Motorcycle Repair: Honda wont start, honda cb500t, piston rings

Question
It's a 1976 Honda cb500t with 28,000 miles.  I'm looking to buy it. Owner says it won't start because the headlight assembly is not hooked up. It turns over when kicked but no spark.  Is there a kill switch that is connected to the headlight that will hinder/stop the spark?  Do you know the compression for that bike also?  I will check it before I buy it.  I'm sure the bike had gas in it when stored so the carbs will need to be rebuilt.  I have done that before on many small engines.  Will it be much different?  

The bike is also not in good shape.  Surface rust on the chrome and the seat has dry rot on the seams.  I'm handy but not an expert in any way.  I have been told when a bike is over 20 years old, it’s about $1 per CC.  I wouldn’t offer over $200 on this bike.  

Answer
Gregg,

if it has been sitting the compression
will likely be low from lack
of lubrication and/or corrosion
on the piston rings etc.

When in good shape the compression
would be above 150 psi, maybe 170 or so.
It needs 130 psi or up to run very well.

The no-spark is likely due to either
a dead battery or the contact points
under the cover at the top left
side of the engine needing attention.
Two screws hold the cover on.
May need an impact screwdriver or
maybe tap on the handle as you turn
the screws with a good screwdriver.

Carbs will be gummed up with gas varnish for sure.
They are not that hard if you take your time
and clean them really well.
Just jets and needles and lots of small
holes to check.

These bikes were a replica of the older
CB450 twins. They changed a few details
and sold it for a few years.

It needs a good battery to start and
also there is a stop/run switch
on the handlebars.
Check for power to the coils or
points and clean the points.
Try some wd40 or carb cleaner
in the carb mouths, see if it fires
on that.

If you have no power to the coils or
points, check if the ignition switch
is connected and any fuses you see
are ok.