SUNBEAM S7 and S8 TWINS
  • SUNBEAM MOTORCYCLES. HEADER PAGE.
  • SUNBEAM NEWS and START PAGE
  • About the bike.
  • Distributor Internals
  • Redundant spark ignition.
  • Coil Information.
  • Beam-Spark Ignition Unit
  • FOR SALE
  • Smiths Chronometric Speedometer
  • Calibrating Smiths Chronometric Speedometer.
  • Speedometer Drives.
  • Companies and Products.
  • My other bikes.
  • The Horn. and Rear Brake Spring.
  • HOW TO PAGE
  • Modifications Page One
  • Modifications Page Two
  • Modifications Page Three
  • Dipsticks,sumps and oil weirs.
  • The Electrics
  • Sunbeam Dynamo in depth.
  • Repairs and Maintenance.
  • Carburettors
  • S8 Front forks.
  • Full width front brake on the S8.
  • Top dead centre.
  • Your Sunbeam.
  • All things wheels.
  • Data Sheets.
  • Engine breathing and oil leaks.
  • Putting the engine together.
  • Stainless Steel Exhaust
  • Tools
  • All things final drive
  • I80 Degree Crankshaft
  • Completed engine speed ignition sytem.

Redundant spark ignition. Plus further notes and pictures of the distributor cap and its fitting.



The 360 crankshaft employed in the Sunbeam engine lends itself to redundant spark ignition. Both pistons rise and fall together, this gives equal firing pulses. So if your distributor cap or rotor arm is on it's last legs, redundant spark ignition is the way to go. The distributor points becomes a switch only for the ignition system. A double ended coil is required to fire both plugs simultaneously. A Honda coil is shown below.

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Distributor with blanking cap. Please note the distributor cap has a clearance eccentric machined in it. As shown below. This is to provide good clearance for points spring steel mechanism.

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The two pictures above show a cutaway of the distributor cap showing points spring clearance and the white wire connection.

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Coil mounted underneath seat.

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Distributor with blanking cap fitted.

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Points only, no condenser or rotor arm. Points plate rotated 180 degrees so that ignition points are at top away from any oil. Points gap set to 6 thou.

Below is shown the plastic tophat, 4BA nut and washers.The retaining loop is also shown along with sample white wire showing 5 mm ringtag.

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Shown above is the supplied white wire and ringtag fitted under the tophat .

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Shown above is the white wire installed with the small  wire retainer installed ( This is supplied. )
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Carefully slide cap onto distributor body fitting the white wire into the machined slot, as shown above.
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 After fitting the cap line up the 4mm tapped hole with the hole vacated by the condenser. Now fit the supplied 4 mm cap screw and washer.
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Always make sure O ring is installed. Notice oil drain hole, lower centre of picture.
If the spindle oil seal fails this will prevent build up of oil in distributor

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