EvanB (Forum Supporter)
EvanB (Forum Supporter) MegaDork
9/16/20 3:26 p.m.

I am trying to get my Ducati scooter started but have no spark. I have tested the wires for continuity to make sure there wasn't one going through the frame that was chewed by a mouse, all seem fine. The coil ground tests good and I have ran a separate ground wire to the engine from the frame with no change. The points open, there is continuity across the points open and closed but a thread I found on a Ducati forum with the same issue said that is normal when everything is working correctly. 

From what I can find there is no ignition switch, just a kill switch to shut the engine off. 

Here is the ignition section of the manual that I was able to find. 

What else should I test?

iceracer MegaDork
9/16/20 6:40 p.m.

My experience with tractor mags, the most common fail was the coil.

TurnerX19 SuperDork
9/16/20 10:45 p.m.

Do the magnets still have magnetism? They can fail do to storage condition.

EvanB (Forum Supporter)
EvanB (Forum Supporter) MegaDork
9/17/20 10:12 a.m.

The magnets still have magnetism. I'm not sure how strong they are supposed to feel but they definitely attracted the few various parts of steel I tested against them. 

CJ (He's Just an FS)
CJ (He's Just an FS) HalfDork
9/17/20 4:25 p.m.

I have a couple of Harley lightweights so I am on a couple of lightweight boards.  Some lightweights have magnetos and I have watched several in the lightweight groups struggle with their mags. 

Mutt Hallam is the guru of all things Harley and has set most of these folks on the right path to a hot spark.  I believe that he has the equipment and expertise needed to make your mag work properly. 

I think that I would shoot him a message and see what he thinks.

His email is "pigstye13 at aol dot com"


noddaz UltraDork
9/17/20 5:46 p.m.

Did you disconnect the kill switch and try it?  If the kill switch was shorted it would keep the ignition off.  Next step to me would  be to swap the condenser out with a different one in case it is shorted to ground.


EvanB (Forum Supporter)
EvanB (Forum Supporter) MegaDork
9/17/20 5:55 p.m.

The kill switch is currently disassembled. 

After messing around tonight I thought maybe I had found it. I took off the spark plug lead and it wouldn't register anything when trying to measure resistance. After looking at it a bit the part that clips onto the plug screws into the boot to contact the wire that goes in the other side of the boot (90° boot). It was loose so I tightened it down. Then it measured resistance, although I forgot to look at what it read. After putting it back together, still no spark. 

I'll have to go back at some point and see exactly what resistance it has. I have been thinking swapping the condenser, I may order one and pull the flywheel to try that next. 

It had spark and was running before it was parked 16ish years ago. I'm not sure what else other than the wiring or magnets can degrade in that time. 

RichardNZ Reader
9/17/20 6:47 p.m.

Your diagrams don't specify whether there is an external HT coil or not - eg is the spark plug lead connected back to the mag ? Uncommon but not unheard of ! 

My experience of such systems is that the first point of failure is usually the "condenser" - it is usually safe to disconnect them briefly for testing purposes as their function is to make the points last a bit longer. The second thing I would suggest checking is the points, disconnect them and do your open and shut checks with a multimeter.

My Yamaha (1976 TY175) has what is probably a "similar" system, I'll do some measurements for you later but it means taking the tank off and I have another bike (not mine) having some work done that has to be finished for an event tomorrow.



EvanB (Forum Supporter)
EvanB (Forum Supporter) MegaDork
9/17/20 6:54 p.m.

Yes, external coil. Here is the basic wiring diagram. It is for a Mountaineer rather than my Brio but I haven't been able to find any Brio specific manuals. 


I'll pull the flywheel off next to check things and measure what size condenser I need. I have seen a few for other scooters that look the same but appear to have different sizes. 

RichardNZ Reader
9/18/20 12:46 a.m.

Hi Evan,

this link is for the TY ignition system manual, https://trialsport.com.au/TY175/TY175%20Manual%20Section%206%20Electrical.pdf , there are ballpark resistance figures for primary and secondary coils tucked in there that are probably representative of your system.

Note that the resistance values are all quite small and will need a fairly accurate meter. I'm still reasonably convinced the condenser has probably "dried out" but given it hasn't run for 16 years or so check the condition of the points for oxidation or similar.





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