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Helping keep British Motorcycles on the road for over 30 years - established 1977

 

TESTING FOR COMMON CHARGING AND NO SPARK PROBLEMS ON BRITISH BIKES WITH ALTERNATORS AND BATTERY/COIL IGNITION, NON DISTRIBUTOR TYPE.

CHARGING PROBLEMS: TEST STATOR FOR CONTINUITY BETWEEN BOTH WIRES AFTER UNPLUGGING FROM RECTIFIER. YOU SHOULD  THEN CHECK FOR CONTINUITY TO ENGINE CASE. YOU SHOULD HAVE NONE. IF STATOR IS OK, CHECK ROTOR FOR LOOSENESS ON SHAFT AND IF OK, REMOVE FROM CRANK AND TEST MAGNETISM. A CRUDE TEST CAN BE MADE BY ATTEMPTING  TO PICK IT UP WITH A SCREWDRIVER FROM YOUR WOODEN WORKBENCH BY EACH OF THE SIX MAGNETIC POLES. A NEW STATOR TAKES APPROX. 16 POUNDS OF PULL ON EACH MAGNET TO PULL IT OFF OF A METAL SURFACE, AND CAN BE ACCURATELY BE CHECKED BY TYING A STRING THROUGH THE HOLE AND PULLING IT OFF THE TOP OF A BENCH VICE ANVIL WITH A FISHING SCALE, ON EACH OF THE SIX MAGNETS.  IF IT FAILS THIS TEST BY MUCH, OR IS LOOSE ON SHAFT, REPLACE. CHECK RECTIFIER FOR CONTINUITY ACROSS EVERY PAIR OF TERMINALS BACK & FORTH. YOU SHOULD ONLY GET CONTINUITY IN ONE DIRECTION!

SPARK PROBLEM: UNPLUG POINTS WIRES FROM COILS. TEST FOR CONTINUITY
FROM EACH POINTS WIRE TO GROUND WHILE KICKING OVER BIKE. IF IT DOES NOT MAKE AND BREAK CONNECTION TO GROUND, REMOVE NUT ON EACH SET OF POINTS HOLDING POINTS WIRE ON, AND REASSEMBLE AS FOLLOWS ON THREADED STUD FOR EACH SET OF POINTS: INSULATING WASHER, POINTS SPRING, POINTS WIRE, INSULATION WASHER, NUT.

TRY AGAIN. IF YOU THEN GET INTERMITTENT CONTINUITY AS YOU ROTATE
ENGINE, MAKE SURE THE POINTS FOR EACH CYLINDER ARE JUST OPENING AS THAT PISTON IS APPROACHING TOP DEAD CENTRE ON COMPRESSION STROKE. OF COURSE, BEFORE GOING RIDING, MAKE SURE POINTS GAP FOR EACH SET OF POINTS IS CORRECT WHEN THE ADVANCE CAM SCRIBE MARK IS LINED UP WITH THE POINTS "HEEL", THEN CLEAN EACH SET OF CONTACTS OFF WITH SURFACES INSIDE THE ADVANCE UNIT) SHOULD ALL BE CLEAN AND LUBED WITH DISTRIBUTOR GREASE.

CHECK WITH STROBE LIGHT AFTER YOU START BIKE TO MAKE SURE TIMING MARKS IN PRIMARY CASE LINE UP AT 3000 RPM AND MOVE BACK TO RETARDED POSITION WHEN ENGINE IDLES. IF YOU HAVE NO TIMING MARKS IN PRIMARY CASE, CONTACT US (OR BUY A COPY OF "MODERN MOTORCYCLE MECHANICS" ) TO GET THE DISTANCE BEFORE TOP DEAD CENTRE ON COMPRESSION STROKE THE PISTON  SHOULD BE LOCATED AT (MEASURED THRU THE SPARKPLUG HOLE) WHEN YOU TURN THE ADVANCE CAM AGAINST SPRING PRESSURE AND ADJUST THE TIMING ON EACH SET OF POINTS TO JUST BE BREAKING AT THE END OF THE TRAVEL OF THE ADVANCE CAM, BEFORE ROTATING THE ENGINE A FULL TURN ON A TWIN TO SET THE OTHER SET OF POINTS.

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