p/n TRI, Unit Construction Triumph Installation
Overview: The Morris Magneto TRI magneto is driven by the left side of the exhaust camshaft, and as such rotates in the opposite direction of the typical motorcycle magneto; points are the ‘left hand’ type (p/n P5L). Remove the tach drive unit with a thin-wall 7/16 socket; threads are usually left-handed, but may also be right-handed; mount bolt provided is left-hand, so you will need to contact Morris Magnetos if yours is right-handed. Next, you will need to see what type of drive slot is on the end of the cam. You may have a thick headed flat topped screw, a slot cut directly into the end of the cam, or a ‘thimble’. With the screw type, the drive shaft tang will fit with only slight play into the slot. With the cut slot type, you will need to determine if slot width is standard (approx. 0.100 inch); many non-stock cams are this style, so you will need to check. If shaft tang fits loosely, contact Morris Magneto for how to proceed. Thimble type is a stamped steel piece pressed into the cam end, and can be identified by the 2 ears on the outside of the stamping. The important thing is that the thimble is not loose; check by using a screwdriver in the slot, twisting and pulling. Morris Magnetos are designed to have the least magnetic pulsing, for very little drag when running, so it is important that no debris gets into the magneto when the cap is removed, particularly metal that the magnets will attract.
Turn the engine to where the advanced timing slot aligns in the timing hole, or per Triumph. Clean engine case threads carefully, install drive housing and mount bolt, using loctite on the threads and mating surface, for rigidity and sealing. Shift drive housing opposite the mount bolt when tightening, to help prevent loosening. You may wish to use a thin piece of aluminum, brass, or other rigid material to protect the engine case surface. Install the drive shaft, being careful not to damage the small seal. With slot fully seated, thread on the hex drive nut so it does not bottom out against the magneto; do so by setting it where it just hits, then back it off by turning one thread further. Flange on hex drive nut should be about flush with the top of the drive housing. Snug the jam nut temporarily. Remove the magneto cap, and turn the magneto to where the contact points have just opened slightly (cam turns counter-clockwise). Hex drive nut must align with the magneto socket when the magneto is slipped in, with the magneto housing shifted clockwise, to the back of the adjustment slots. If it does not, turn nut slightly so that it does. Remove drive shaft, mark the hex position, and tighten the jam nut securely. If necessary, use pliers to hold the shaft just below the threads. Position is correct when magneto has enough movement in slots to set advanced and retard timings.
Apply grease to magneto rotor socket, drive shaft ends, and magneto base plate. Install magneto with washers, lockwashers, and stopnuts. Tighten nuts until lockwashers begin to compress. Install timing adjustment screws and pieces of the small spring (cut as required), using blue loctite. Attach the large spring between rear (retarded) adjusting screw and front magneto mount stud. Set advanced timing (front adjusting screw) so points are just opening. Static timing is all that is required. If you wish, you can check for 'points open' by using a good digital ohmmeter; reading will increase by about .2 or .3 ohms. Re-install cap (make sure springs line up), and tighten so gasket does not compress more than 25%. Retard timing adjusting screw should be set so that end of magneto moves approximately 5/8" from advanced timing position. Retard timing is used for starting and can also be used for idling. When riding, magneto must be advanced, or you could overheat engine. With the proper mounting nuts tension, magneto will stay retarded for starting and idling. As the throttle is opened, vibration from the engine permits the spring to pull the magneto advanced automatically. Stud on side of magneto is used to "kill" magneto with a grounding toggle switch or lever (p/n KSL). Do not connect to your 12-volt system!
Stuff to know: The long-lasting OEM-type points in your magneto have been set at .015, and will require no attention for years. When replacement is necessary, use Morris p/n P5L and condensor p/n P6. Use only original type cap, gasket, points and condenser. Initial spark plug gap, .020 -.025". Due to the hot spark, the gap will burn larger somewhat faster than with a battery ignition. Use of a single-fire module, Morris p/n MSF, may help prolong plug life. Use non-resistor spark plugs and copper or stainless steel (non-suppression) plug wires (Morris p/n MWS). US Patents apply.