Automatic Advance and Retard Unit Springs for 650cc Twins

The pair of automatic advance and retard unit springs currently fitted to the TR25W machine is Lucas part number 54417992.

These springs are stronger than those presently fitted to the IBI Range 650cc twin models.

The use of these springs will reduce the rate of ignition advance. This will improve low speed running and can eliminate a 'ping', or 'spark knock' symptom.

Install the stronger springs as follows:

  1. Disassemble the auto advance unit.
  2. Thoroughly clean off all the originally used dry lubricant. This is important. as any other type lubricants will not mix with the original dry lubricant, and the result will be a non-working auto advance unit.
  3. Lubricate the spindle. pins, and counterweights with Delco Remy #U -1901 Distributor Cam Lubricant or a graphite base lubricant such as Dri-Slide.
  4. Reassemble the unit. using the stronger tension return springs - #54417992.


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