I'll stick my neck out here since I'm not that familar with the A3 ignition.
On the A1 A2 models, that part is referred to pulser coil timing advance rotor which is a 2 part item witha spring . As the RPM's come up the rotor mechanically advances to increase timing advance.
On the A3 item #19 is referred to a timing pulser rotor.
In the supplemental manual, the ignition diagnostic page 326 it suggests that if the timing is off at idle to look for either pick up coil damage and replace or ignitor damage to be replaced if the pick coil is not damaged. If the high speed timing is off and no pick up coil damage, to replace the ignitor. That suggests to me that the timing advance in the A3 model is electronic and built in to the ignitor.
On page 324 of the manual this is written The timing rotor is mounted on the crankshaft through
the starter motor clutch by means of a positioning key.
The rim part of the timing rotor has two holes 45
degrees apart from each other, and runs between the
Hall IC and the permanent magnet. When the metal part
of the rotor is between the Hall IC and the magnet, the
magnetic field developed by the magnet is intercepted
I think you need to pull the rotor and find out where the slop is in that mount. If the rotor is keyed, then there should be no movement between the starter clutch and the rotor , I would think
First, Thanks for the great pictures here and sharing. I think this is the 3rd time in 4 years I've seen reported loose screws between the clutch hub and the torsion damper.
I have a couple of concerns here.
1st- You mentioned that the key between the torsion damper hub and the crankshaft was chewed up. That would suggest some movement between the 2 and there shouldn't be. Correct me if I'm wrong, but that torsion damper is a tapered fit on the end of the crankshaft and if that's the case, the purpose of the woodruff key is to time the damper to the crankshaft which would also have an effect on the timing of the pulser rotor to the crankshaft. I would be doing 2 things here.
Replace the woodruff key (1/2 moon shaped key)
Lap the taper fit of the torsion damper to the crankshaft. Couple of dabbs of extra fine valve lapping compound on the taper of the hub and place on the end of the crankshaft without the key and rotate back and forth to lap the hub to the crankshaft. Couple of minutes should lap those 2 in nicely. Clean everthing up well and they would be ready to install.
2nd- Have another look at that torsion damper hub. Item #28 in pic. They called it a torsion damper which suggest that it absorbs some torsional pulsing between 2 parts which suggests to me that the damper is a multi piece item. Quite often damper hub have an elastomer (rubber) vulcanized parts within to absorb vibration. If the 3 - 8mm X 25mm socket head cap screws were loose, that may have had an effect on the damper aspect of the hub.
Appears to be a misunderstanding. The Damper to Crankshaft is Tight no slop. Its in good nick.
Pulsing rotar coil/Timing plate to dampener is a bit chewed out. Gonna stick a timing light on it and see where its at. In an ideal world I would get a new one but seems this is a rare component.
If the damper to crank is tight, how did the key get chewed up? Usually when a keyed hub is loose on a shaft, the hub will shear the key or chew it up.
Is this pic the back side of the pulser coil ? If it is, then it appears that the rotor locates itself by the bore on the dogs of the clutch. Looking at the bore of the rotor in the pic, it looks like the bore is chewed up a bit at the ear at 5 o'clock and the ear at 10 o'clock. Now I'm concerned that the rotor will be out of true with the crank. Pulser coil to magnet clearance is usually in the .008"- .015" to ensure a strong magnetic presence. Not sure just exactly how I would go about fixing the damage without having the parts in my hand. Just thought that it might be worth mentioning.