Look for oil on the points, Those bikes are known to lose the seal on the end of the cam where the advance unit mounts. Also always set the timing fully advanced. Those points should be adjusted regularly. There is an upgraded Lucas timing plate available for those too that does away with the stupid eccentric adjustments. Also I always had best luck running AC R45XLS plugs, those things will burn dirt. If by chance the seal is bad you will need a small slide hammer to remove the advance unit that is made for that task it is on a taper. The later models have an index on the taper and in the cam making replacement much easier than the old smooth ones. The seal can easily be pulled out with a small hook and new one pushed back in but be careful not to roll it. There is a hole at the base of the jugs above the trans, that is where the timing plunger goes. The plunger drops into a hole drilled into the crank, there are 2 and you want the firing position hole not the TDC hole. Time the left side first then the right, again fully advanced. Pull the plugs and get the rear wheel off the ground ,put it in high gear, rotate the engine by the rear wheel watching the valves when the intake opens start feeling the timing plunger for the index. That bike should start every time on one kick if timed and everything is adjusted right.
