Chemical Two-Stroke Exhaust System Decoking

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SuzukiTom
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Chemical Two-Stroke Exhaust System Decoking

Post by SuzukiTom » Mon Mar 02, 2009 8:00 am

There is another way to remove the built-up carbon and oil in the exhaust system of a two-stroke exhaust. We used this method back in the '70s at a shop in-town where we couldn't use the thermal method due to the smoke created.

This is a SERIOUSLY dangerous cleaning solution, so caution needs to be exercised in its use!

Mix a ratio of 3-4 pounds of dry caustic soda to 1 gallon of water. Depending on the size of the exhaust system, you'll need about 5 gallons.

Cap off one end of the exhaust pipe, and seal off any other holes you might have where the solution might leak out of the pipe. Prop up the pipe vertically in a drum or bucket that can hold the entire amount of the solution if it happens to leak out of the pipe.

Slowly fill the exhaust pipe full of the caustic soda/water solution. Don't get any on you, it will burn your skin! Wash off immediately if you do.

Let stand in the pipe overnight. Dump out the mixture and throughly flush out the exhaust system with clean water.

This mixture also will degrease/depaint cast iron and steel parts. Don't use it on aluminum parts, it will eat them up!

HTH,

Tom
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Idahopaul » Mon Mar 02, 2009 10:23 pm

caustic soda, so like draino? where else can you get it and in that much volume.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by SuzukiTom » Tue Mar 03, 2009 5:09 pm

Idahopaul wrote:caustic soda, so like draino? where else can you get it and in that much volume.
Caustic soda (Sodium Hydroxide) is one of the ingredients in Draino, but it's pretty watered down. You used to be able to get the stuff from janitorial supply stores. It's still used in the making of soap, and you can get it in small lots from hobby stores. I recently bought 40lbs from http://www.aaa-chemicals.com/ which although pricy, should be a lifetime supply for me.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Jimny » Fri Mar 13, 2009 3:21 pm

What will it do to the Asbestos liner in the expansion chamber?
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by stevec » Fri Mar 13, 2009 3:44 pm

Jimny wrote:What will it do to the Asbestos liner in the expansion chamber?
On hardtops, it vaporizes the asbestos, and vents it to the cabin. :flush:

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Re: Chemical Two-Stroke Exhaust System Decoking

Post by SuzukiTom » Fri Mar 13, 2009 6:14 pm

Ha ha!

I hadn't really thought about the lining in the expansion chamber, but it couldn't be any worse on the asbestos then burning the carbon out. I'll be doing this procedure this weekend, so I'll let you know.

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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Jimny » Sat Mar 14, 2009 3:52 am

Well the asbestos is made to handle the fire and heat but I didn't know what a chemical like that would do to it.

Unless we take some and dip it in that stuff we probably really wouldn't know. I cut open an expansion chamber one time, I wish I knew what I did with it, then we could dip it into the chemical and see if it does anything to it.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Myers » Sat Mar 14, 2009 10:44 pm

Do not know for sure but my guess is the caustic would not harm the asbestos but it might be removed during the washing and rinsing. With heat and age asbestos can become friable (crushed, crumbled or pulverized to powder with the power of a human hand)

We had considerable caustic containing pipe and equipment in the refinery. I know some of it had been insulated with tin covered asbestos since built years and years ago.

The properties that make asbestos such a great insulation are it is very,very durable and is made up of very very small fibers (which makes for lots of air space trapped between them) . Both of these also serve to makes it a very bad health hazard.

If you want the bulk caustic try looking in phone book for Chemical Cleaning companies.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by deimos » Tue Mar 24, 2009 5:58 am

Gear Head, Any update on the results?
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by SuzukiTom » Tue Mar 24, 2009 5:26 pm

Well, I had a bit of a delay, I filled the system with straight water to look for any and leaks. Found a few pinholes that I had to weld up, and now it's sitting with the caustic soda/water mixture in it. This stuff is self-heating, since it's reacting with the oil/carbon in the exhaust. I'm going to wait 24hrs before I drain it out and take a look at the progress. I may have to let it go for a while longer, it was pretty gunked up. The header pipe had deposits that were 1/4 inch thick, and the tail pipe was at least 25% plugged.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Myers » Tue Mar 24, 2009 7:31 pm

If you get it cleaned out you will not believe the difference in performance.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by SuzukiTom » Mon Mar 30, 2009 6:12 am

Well, I drained and flushed the lye solution out of the exhaust system, and it seems to have worked ok, and it didn't damage the fiberous stuff in the expansion chamber. There is still a thin layer of carbon in the back (muffler) section of the exhaust, but it's a lot better then it was. Now I've just got to take the used solution down to the city hazardous waste disposal center (about 3 gallons).

I'd have to say that I would have prefered to use the thermal method of decoking the exhaust, and only used the chemical method because of where I live.

Tom
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by Myers » Mon Mar 30, 2009 8:25 am

Being considerate of neighbors is not wrong. Glad it worked. Let us know on performance changes. Daily driving with some long drives mixed in seen to help a lot in keeping it clean. Took 'Miss Alice" on approximately 40 mile round trip last week and she ran better when I got home than when I started.
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Re: Chemical Two-Stroke Exhaust System Decoking

Post by lj20Colorado » Mon Mar 30, 2009 7:18 pm

suzuki tom is there a way you can show befor and after photos? cant wait to hear the results from the driving and seeing if it helps with the performance thanks
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