Honda GL1000 Timing Advance Unit Details

OEM Honda Timing Advance Unit Details:
Honda-GL1000-Ignition-Advancer

This simple device is critical to proper ignition function on Honda GL1000s!

The ignition advancer is a simple, but critical component of the GL1000 ignition.  It’s located behind the points cover on the end of the left camshaft …near the gear shift lever.

It should be checked during routine tune-ups and whenever you experience ignition or carburetor problems.

Why?  Problems with the advancer often mimic carburetor problems!

Symptoms that implicate the advancer:

  • Erratic idle
  • “Hanging” high idle
  • Low power output
  • “Surging”
  • Poor throttle response

Things to Check:

  • Advancer should move freely on it’s captive shaft.
  • Make sure the locating pin is intact.
  • Makes sure springs are installed correctly.
  • Make sure the non-adjustable “Stops” have not been broken by a prior “mechanic.”
  • Make sure the retainer bolt is secure and has the proper washer to permit free movement.
  • Make sure the advancer on your bike matches the engine / camshaft (see below).

Details:

  • Advancer requires No Lubrication! Lubrication is unnecessary and usually “slings” to compromise the breaker point surfaces.
  • The stationary pin portion that allows rotation by the movable portion should have a nice polished finish.
  • Springs lose spring rate over time and require replacement.  Unfortunately, there are no good replacements in the market at this time.
  • Many aftermarket electronic ignition replacements (like Dyna/S) retain the use of the the stock advance unit.
  • Make sure the advancer on your bike matches the engine / camshaft (see below).

OEM Specs / Unit Identification

1975-1977:

  • Static initial timing: 5 degrees BTDC (“F” mark on crank)
  • Full advance: 37 degrees BTDC
  • Centrifugal Spark Advance Unit is marked “371” 
  • Advance unit turns at camshaft speed = 1/2 crankshaft speed
  • Advance unit provides 32 degrees of dynamic advance (at crankshaft)
  • 16 degrees of advance at the advance unit itself

1978-1979: 

  • Static intial timing: 10 degrees BTDC (“F” mark on crank)
  • Full advance: 37 degrees BTDC
  • Centrifugal Spark Advance Unit is marked “431”
  • Advance unit turns at camshaft speed = 1/2 crankshaft speed
  • Advance unit provides 27 degrees of dynamic advance (at crankshaft)
  • 13.5 degrees of advance at the advance unit itself

In both versions…

  • Dynamic advance begins at 1,450 rpms
  • Maximum advance at 2,600 rpms.

Comments

  1. Greg Spohr says:

    Good morning. Great to find your website. I now live in central America where it’s always summer and all those beautiful winding jungle roads have no traffic cops.
    There is a good looking 1977 GL 1000 for sale a few hours away. Paint, mufflers, plastic, everything, all original.
    Naturally I am curious about parts availability for a bike that’s basically older than God. I will be riding it lots.
    Before I buy would like to hear what sort of assistance (parts and maybe advice/info) you could provide.
    All comments welcome. Thanks.
    Regards….G Spohr.

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