In this months DON'T ASK,  I ran an email from a reader that went: 

Hello Rick,

I fly with a 2 stroke Rotax engine. We decarbonize every 80-100 hours.

The hardest part is the ring lands. Last year I came across Piston Kleen.

It was 60 deg out. I took two coffee mugs put my pistons in, filled them up with Piston Kleen and wrapped them in black plastic and put them in the sun. 3 hours later my pistons were spotless. Piston Kleen is water based so no bad smell etc.  Just sharing a thought.

Tom Eichhorn

Heart of Illinois Ultralights

It sounded interesting, and we gave Tom an answer:

Thanks for the neat tip.  We'll not only pass it on to our readers, we'll get some of the Piston Kleen and give it a try.

Here are the pistons we used for the test: 440 Maico, 250 Kaswasaki and GS 1100.

We contacted the makers of Piston Kleen, the Orison company, and ordered a gallon.  The claims by Orison are intriguing:

"Piston Kleen is a safe, effective and economical water-based cleaner engineered to remove baked-on carbon, fuels, oils and greases from tank and automotive engine parts. Developed to remove burnt-on carbon deposit in the piston rings on U.S. Army vehicles, Piston Kleen makes easy work of virtually all engine related soils. Simply soak the pistons/parts in Piston Kleen for 2 to 24 hours to remove even the nastiest build-up. Agitation and heat decrease soak time, but are not necessary.  Orison recommends agitation with a working temperature of  90 to 130 degrees F.   Piston Kleen is also great in manual parts washers and ultrasonics.

•        No DOT Transportation Restrictions

•        Biodegradable

•        Non-Toxic

•        No hazardous ingredients

•        Multi-Metal Safe

•        Non-flammable

•        No VOC

1 Gallon … $14.95

5 Gallon … $64.75

Stephen Gautreau picked some funky pistons from the darkest corners of his stock.	Piston Kleen comes in one, five and 55 gallon sizes.
Kawasaki 2-stroke piston.	Side shot shows blow-by deposits on piston.

As usual, we enlisted the services of Stephen Gautreau, owner of  SG Cycles,  (5635 E. Baseline Rd., Mesa, Arizona  602-705-5876)  for some genuinely crummy pistons.  He scoured the darkest corners of his shop and came up with some heavily carboned-up pistons, both two stroke and four stroke versions. 

The pistons were placed in plastic casino cups (which seems appropriate), then the Piston Kleen was poured in to cover each piston, plus about an inch extra to play if safe.  Orison says the pistons should soak for anywhere from two to 24 hours and the solution works best at temperatures from 90 to 130 degrees F and some agitation during the soak.  The ambient temperature that day was on in the mid-80s, so we figured a little extra time would do the trick.

The pistons, all lined up in their Rio casino cups. Each piston was covered with Piston Kleen and an inch to spare.

After about six hours of soak time, some of the carbon was starting to come off the pistons, but since we did absolutely no agitation at all, overnight soaking seemed like a good thing.  The next day we checked in on our pistons and were a bit stunned to see that the level of the Piston Kleen liquid had gone down about two inches in each cup!  It was right about then that we recalled Piston Kleen was a water-based cleaner.  With the ultra-low humidity here in Arizona, it should have come as no surprise that evaporation took place.  So to make up for our brain fade, a piece of plastic was popped on and held in place with a rubber band.

Another day passed and we checked the pistons again.  This time, after baking in the sun covered with black plastic, most of the carbon was dissolved.  A small bit of scrubbing with an old toothbrush took just about all of the carbon off, leaving only a few small black smudges.  A few swipes with a fine grit sandpaper got rid of these, leaving the two-stroke pistons looking like new.

After 36 hours of soaking, here's what the first piston looked like.	With a toothbrush, we scrubbed the piston a bit.
We resorted to some fine grit sandpaper to get the last few smudges off.	It only took a few minutes of touch up to end up with a perfect piston.

The piston from the four stroke GS1100 was the worst of the group at the start of test.  It was heavily caked with almost 1/8th of black gunk.  When  the piston was removed, much of the heavy carbon deposits just fell off when the piston was shaken in the cleaning solution.  A few minutes with the toothbrush took most of the black carbon off, leaving only some heavy deposits stuck in the deep recesses of the valve pockets.  Some of these deposits were a quarter inch thick when the piston was put in the Piston Kleen.  A small screwdriver got rid of most of this crud after the soaking.

All things considered, we'd have to rate Piston Kleen highly.  It works as advertised, which is very rare these days.  It cleaned the normal dirty pistons amazingly well and did a great job on the truly filthy GS1100 piston.

Source:

ORISON

4801 South Danville

Abilene, TX 79602

(325) 692-1135

www.orisonmarketing.com