Ignition timing has slipped (for the second time)
Found the magneto is very stiff to turn by hand.I used to be involved with homebuilt aircraft which used a VW beetle engine with two Lucas SR4 mags and the mag specialist I used was Dave Lindsay of Heywood lancs.
That was many years ago and he will no doubt be retired or deceased.
Don't feel confident enough to strip the mag myself so can anyone recommend a good mag specialist?
There only seems to be one who advertises in the club magazine,Priory Magnetos.
Priory Mags are based near me in Macclesfield and i can highly recommend his work, no doubt others can too.
Have a look over on https://www.a7a10.net/forum/index.php for more recommendations.
How does it keep slipping ? The magnets in the body can make turning over by hand difficult sometimes .Does the unit produce a spark on the bike ?
It most definitely should not be stiff. Could be dry bearings but it may also have overheated and bled wax into the gap between the armature and the case. This can make the mag very stiff as it acts like glue. Worth getting it sorted before it gets worse.
Thanks for the replies.Went for a good run and everything was fine.A week later on starting spitting back through the carb and although starting ok, it wouldn't keep running because of the spitting back.
Checking the ignition timing found it well retarded.Took the mag off this time, (this has happened before) and found it very stiff to turn.The mag shaft looked scratched.I am guessing the bearings are corroded or the grease has solidified as before I bought it it had been standing for many years.
Whatever,it needs a specialist to overhaul it. Thanks again.
APL magnetoes shaftesbury Dorset. He has overhauled many mags for me and actually manufactures many of the armatures that other companies use.