No spark

[Davetiler]

Rebuilding a sports arrow
Before fitting everything back ,tank etc,I want to run the engine,but can’t get a spark
Ignition switch faulty ,bypassed with a straight on and off switch
Bypassed the ammeter
Put a multimeter on condensers and they appear to be ok
Put another pair of coils on ,no spark
New battery
Help got no ideas left

[Paul_Linden]

Sounds like the points are shorted to earth.

[Davetiler]

Points shorting to earth
Something to check ,difficult to see how
Dave

[will_curry]

The moving points are the ones connecting to the coils.

First check is that the points gap is correct and that the points are opening
and closing as the engine turns.

Next, disconnect the points from the coils: two wires, one black and white and one
black and yellow. With the points closed there should be continuity between the appropriate
wire from the contact breaker and earth - the primary chaincase should do nicely for earth.
With the points open there should be no continuity.

When putting this contact breaker assembly there is a number of fibre washers which
have to be in the right place for things to work.

Another, more basic, test is to touch the live ends of the leads from the coils onto
the primary chaincase with the ignition on. This should be enough get the plugs to
spark if the only problem is the contact breakers.

[Davetiler]

Ok got it running but one set of points arcing badly
And oil dripping from one cylinder