Cam to Piston Timing - '76 650

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I'm working on timing the cam to the pistons.
I know that both pistons move in unison but fire simultaneously so there's no question which piston should be TDC, but rather which cylinder should be in its compression stroke when the cam notch is upright.
I first thought to assume it would be cylinder #1, but being that the bike is of Japanese design, it could be #2 for all I know.
Thanks in advance.
 
That's not really something to give any thought to. Just make sure the notch on the cam sprocket points straight up at T.D.C. and the rest will take care of itself.
 
Your close on the way they work. The pistons do move together. The cam lobes that open and close the valves determine which cylinder fires on the up stroke. One cylinder has them 180 degrees out from the other.
This way one cylinder fires then the crank rotates 360 degrees, or 180 degrees of the cam then the other cylinder fires. Thus the label 360 engine.
Thus two sets of points. One for the right side, one for the left.
As 5twins said it doesn't matter which cylinder is #1 or #2. As long as the timing marks line up at TDC when you install the cam with the notch on the camshaft up and the dot on the sprocket by the teeth is level with the sealing surface the cam will be timed right.
If you mistake the marks on the cam you will get it 90 degrees out. Then it won't run.
Leo
 
Yep, that's where things should be alright--IF the PO didn't mess with the sprocket, mill the head, or commit other molestations. You can inspect with a dial indicator and degree wheel or you can line up the marks and trust that things are right. Speaking strictly for myself, I've usually regretted trusting in the competence of others.
 
Your close on the way they work. The pistons do move together. The cam lobes that open and close the valves determine which cylinder fires on the up stroke. One cylinder has them 180 degrees out from the other.
This way one cylinder fires then the crank rotates 360 degrees, or 180 degrees of the cam then the other cylinder fires. Thus the label 360 engine.
Thus two sets of points. One for the right side, one for the left.
As 5twins said it doesn't matter which cylinder is #1 or #2. As long as the timing marks line up at TDC when you install the cam with the notch on the camshaft up and the dot on the sprocket by the teeth is level with the sealing surface the cam will be timed right.
If you mistake the marks on the cam you will get it 90 degrees out. Then it won't run.
Leo

My mistake on the firing of the cylinders, meant to say that they fire alternately and move simultaneously. :doh: Thanks to all for the help in any case.
 
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