The BSA A7-A10 Forum

Technical => Lucas, Electrical, Ignition => Topic started by: fido on 24.04. 2011 13:44

Title: Auto Advance
Post by: fido on 24.04. 2011 13:44
A friend has a plunger A7 and has recently had the magneto rebuilt. He seems to have had trouble getting the ignition timing right so I went to help him with it yesterday. I got the timing close enough to run OK, although it was slightly advanced. I know from experience that you are lucky if you get it spot on but these engines are not that fussy about the odd couple of degrees either way. The first thing I noticed was the advance unit would stick on full advance, there seems to be slight resistance that is not overcome by the springs. This sticking was worse when I fully tightened the pinion to the magneto shaft so the bolt seems to be somehow removing the clearance for the bobweights. Has anyone here experienced this problem and found a solution? We didn't have a lot of time but we failed to get the bike started, I'm hoping due to the advance unit problem.
I personally prefer the manual advance magnetos like I had on the A7SS.
Title: Re: Auto Advance
Post by: Stu55Flash on 24.04. 2011 22:11

The clearance of the auto advance is set by the pressed on ring at the rear of the auto advance unit. Press it on too tight and it will not move freely.

Title: Re: Auto Advance
Post by: fido on 25.04. 2011 07:42
Thanks Stu, I see you also have a FB Falcon. That was my first classic bike and first restoration back in 1977 but mine was a 1956 model. I never had a workshop manual so  the ignition timing on that was pure guesswork! I eventually found a manual that covered my 8E engine which was actually for the Bond Minicar but the bike had been passed on by then.