All Joe Hunt Points Type Magnetos Installation Instructions, British Twins
PARTS #1278, #1279, #1280, #1281
Remove spark plugs and gap .018. Remove cover (R.H. Side of engine) over battery ignition points. Disconnect and
tape (insulate) all battery connected wires.
Hold breaker cam in opposite direction of rotation (advanced position) and rotate engine until the points on #1
cylinder just start to open. NOTE: Use .0015 feeler gauge or Joe Hunt timing device.
Remove breaker plate, breaker cam advance mechanism, and dowel pin from internal taper if your model used a dowel
pin to position breaker cam and advance mechanism.
CAUTION: Do Not Rotate Engine. If engine is rotated, reverse rotation until piston is down and the cylinder at least
one inch before top center on the compression stroke.
Rotate engine in normal direction of rotation until piston is 5/16 from top center on compression stroke. Install
magnetos adaptor plate and adaptor shaft in cam taper. DO NOT TIGHTEN SHAFT.
CAUTION: 1963 to 1970 Triumph unit construction twins have a different length taper on shaft and internal threads
are dissimilar. We suggest checking threads and taper. 1963 to 1970 bolt has BSF 1/4 x 26 threads. 1971 and later
bolt had 1/4 x 28 thread. Early shafts are marked with the letter "A". Later shafts are marked with "B".
NOTE: Some applications will require drilling and tapping engine with 1/4 x 20 for better security. Some customers
with severe service report that they heli aced adaptor to cam cover with approximately one inch length bead, top and
bottom for security.
Remove Magneto cover. With shaft slightly loose in taper mount Magneto so that points are just starting to open and
bolts are approximately in center of slot (for timing adjustment later).
Carefully remove Magneto and tighten center bolt in shaft. Re-install Magneto and time. Install cover and plug wires.
Hook up ground wire to a separate kill switch to ground only.
DO NOT HOOK ANY BATTERY CURRENT TO MAGNETO.
Point Gap .012 to .015
Above instructions are for fitting RH mounted mags on unit Triumph and BSA twins. When fitting a Hunt mag to a
Norton Commando, use the timing marks in primary case as noted in service manual. When fitting a 334-1278 rear
mounted mag to a pre-unit twin to replace a Lucas K2F or a BTH magneto, installation and timing is exactly as noted in
your service manual, as the #1278 is a direct replacement for the original magneto.
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