No worries for the timing disc
To time you bike up is easy, it just takes a little time, a timing disc, a short screwdriver & a length of stiff wire.
1) Attach the timing disc to the alternator side of the crankshaft.
2) Attach the wire to somewhere on the crankcase bent round near the timing disc to act as a pointer.
3) Put the screwdriver down the sparkplug hole (the L/H cylinder is easiest) and turn the engine until the screwdriver starts to lift (at this point I use the bottom of the handle of the screwdriver and a point on the engine as a datum)
4) Rotate the timing disc so it reads zero.
5) Turn the engine in the OPPOSITE direction until the screwdriver gets to the same point again.
6) Note the reading on the disc, take this figure and halve it, this will be TDC.
7) Rotate the engine 38° BTDC and set your ignition timing.
I hope this helps
Webby