Oil in points housing and dynamo,so replaced mag pinion oil seal.
Having some difficulty getting the ignition timing correct.Setting points opening at the correct time (11mm BTDC) and re-fitting the mag pinion,the timing moves due to the mag shaft turning as the nut is tightened.
Have wedged the points in position with a piece of wood,but invariably they move a whisker putting the timing out.
Would it be better fitting the mag pinion and then setting the timing? Would the timing then be 'nearest tooth?
Am I missing a trick here?
Advice appreciated, Thanks.
This is a very common problem. perseverance, patience and luck are required.
http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1227799&cmd=show
http://wdbsa.nl/ignition_timing.htm
good luck!
The method I use to set the timing is to firstly get the piston to 7/16" BTDC then set the magneto points to the point of opening. I then screw the mag pinion extractor tool into the magneto pinion with the centre screw backed off so that it can't contact the magneto shaft and fit the pinion onto the shaft. I can then hold the points in place with my left hand and with a light tap with a hammer on the end of the pinion extractor knock the pinion onto the taper. I now check that the timing is still correct before tightening the pinion nut and since the pinion is already firmly on the taper it doesn't move when tightening. I check again after it's tightened to be sure.
I have an old earth brush holder with a bit of dowl in so I can lock the mag armature in place once I get the points right. Not too tight as I don't want to bend it. 1 1/2 thou feeler to set the points to just opening. Go past the set point on the piston (pencil in plug, then rotate the correct way to cope up to the set point (7/16 BTDC?) as this gets out some of the backlash. As Derek say above, tap the pinion on to get a lock on the taper so it doesn't move when you do the nut up. Resist all temptation to hold the points as this is how they get broken.
Expect to do the whole thing several times!
Double check you havent been sold a metric oil seal. They are a fraction deeper. It is just enough to stop the gear actually locking onto the taper.
Quote from: limeyrob on 15 Jan, 2026, 13:16 Resist all temptation to hold the points as this is how they get broken.
I only hold the points while I tap on the pinion
not when tightening the nut. Using a dowel in the earth brush holder is a good idea, unfortunately I don't have a spare brush holder.