How to: Restore your carburetor insulators and rubber bits


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NobleHops
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How to: Restore your carburetor insulators and rubber bits

Post by NobleHops »

I got wind of this technique on the SOHC board and finally got a chance to try it last night, with success mostly, and a couple of lessons learned that I'll pass along.

These are the culprits (along with some SOHC rubber bits), below:

Image

The black rubber/plastic donuts that sit between the carburetors and the cylinder head - AKA the "insulators' in Honda-speak. Over 30 years or so and a few thousand heat cycles, these dry out, get hard, sometimes leak leading to strange running conditions, and make installing and removing the carbs a larger pain in the arse then it needs to be.

You can buy replacements! Randakk's Cycle Shack will sell you really nice high quality replica parts for $110 for a set of 6, plus tax and shipping:

http://randakks.com/collections/honda-c ... master-kit

Or there are a few sellers on eBay that sell nice replacement sets for $70.00 plus tax and shipping, for example:

http://www.ebay.com/itm/BRAND-NEW-6PCS- ... 1c3d01f714

Or you can restore the ones you have, along with any other hard rubber bits you have, using 4 oz of wintergreen oil for roughly $20:

http://www.amazon.com/Wintergreen-Essen ... n+oil+4+oz


In my case I popped for the set from Randakk, but that's because I didn't know about the wintergreen technique. The active ingredient in wintergreen oil that is helping is called methyl salicylate, and this is how to use it, some cautions I'd take if I were doing it over, and how it can go wrong.

You need:

4 oz of the wintergreen oil.

A hot plate or a VERY UNDERSTANDING significant other that LOVES the smell of wintergreen lifesavers and wants to smell it for a while, in which case you can do it in your house on your stove.

A pasta pot that you may not intend to use for pasta again, WITH A LID!

Tongs.

A fan.

Instructions:

Clean the insulators well, get them nice and squeaky clean

Put your hot plate and pasta pot in a doorway or maybe just outside, or use a fan to direct fumes away and outside (see above).

Fill the pasta pot with a gallon of water, add the wintergreen, cover, and bring to just below a boil, roughly 200 degrees.

Toss in the insulators, lower the heat to medium give them a stir now and then, and simmer for 30-60 min.

Fish them out, rinse them off, declare victory. Your old rock-hard insulators are now much softer and more pliable, will install easily and make installing the carbs much easier too.

Image

What, you ask, could possibly go wrong with such a simple process?

Take a look at this photo below, paying particular attention to the large rubber plenum>airbox seal (CB400F, BTW) that's just below the bottle of wintergreen oil.

Image


See how it's looking a little ragged, punky? That gasket and the other airbox tubes off this set were all decomposing I think, felt slightly gummy to the touch before I dunked them. Not sure what happened to them, maybe some solvent got sprayed on them before I got them, but once they were in the pot WITH ALL THE OTHER STUFF (mistake) they commenced to falling apart, and gooey spooge was floating around and getting on the other parts. I stopped short of the full cycle, fished my parts out pronto and cleaned them off before the stuff cooled and hardened, and got them about half as good as they could be - still a huge improvement in just 15 min of simmering.

At left is one of the snorkels from the set that was half punky, at right is one from the other set that came out really well:

Image

As above, plenum seal:

Image

So - yes I think you can do pretty much any rubber part in this solution, but pay close attention when you do, and maybe do any suspect parts separately and watch carefully to see what happens.

I'd also suggest you do a better job of fumes containment and evacuation than I did, including maybe wearing a respirator. My sinus is still lightly infused with wintergreen today, and I bet my lungs are too, and it's not all pleasant. My garage and office on the other hand are TOTALLY infused with wintergreen, despite having the garage and side door open for an hour after I was through. It's not that pleasant IMO.

Last thought: I am betting I can reuse the solution, so I bought an unused paint can and saved it.

Image

Good luck, and report back if you try it!

N.
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: How to: Restore your carburetor insulators and rubber bi

Post by steve murdoch icoa #5322 »

Thanks for the info, Nils.
I am following a guy on www.thegsresources.com who is doing the procedure.
He has not reported back with final results other than the stench in his shop.

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Re: How to: Restore your carburetor insulators and rubber bi

Post by daves79x »

Thanks Nils - pretty amazing. Who knew?

Dave

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Re: How to: Restore your carburetor insulators and rubber bi

Post by tevan »

I heard of this before on the web but have never tried it. I checked my local walgreens and they didn't have it. I will try it out and thanks for the great write up on this.

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Re: How to: Restore your carburetor insulators and rubber bi

Post by NobleHops »

Update: one guy also does this without heat, with the wintergreen added to a gallon of xylene. Leaves them in for a few days, checking and stirring. Says he gets same result. Lots of upside in not heating, IMO, no pot or hot plate needed, no crazy fumes, etc. Anorher option!
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: How to: Restore your carburetor insulators and rubber bi

Post by ajs350 »

Thanks for sharing Nils. I have to take the carbs of soon and will try this to rejuvenate my insulators.

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Re: How to: Restore your carburetor insulators and rubber bi

Post by barryadam »

Yah, nice job NIls. Thanks for the instructional post with good picstures, as always.
You must have some redeeming qualities to Felicia.
And I'm sure the dog is really appreciative, too. :teasing-poke:

I'm going to keep this tip for my next project - a bunch of old Yamaha Enduros.

Barry

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Re: How to: Restore your carburetor insulators and rubber bi

Post by cbx6ss »

Question:
I spit my airbox on my 81 at its seam to clean. What might be the best adhesive to re-assemble? I am currently contemplating JB-Weld.
/r
Brad

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Re: How to: Restore your carburetor insulators and rubber bi

Post by NobleHops »

I think you want something thinner that will fuse the plastic Brad, along the lines of MEK. Or some variant of cyanoacrylate glue. How thick/wide is the surface area you need to glue?
Nils Menten
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Re: How to: Restore your carburetor insulators and rubber bi

Post by cbx6ss »

probably .25" max by 36 linear inches without going to the man-cave...

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Re: How to: Restore your carburetor insulators and rubber bi

Post by NobleHops »

cbx6ss wrote:probably .25" max by 36 linear inches without going to the man-cave...
For clarification are we talking about the airbox where the filter lay, or the plenum between the airbox and the carbs? In any event, I don't think JBWeld is the answer, it's not really an adhesive, and it has a lot of mass and bulk. I think you want a proper plastic glue that melts/fuses this plastic. I *think* this is ABS plastic, and that MEK might work, but apparently good old acetone might work too. Maybe try a dot of it to test?

Who knows for sure what kind of plastic this is?
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: How to: Restore your carburetor insulators and rubber bi

Post by cbx6ss »

nuf for me to give it a try. I'll let you know. Thank you for the info.
/r
B

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Re: How to: Restore your carburetor insulators and rubber bi

Post by cbx6ss »

ummm... Plenum between the carbs and box

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Re: How to: Restore your carburetor insulators and rubber bi

Post by NobleHops »

Report back on what you learn, will you Brad?
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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Re: How to: Restore your carburetor insulators and rubber bi

Post by daves79x »

If you are talking about the chamber that you can take the screws out of and pry apart - just clean the old stuff out of the grove and use black silicone to seal - if it was meant to be glued from the factory, you wouldn't be able to take it apart.

Dave

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