How to repair your damaged carburetor boot insulator

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We hear from a lot of people looking for a carburetor boot to replace the 20+ year old carburetor boot.
Since most of the time they are not available new you end up looking for an old one or perhaps you try to repair your old one.
So you get out some silicone and smear it around and it seems to work good for a little while and then it starts leaking again.
Now what?

Well, let me show you how we fix ours.
First off, if yours is fallen completely apart this method probably won't work
Let's take a look at this boot.
It is off a 91 KTM 300 DXC.

ktm 300 dxc carburetor boot insulator

ktm 300 dxc carburetor boot insulator.JPG (62.6 KiB) Viewed 20159 times

As you can see it is starting to get checked pretty bad.
I have fixed them in much worse condition then this so it is a easy repair.
None of the cracks go all the way through and from what I can tell the inside is smooth with no apparent defects.
So, get it CLEAN!!!!!!
I take our boots and put them on the wire wheel.
Don't ski this step or do a half baked job.
Get every square inch of it clean.

ktm 300 dxc carburetor boot insulator-2

ktm 300 dxc carburetor boot insulator-2.JPG (48.97 KiB) Viewed 20159 times

When you are done, look at what happened:

ktm 300 dxc carburetor boot insulator-3.JPG

ktm 300 dxc carburetor boot insulator-3.JPG (55.76 KiB) Viewed 20159 times

Many of the cracks opened up or were cleaned out so now we can see what is really there.

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The next step is to make sure the surface is completely clean of any dirt, debris, grease, oil, ect.
We like to use Acetone as it does a great job and dries extremely quick.
I do recommend that you wear some good Nitrile gloves while handling Acetone as it goes directly to your blood stream

Acetone

acetone.JPG (28.44 KiB) Viewed 20158 times

Now, look at the rag that I used to clean it with.
See the black?
If you don't take the time to really clean it your sealer won't get a good bond and you might as well not bother even doing this.

dirty rag.JPG (51.68 KiB) Viewed 20158 times

Get it CLEAN!!!

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Now that it is clean, clean, clean....
It's time to seal it up.
One of the best products that I have found is Permatex® Ultra Black® Maximum Oil Resistance RTV Silicone Gasket Maker.
Keep in mind that it is NOT fuel proof.
However, since you are not putting it on the inside of your boot then the fuel shouldn't really get on it, and since the air is being drawn in and not being pushed out, it is rare that the Silicone goes bad and looses adhesion.
Another nice quality is that it will protect the boot from further deterioration due to Ultra Violet radiation (Sun) and adverse weather conditions.
Here is what the manufacture says about it.

OEM specified. For dealership warranty requirements, Ultra Black® ensures extended drivetrain warranty compliance. Fast-curing formula. Sensor-safe, low odor, noncorrosive. Meets performance specs of OE silicone gaskets. Retains high flexibility, oil resistant properties through use of a patented adhesion system. Temperature range -65°F to 500°F (-54°C to 260°C) intermittent; resists auto and shop fluids and vibration.

Automotive applications:
Suggested Applications: Valve covers, oil pans, intake manifold end seals, timing covers, differential covers

Marine applications:

Suggested Applications: Valve covers, oil pans, intake manifold end seals, timing covers, water pumps, thermostat housings
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Note: There is no mention of fuel or application for motorcycles so use it at your own risk...
We have had really good experience with it and have some boot that are still going of almost a decade.
Here is pic of the actual tube.

ktm 300 dxc carburetor boot insulator permatex.JPG (59.38 KiB) Viewed 20158 times

As you can see, we have used it many many times

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Now it's time to fully coat the entire outside surface area.
I like to use a nitrile glove for this as well just to keep the goo off my fingers.
Boot after coating:

ktm 300 dxc carburetor boot insulator-4.JPG (73.98 KiB) Viewed 20158 times

Let it dry thoroughly.
Typically it takes about 24 hours to be fully dry.
If it is below 65 degrees I recommend that you wait 48 hours or even longer.
Now put your bike back together and go ride it

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It dried very nicely.
Obviously if your looking for show quality this procedure is not for you.
However, if you just need to protect the one you have or do a minor repair, this will give you years of usage for very low cost