Hi: Have timed it numerous times in 30 years, have followed the instructions you give, I made a spark plug
stop years ago, points are opening 35 degrees BTDC.
ET: Engine (Twin) Still Can't Start My Twin, Replaced Mag, But Not A Pop
- Thread starter CarlHungness
- Start date
stop years ago, points are opening 35 degrees BTDC.
You've given us the points opening at full advance, not at the point where you are trying to start the bike. I'd try retiming it to 4 degrees BTDC at full retard. 35 degrees may be great once it’s running but is irrelevant if it won’t start.
The little end is travelling more or less horizontally between 4 degrees before and 4 degrees after TDC so you must find Bottom dead centre using a disc and piston stop then rotate 176 degrees to full retarded firing point. If your ATD has too great a range, full advance timing may mean that you’re trying to start it with the spark after TDC.
The little end is travelling more or less horizontally between 4 degrees before and 4 degrees after TDC so you must find Bottom dead centre using a disc and piston stop then rotate 176 degrees to full retarded firing point. If your ATD has too great a range, full advance timing may mean that you’re trying to start it with the spark after TDC.
You say the spark plugs are dry. I would give a short squirt of brake cleaner or carb cleaner into the opened carbs and give it a try. If it has a spark it should at least fire a couple of times.
Carl, in your last photo I cannot see the central bolt that holds the breaker plate. Its purpose is to connect the breaker with the primary coil inside - as far as I can tell. I am a Bosch man, not Lucas, but even so, same design I guess. Or srew just missing for the photo ?
Vic
Vic
Vic is right. The central bolt that secures the points onto the magneto armature but also provides an electrical connection appears to be missing.
This is what it should look like:
Note the bolt is not any old one and is specific for the job with a taper under the hex head which locks into the points.
The position of the spring clip makes no difference but I notice from your photograph that there is no bolt in the middle of the points to hold them in place and you have an earthing cap. The inside of the earthing cap should contact the bolt in the middle of the points. Assuming that the bolt was only out when the photograph was taken then are you sure that the earthing cap is not causing trouble and have you checked that the points are opening on both lobes of the cam ring? If something is loose or sloppy then it could be that the points only open on one cam lobe.
I take the center bolt out and put an alligator clip in. I hook the other end to the + of the battery. I connect the - end of the battery to the end cap post on the mag. When hooked up the light on the plus side goes on, goes off just as the points open. So I am familiar with the center bolt, have timed it that way for decades. No spark at the plugs at all this time!! Have re-timed it three times, same result.
I take the center bolt out and put an alligator clip in. I hook the other end to the + of the battery. I connect the - end of the battery to the end cap post on the mag. When hooked up the light on the plus side goes on, goes off just as the points open. So I am familiar with the center bolt, have timed it that way for decades. No spark at the plugs at all this time!! Have re-timed it three times, same result.
It bench tests OK. I spin it with my fingers and get a spark on #1..spin it a little faster with a drill-hose connected to front of mag and get good sparks from both plugs..not spinning fast with the drill.