1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 69Get this manual
On 155 modelsloosen upper and lower carburetor lever adjusting screws which allows the return springs on the throttle shafts to fully close the throttle valves 4Partially rotate the throttle shaft open and then allow it to quickly snap to the closed position to be certain the throttle valve is closed in the throttle borePress lightly on tab of the adjusting link to remove backlashTighten the adjusting screwMove the throttle cam roller and check that all throttle valves start to rotate at the same time
Synchronization of the Throttle Cam with Spark Advance
100 Model
1Connect throttle shaft amplifiersuch as the one shown, to the throttle shaft2While rotating the throttle cam, the first embossed mark on the cam that contacts the cam roller should align with the center of the cam roller as tip of the amplifier begins to move
3To adjust, align the embossed mark on the throttle cam with
center of the cam roller, loosen the carburetor cam roller screwAllow the throttle spring to close the throttle valvesWhile pressing on the cam follower lever hold the cam roller against mark on the throttle cam and tighten the screwRecheck that the throttle valves begin to rotate as the embossed mark aligns with center of the cam roller