Greetings!
I'm new to the forum, and to old Cats. About three years ago, when I moved west, I bought a bunch of land and a 1948(?) Cat 12 Road Grader. It ran when I bought the place, but time got away from me and I haven't run it since 2005. I went to fire up the pony motor this spring, and I ran into two problems.

First, no spark whatsoever.
Second, the carburetor seems to be flooding the once cylinder.

Reading around it seems the second problem can be fixed by tearing apart the carburetor and working on the needle valve. Is accurate? Can anybody provide specifics?

As to the first problem, I seem to have made it worse, in that I took the cover off the magneto and removed the rotor, without paying attention to how it was oriented. Thus, not only do I need to get spark, but I also need to figure out how the rotor should be oriented. The magneto is a Wico, but it only has a Cat part #4S6469, so I'm not sure exactly what it is. It looks like some more modern version of the XH units I've found on the net. It has a little red mark on the side, but I can't find any particular thing to align it with inside the housing. Any tips on getting some fire and getting it timed right? If I turn the fly wheel by hand, I get the nice "pause -- snap" that I'm supposed to get, but no spark. (I've tried new plugs, I've also tried a wire close to the frame.) That leads me to think it's a points/condenser sort of thing rather than a mechanical problem.

I'm really looking forward to getting this monster going.

The serial # is 9K9722 if that's helpful, or if someone can confirm the year of the machine.

You will probably find that there's a lot of trash/rust in the pony motor tank and some has gotten into the needle of the float valve that keeps the carburetor bowl full. The top of this bowl can be removed and the float and it's needle and seat can be cleaned and checked.

To get the spark back, probably you need to file the points and set the gap to about 0.020" gap, but first make sure the switch is on and that isn't the trouble. data I found says XH1908 is the Wico mag on the D4600 engine pony motor. There should be a "mag" mark at about 30 degrees BTDC on the pony motor flywheel and a pointer near the 12 o-clock position over the flywheel. Open the cylinder petcock on the cylinder next to the controls (right side of a grader) and turn the flywheel of the pony until air rushes out of the petcock to find compression stroke of number 1 cylinder (the one next to the controls). Turn on around until you line up the mag mark and then see what you have to do inside the mag to line up the rotor with the plug wire terminal on the cap. If you turn the flywheel slightly past the TDC point, the impulse should trip and the points should open and a spark is generated. When your engine speeds up, a centrifugal mechanism locks the impulse out and the timing is advanced to make the engine run better.

Your grader was made in 1945 at the end of the 9k series.

Thank you! This is very helpful.