Motorcycle Repair: 1977 honda xl 125, honda xl 125, exhaust stroke

Question
I would like to know how to set up the camshaft after it has been out and the sprocket changed. Do the lobes face up or down on the shaft as the "O" on the sprocket is aligned with the mark. please answer if you can.

Answer
Either way, lobes up or fully down will work.  This is what is called a 'wasted spark' engine design meaning it fires on the compression stroke, but also on the exhaust stroke.  So whichever way you put the camshaft in, it will work out fine.  Make sure it is ACCURATELY aligned, not ONE tooth out and take into account the way the tensioner pulls the chain.  

Good luck,  Jan