1994 sportster problem

[Sporty8851]

Have good spark on front cylinder but notice weak spark on rear cylinder help

[Sporty8851]

Have replaced plugs wires and coil and same problem

[BlackCloudSalvage]

Just to be clear, did you replace the spark plugs too? Before replacing the wires and coil.

[Sporty8851]

Yes I did

[Sporty8851]

Was thinking it might be the pickup I'm only get 10.5 volts at the plug that goes to the pickup should it be 12volts

[habib]

Have you tried switching the plug wires to see if the problem also transfers to the front cylinder?

EDIT: Have you checked the compression in the rear cylinder?

[Guest]

Have you tried switching the plug wires to see if the problem also transfers to the front cylinder?

EDIT: Have you checked the compression in the rear cylinder?

Check the compression

[BlackCloudSalvage]

To clarify, are you meaning weak spark as in you are looking at the plug sparking while layed against the cylinder and witnessing a faint spark rather than a nice fat spark? Or are you experiencing poor combustion on the rear cylinder and seeing signs of fouled plugs once pulled?

The ignition is a dual fire (wasted spark) type, so the ignition module should not be the culprit since both plugs fire simultaneously every time.

I'd do resistance test outlined by the manufacturer on the coil and plug wires.

Also, you should definitely have 12V at the coil.