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techtalk:evo:engctl01 [2019/08/07 02:13]
ixl2relax [Electronic Ignition Systems]
techtalk:evo:engctl01 [2019/09/16 01:32]
ixl2relax [IGNITION TIMING - All Models Thru 2003]
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 ===== VOES - Vacuum-Operated Electric Switch ===== ===== VOES - Vacuum-Operated Electric Switch =====
 +===== Sub-Documents =====
 +  * [[techtalk:​evo:​elec01a|Dissecting the Voes]]
 +
 +----
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   * The VOES was first installed on Sportsters in 1983 (and used on most models thru 2003). The unit senses intake manifold vacuum at the carburetor and requests that the Ignition Control Module (ICM) switches between one of two different spark advance curves. The switch is closed at high vacuum operation, utilizing a more advanced spark curve and it is open at low vacuum operation, utilizing a less advanced (retarded) spark curve to minimize engine knock and still maintain performance. The VOES is installed above the intake manifold. ((1959-1985 Clymer Sportster Repair Manual pg 230))   * The VOES was first installed on Sportsters in 1983 (and used on most models thru 2003). The unit senses intake manifold vacuum at the carburetor and requests that the Ignition Control Module (ICM) switches between one of two different spark advance curves. The switch is closed at high vacuum operation, utilizing a more advanced spark curve and it is open at low vacuum operation, utilizing a less advanced (retarded) spark curve to minimize engine knock and still maintain performance. The VOES is installed above the intake manifold. ((1959-1985 Clymer Sportster Repair Manual pg 230))
  
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 To set the timing **dynamically**,​ first, remove the timing plug & install the clear timing hole viewer plug (It MUST NOT touch the flywheel). Connect the clamp of an inductive pickup timing light (powered by the battery) to the front spark plug wire. This will allow you to 'shoot the light' into/thru the clear viewer plug. Then start the engine, set the idle at 1000rpms & shoot the light into the timing hole. Move the timing plate so that the 20° advance timing mark shows up in the center of the timing hole. To set the timing **dynamically**,​ first, remove the timing plug & install the clear timing hole viewer plug (It MUST NOT touch the flywheel). Connect the clamp of an inductive pickup timing light (powered by the battery) to the front spark plug wire. This will allow you to 'shoot the light' into/thru the clear viewer plug. Then start the engine, set the idle at 1000rpms & shoot the light into the timing hole. Move the timing plate so that the 20° advance timing mark shows up in the center of the timing hole.
  
-**Moving the Cam Sensor Plate Clockwise (CW) will increase the Advance Before TDC. Moving the plate Counterclockwise (CCW) will retard (or reduce) the Advance Before TDC. Note that each timing mark on the plate (long-to-short) is equal to changing the ignition timing by 5°. Move the plate __VERY LITTLE__ to make adjustments.**+{{:​techtalk:​evo:​engctl:​camsensorplate.jpg?​400|}} 
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 +**Moving the Cam Sensor Plate Clockwise (CW) will increase the Advance Before TDC. Moving the plate Counterclockwise (CCW) will retard (or reduce) the Advance Before TDC. Note that each timing mark on the plate (long-to-short) is equal to changing the ignition timing by 5°. Move the plate __VERY LITTLE__ to make adjustments.** ​((aswracing post#17 at http://​xlforum.net/​forums/​showthread.php?​t=488663))
  
 The Cam Sensor Plate can be rotated slightly to accomodate getting the timing mark in the center of the timing hole. You can also move the plate to change the base timing (thus moving the whole curve sets up or down in rpm range) by setting the 1000rpm timing to a few degrees more or less than the specified (20° BTDC) advance timing mark. The Cam Sensor Plate can be rotated slightly to accomodate getting the timing mark in the center of the timing hole. You can also move the plate to change the base timing (thus moving the whole curve sets up or down in rpm range) by setting the 1000rpm timing to a few degrees more or less than the specified (20° BTDC) advance timing mark.