Small Engines (Lawn Mowers, etc.): B&S 20 HP V-twin Mower Engine, crank case, manul

Question
I got a free mower/tractor that broke a connecting rod. I took off the crank case to get the broken pieces out and replace the oil flinger. How do i line up the camshaft to the crankshaft? The Crankshaft gear has 2 dots on it. The Camshaft gear has one dot and roman numerals I & II ...each repeated once and i think 180 degrees from each mate. Do i just put the one dot between the 2 dots...that seems too easy...what are the Numerals for? Thanks so much!!!

Answer
I check the manul and it did not mention 2 marks on the crank gear.I would line the dots the way you described but before buttoning up the bottom end I would install the heads and follow the valve and piston travel.  Make sure the intake valves open approximately on the down stroke, close as the piston travels up and are closed at TDC.  Follow the exhaust as well.  The valve should open as the piston starts to trave up.

Are you familar with valve overlap?  At TDC, both valves will be just slightly open.  You may have to feel this as it is difficult to see.  All 4 cycle engines, when properly timed, will have valve overlap.

Let me now if this helps.
Eric