Clean engine interior with MMO?

[HalfCentury]

The bike is running on the center stand with Dyna DC1-1 coils zip tied into place. I am suspecting carbon build-up causing an apparent uneven balance condition. The carbs are balanced and the plugs are not fouled. Plug #2 center ceramic portion is 1/2 white and 1/2 medium brown. I think that maybe the combustion chamber has uneven carbon buildup.

What is the prevailing wisdom concerning running Marvel Mystery Oil in the crankcase and/or gas tank to reduce the carbon build-up?

The plan is to get the bike back together and run it locally with MMO as often as possible to see if that will improve smoothness of the engine.

[DiverRay]

Easy way to get rid of carbon buildup.
1. with engine warmed up, pull all 4 spark plugs, put about 2 ounces of Berryman's B12 Chemtool into each hole and replace plug, but only turn about two turns to keep things out/in.
2. After about 20 minutes, pull plugs, turn bike over two or three times, and replace plugs.
3. Start engine and rev it a bit once you have oil pressure.
You should see and smell the exhaust at first, but it will clear out after about 5 minutes.
Carbon SHOULD be cleaned out WITHOUT the chance of burning a hole in the piston. MMO in the oil will NOT get into the combustion chamber in quantities needed to clean it. The other way is to have it running with air filter off, and spray water into each carb as it's running. Problem with that is you CAN burn a hole in the piston if done wrong.

[HalfCentury]

Hi Ray

Thanks for the procedure. The B12 is now sitting in the warm cylinders. Will advise after the remainder of the procedure.

[HalfCentury]

The procedure is complete. It required a long time of cranking to get the engine to fire.

After running a couple of minutes, I added some B12 to the tuning bottle and ran it at 6k for a bit.

Plug #2 is now clean. Woohoo!

Much re-assembling to do before it goes on the road. I will post some results after a road test.

[DiverRay]

Yeah, my dad and grandfather used B12! I've used it the 50 years I've been wrenching.

[HalfCentury]

The remainder in the container seems to do a good job of removing the fouling from the fouled plugs.

I bought two containers of the B12. They were on special for $4/12oz. Some of the unopened container will be used with the first tank of gas when the tank goes back on the bike.

[DiverRay]

Good price!
You can also put a little in the oil just before a change. With the bike warm, add about 4 oz. to the oil and idle for about three minutes then change the oil. DO NOT DRIVE THE BIKE with the B12 in the oil!! IT will help soften the seals and take the gunk out of the inside of the cases. I've used it quite a bit for that when I get a "new to me" machine.

[HalfCentury]

Good price!
You can also put a little in the oil just before a change. With the bike warm, add about 4 oz. to the oil and idle for about three minutes then change the oil. DO NOT DRIVE THE BIKE with the B12 in the oil!! IT will help soften the seals and take the gunk out of the inside of the cases. I've used it quite a bit for that when I get a "new to me" machine.

I will do that. Thanks for the tip. I planned to change the oil after re-assembly anyway.