1901-1953 Indian Motorcycle – Parts – Accessories

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  5. Service Bulletin 3-8 Norton Motors, ltd., Headlamp, Front Fork, Magneto Chain – Twin Engine, Uneven Running – Twin Engine

Service Bulletin 3-8 Norton Motors, ltd., Headlamp, Front Fork, Magneto Chain – Twin Engine, Uneven Running – Twin Engine


The following information has been supplied by Norton Motors, Ltd.


A few instances of lighting failures have occurred due to insufficient grounding of the headlamp brackets to the rest of the the machine. The rμbber washer at the upper end of the fork top cover which carries the headlamp bracket prevents the proper grounding of the cover against the fork upper bracket, and the enamel between the upper and lower covers also acts as insulation at this joint. To insure proper grounding of the headlamp, a wire should be ran from the headlamp mounting screw to one of the speedometer mounting nuts. Future machines will be equipped in this manner.


For some time, we have recommended the use of only 1/4 pint of SAE 20 oil in each leg of the “Roadholder” fork instead of the original 1/2 pint specified. This reduction in oil will assist greatly in reducing fork leaks without in any
way affecting the action of the fork.


The three studs which hold the magneto to the crankcase are reduced in diameter at the magneto flange and allow movement of the magneto when the nuts are loosened. To adjust the magneto chain, remove the right hand foot rest and push the foot rest rod through towards the opposite side of the machine until the end is flush with the engine mounting plate. Remove the oil pipe junction block from the crankcase and plug the hole to prevent loss of oil. The nuts may now be loosened and the magneto moved to adjust the chain until there is 3/16 of an inch up and down motion. NOTE: Do not tighten the chain beyond this point, as there will be a tendency to make the automatic ignition advance mechanism bind and interfere with the timing.


It is sometimes difficult to obtain absolutely even running on a vertical twin engine, especially when both cylinders are supplied from a single carburetor. When all other attempts to smooth up the engine have failed, it is possible that reversing the intake manifold may be found helpful. There may be a certain amount of induction bias on one port which can be increased or nullified by the manifold. When installing the carburetor or intake manifold, the gaskets must be placed an the studs and checked carefully to be sure that they do not overlap the manifold or cylinder head bores.

Stuart E. Watson
Service Manager

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