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Johnson Service Bulletin SB-1095 (1966) - Mis-use of Timing Fixtures
Issued June 3, 1966, this two-page factory bulletin explains how repeated use of an unsecured timing fixture can enlarge its keyway, compromising ignition timing and engine performance on Johnson two-cylinder outboards. The factory directs mechanics to secure the fixture with the flywheel nut and replace worn fixtures.
June 3, 1966
SUBJECT: MIS-USE OF TIMING FIXTURES
ON MODELS: ALL TWO CYLINDER ENGINES
The use of timing fixtures is recommended to synchronize the points and set the timing of our two cylinder engines because of the accuracy obtainable through their use. Thus, timing fixtures are a necessary and vital service tool in obtaining peak engine performance - if they are properly used and maintained.
It has been reported, however, that repeated mis-use of timing fixtures can result in very sick running engines. This holds true even if the fixture is properly used for timing and synchronization of subsequent engines. The reason for this seems to result from haste in the use of this tool. All too often, the timing fixture is placed loosely on the crankshaft without anything to hold it in place. This practice results in the fixture keyway becoming enlarged, after repeated use, and the
CHECK FOR ENLARGED KEYWAY AND
REPLACE FIXTURES IN QUESTION-
ABLE CONDITION.
JOHNSON MOTORS, DIVISION OF OUTBOARD MARINE CORPORATION, WAUKEGAN, ILLINOIS 60085
accuracy of any work done with it is questionable.
We recommend that whenever a timing fixture is used, the flywheel nut be screwed onto the crankshaft to the point where the nut just touches the timing fixture. If this is done, your work will be more accurate and the life of the timing fixture will be greatly extended.
N. Peter Hansen
Administrative Assistant
NPH:rm
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