Motoscrubs.com

I need some advice on the points fitted to my Mototrans Strada please. I've just set the ignition timing, but have two areas where I am a not sure what is happening. Not having worked on an engine with points for 40 years, I am unsure of what is going on.

Firstly, using the light bulb method, the bulb does not go out when the points open, only dim. Does this mean that the insulator on the points pivot is damaged and not properly insulating?

Secondly, to get the points to open at 10 deg, I've had to rotate the back plate fully in the slots and open the points gap up to 35 thou, which is obviously not right.

My points assembly is diametrically opposite to the diagram in the Ducati literature, ie the points are on the left and the condenser on the right, is this correct for a Strada, or is the backplate fitted 180 degrees out?

Any advice would be appreciated.

Colin

The Motoplat points fitted to the Strada are on the opposite side (LH rather than RH) to the Italian bikes.
It is not possible to fit the points back plate the other way round as the slots for the mounting holes are not at 180 degrees to each other.
At a static timing of 10 degrees you are going to get approximately 36 degrees full advance, as the Spanish auto advance is rated at 26 degrees.
You could try retarding it slightly as the handbook for the Strada says 34-36 degrees fully advanced.
Equally, you could open out the mounting slots a bit to give yourself a bit more adjustment.
The points gap should be 0.35-0.40mm which is roughly 14-16 thou.
Your indicator lamp should go out completely once the points open, so the insulation may not be perfect.
Have you taken the points off the back plate and cleaned them up? That would be my first step.

Jon

Thanks Jon,

I did give the points assembly a cursory clean, but as I intend to change to electronic ignition eventually, I didn't bother too much. I will have to have another look and see if I can improve them. I suppose that the points could be the originals, so they are 40 years old. Thanks for your help, at least I know that that the back plate is not fitted 180 deg out.

Maybe the capacitor has bad isolation. You could check this by disconnecting.

..

Ok thanks Hans.

Well I've set it, but I'm not particularly happy. Took off the points and stoned them, although they weren't in bad shape, and reset the gap, and cleaned everything, but still could not get the light bulb to go out when the points open, only dim. Disconnected the condenser and that made no difference. Opening the points manually just results in the bulb dimming.

I found it really difficult to hold and bring the engine to 8 deg btdc, because it appears to be at a point where the alternator magnets want to pull the crank either forward or back, so as I rotate the engine, as it reaches 10 deg btdc, the crank suddenly turns over to about 20 deg after. Hopefully it will suffice so that I can get the engine running initially.

Interested to know how you have the bulb connected.
When I connect a bulb from the batttery + to the points spring (with the ignition off), the bulb goes right out when the points open.

I have the same issue when trying to set the crank position.
I might try doing it with the bike in gear and the back brake slightly binding.

Same as you - power taken from battery + and then clipped to points spring. All the insulating washers are in place but something is wrong as the points spring is earthing through something. Possibly the fibre washers are contaminated with oil?

I am used to working on v twins, where the other piston holds the crank in position. I cannot remember if I ever timed a Ducati Single in the past, as my mk111 350 and 450 had Motoplat ignition and I don't recall ever timing my Sebring, but it was over 40 years ago.

Do you have the Ducati reg/rec? Does your bike have an ignition warning lamp?

I ask because some wiring diagrams show the + side of the ignition coil being connected to the r-r via a bulb to the brown wire, to act like a charging check lamp. When the engine isn't running, and the ignition is switched on, the brown wire provides a return to ground through the bulb, lighting it up. When the engine is started, power is fed to the brown wire and the bulb goes out.

You could try removing the wire from the coil to the points, and test again.

There may be a situation whereby there is a current path from the battery, through the test bulb, then through the coil, ign warning bulb, brown wire to ground; hence a dimmer test bulb.

Incidentally, the w/shop manual I have (not for the Strada) states in the procedure for checking the timing;
'Rotate the crankshaft slowly anti-clockwise till the light goes out, or loses its light intensity.'

Worth a try I guess, there may be nothing wrong.

Forgot to mention;

Secondly, to get the points to open at 10 deg, I've had to rotate the back plate fully in the slots and open the points gap up to 35 thou, which is obviously not right.

I had the same situation. I filed the heel of the sprung bit (the bit that rubs against the cam) until I could achieve the 12 -16 thou gap required. Then I could set the timing with the slots in the middle of their adjustment range. At 35 thou the dwell will be all wrong potentially resulting in a weaker spark at higher revs.