 Deluxe
1999 Miata 10th Anniversary

Tony in Glendale

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Re: Rubber things
« Reply #15 on: September 07, 2011, 01:42:31 AM »
I saw shake tables like then when I worked at Douglas Aircraft in Long Beach CA.  The magnetic drives reminded me of giant speaker voice coils.  I guess they work on the same principle as a speaker too.  I never did see them in action though.

However I did have a 1979 VW Rabbit Diesel, so I know what vibration can do. ;)