Decarbonizing without disassembly

Nice tip!
Thanks.

water sprayed into the intake will decarbon the engine just don't get to western with the water spray and keep the rpm up. Real uncooked rice will clean the combustion chamber but I've never tried it its supposed to spit out jet puffed rice out the tail pipe I've heard of this on 4 strokes mainly not real sure on the 2 strokes like we run stuff will get into the bearings so its not a good idea on industrial 2 stroke it might work where the crankcase is seperate from the power cylinders. STCIK WITH the water.
Norman

Norman, be very careful with the water method, use only tiny amounts at a time a minute apart. Too much water will blow a hole thru the jug or break a connecting rod. Ive replaced many marine engines where the customer heard this from someone and put a bit too much water in their engines. We use generic combustion chamber cleaner from NAPA, it works for a little while but its only a temp cure. Its the same stuff as the OMC combustion chamber or Bombadier cleaner but a lot cheaper.Mac

so far I have not needed to decarbon one

Its an old mechanics trick to use water to decarbonize the combustion chamber, it works by turning the water into steam which then scours away the carbon, it does work on larger automotive engines with large strong pistons and cylinders. The problem is if you put a little too much in too fast in smaller engines the water will not get a chance to turn to steam and fills up in the combustion chamber then when the piston comes back up the water will not compress and it blows out the cylinder wall or breaks the connecting rod and that in turn will also punch out the block too. Now I am talking that this is what happens with 4-6-8 cylinder 4 stroke automotive and marine engines, but with small 2 stroke engines it may not do any damage as water will blow out the exhaust port before it gets compressed and still would not have a chance to turn to steam.

How do you know when you need to de-carbonize your engine? I did a lot on cars when they developed a carbon knock by pouring transmission fluid thru a running engine. It will smoke for a long time though.

I have yet to see the need for decarbon one of my engines. I've only decarboned my Harley long ago and a Honda goldwing using water and keeping it rebed up I'd spray a mist into the intake. I once tried to unstick a valve on my car with tranny fluid in the intake and it would help for a while but I soon got rid of the car.
Might be a good idea to take these engines apart to decarbon them if you think it need it done and not use water or rice or etc. the commercial products might do a good job but I have not tried them.
the rice thing was used on industrial 4 strokes and I was told about this by a friend who said it will make the combustion chamber clean as a whistle but be ready for flaming particles of rice coming out of the exhaust stack and be sure to remove the muffler.
norman

Old Motorbike, you answered your own question, carbon knock is the result of carbon buildup on the valves of 4-6-8 cylinder engines, also carbon buildup on piston crowns is really bad too as the carbon thats sitting on top of the piston gets red hot in the combustion chamber and burns a hole thru the top of the piston.The best way to clean it is to disassemble the engine, but thats not practical in most cases unless you are disassembling it anyway for something else. The only real easiest way to tell if you have carbon buildup is to check your plug and shine a light into the spark plug hole.

I once made a water decarbonizer out of a bike water bottle and some fish aquarium stuff. It worked very well on an old Honda I used to drive around. I believe it was a 77 model that had points and a coil. (no CDI in those days)

The parts I used were a brass adjustable feed valve to regulate the amount of air and one of those cylindrical stones that makes a foam of bubbles. I had some plastic tubing and toothpaste size tube or RTV to seal this stuff with.
The stone was plugged into some tubing and a hole drilled in the flat sealing cap to pull it thru so the stone sit in the bottom of the bottle. The brass valve was RTVed to the lid and the tubing connected to one nipple. The other nipple had a small air filter I made for it stuffed with fiberglass. (all this stuff was fish aquarium parts) Then a larger hole was drilled thru the cap for a larger piece of tubing.....which would go to a vacuum tube to the carb. I cut that tube and inserted a windshield washer tubing "Tee" and plugged the tubing from the bottle
to it.

When I started the motor and allowed it to idle I barely backed out the adjustment screw till the water in the bottle began to bubble. It wasn't enough to effect the idle rpm and it was the setting for the operation I needed. This dampened the air going thru the bleed and was enough to
do an excellent job of decarbonizing the motor.

In time a head gaskett blew between two cylinders (this 1600 cc aluminum head motor was famous for this problem and was recalled numerous times)
The mechanic that fixed it for me asked about the little decarbonizer bottle
and remarked on how clean the head and piston crowns were. I was working loads of hours then and living in an appartment and had to farm out the repair.

I found a Radio Shack CDI unit in a yard sale and installed it on the motor later. The odd thing was that even with resistor plugs....when I used the decarbonizer bottle it would slowly cause the outer electrode of the spark plug to thin. If I turned off the water bottle it didn't happen. But when I ran the water bottle the plugs came out clean as the day they went in.

So, I would guess for a MB that one of these could be set up and fitted like a "boost bottle" to dampen the intake air. I won't speculate on the long term
effects of using this thing on the bearings.