Motorcycle Repair: Yamaha DT400 timing, retarded timing, engine case

Question
I've got a 1976 Yamaha DT400 and I'd like to check the ignition timing. Can you help?

Answer
Tom,

-the timing can be checked with a timing light
on the flywheel. There is usually some
timing marks on the flywheel (magneto)
and the engine case. If there are two
marks on the flywheel, the left mark
is advanced timing, when the engine is
sped up, the second or mark further
to the right is idle or retarded timing.

-If the bike has points, they may need
to be replaced or at least filed, sanded
and cleaned well.

-They should just break open as the right or
idle timing marks align.
-
If no marks exist, a dial indicator
would have to be used in the spark plug
hole to find the right piston position
for setting the timing.
A dealer should have that.