One tooth off?

I recently bought a 1975 XS 650, not running very well. When setting the ignition timing, the only way I could get the points to start to open at the F timing mark was to rotate the points backing plate to the stop in one direction and set the point gap at the minimum, 12. It is hard starting which could be a carburetor issue. I have adjusted the cam chain tensioner and the tappets. This seems to me to be a situation where either the engine was taken apart and the cam not set right or the tension was too loose and the chain skipped a link. Does this sound like a reasonable theory to any of you who might be reading this? Thanks in advance for any input.
By the way, I also serviced the centrifugal advance and made sure it sprung back easily.

Welcome to the site. How does run out on the road after you get it started. Put a timing light and see where its firing. Not familiar with points. If the chain was run loose and out of adjustment it might need replaced.

Once it is running it runs fast with plenty of power. I'll check it with a timing light, but like I said the static timing is at the limit.

You can also try this to check cam timing http://www.650motorcycles.com/CamTiming.html

Thank you for that link!

The beauty of doing a teardown is worth the peace of mind.

Well if it runs strong it is not a tooth off. Checking with a timing light is the best way to tell if is over advancing and initial. Back to the carbs pods on or off. Take the pods off see if it runs better. Straight pipes or mufflers. Just because the carbs worked on one bike doesn't mean they are jetted right for another. Get the timing set. Clean the carbs you are going to use Record the jet and needle information. Some pictures of the bike we like pictures.

In my experience if it was a tooth off you wouldn't be able to get that thing over 60. I have ridden a 650 that was a tooth off and it was a hard start and when running had to be going downhill and pulled by a truck to get it above 55mph.

So I am leaning on other things. Maybe shitty valve seals, timing, carbs, voltage etc. . .

One tooth off=20* of crank rotation in a 447 motor and a bit more than that in a 256, so checking is pretty simple. In a 447 motor, the intake valves should just begin to open (tappet should close) at 36* BTDC (a little to the right of your advance timing mark) when the tappet is set at the .012" inspection clearance (if you have a 256 motor the inspection clearance is the same, but you'll have to look up the IO event). Set the left intake valve to the inspection clearance, slip a piece of cellophane between valve stem and tappet, turn the motor until the piston on the left cylinder is rising on compression, and feel for the moment the tappet grips the cellophane; it should happen fairly close to the advance timing mark. For reference, the distance between the advance timing mark (40* BTDC) and the midpoint of the F marks (15* BTDC) is 25*.

When you run out of timing adjustment on the advance side, it usually indicates that a new cam chain is needed.