Originally Posted by todehnal
Now to use it: You will need a bicycle tire pump, a couple of rubber gloves, a 3 or 4 foot length of plastic tubing about 1/4" size, a couple of old shop towels and some mineral oil or baby oil will work just as well.
I popped out both carbs and replaced them with the rubber gloves to seal the intake ports. I cut off one finger tip and inserted one end of the plastic tubing into it and clamped it with a hose clamp. The other end was pushed tightly over one of the valve stems. I attached the tire pump to the other rubber valve stem. Wrap a few old shop towels around the tip of the soldering iron and soak them very well with the mineral oil. The soldering iron and old soaked rags go ito the jar and close the lid tightly. Now plug in the soldering iron and wait about 5 minutes while the jar fills with smoke. Start slowly operating the tire pump and watch the rubber gloves inflate. After a few minutes you will see smoke if you have an intake leak.
A friend brought over an automotive smoke generator and we hooked it up on my 912. I removed the left carb, (the side I suspected a leak) and plugged the boot. Then removed the crossover tube and inserted the smoke into there. We never saw smoke come out and suspect it was getting past the piston rings.
I know I could removed the intake manifold from the head and blocked it there but didn't want to go to that extreme.
How did you prevent the smoke from passing through the engine?