Honda BF35A-BF45A Outboard Motors Shop Manual., Page 313Get this manual
7Pinch the SE tubes using commercially available tube
clips keeping away from tube protector as shown8) Check the intake manifold vacuum difference between cylindersTake maximum vacuum difference between each cylinderIt should be 20 mmHg (0.75 inHg) or less9) If the vacuum difference between the cylinders is not 20 mmHg (0.75 inHg) or less, adjust as follows
[I] SE TUBE
[3] TUBE CLIP (2)
(Commercially available)
Adjustment:
The No3 carburetor is the synchronization base carburetorThis carburetor will not have synchronization adjusting screwAdjust the carburetor to get the least amount of vacuum difference between the cylindersAs the manifold vacuum difference decreases, the idle speed will become more stableTurn the No1 and No2 adjusting screws so that the vacuum difference between each cylinder is 20 mmHg (0.75 inHg) or lessAfter adjustment, check the idle speed and adjust if necessary by turning the No3 carburetor throttle stop screwSnap the throttle several times and allow the engine to return to idleCheck to be sure that the vacuum difference between each cylinder stays within 20 mmHg (0.75 inHg) or lessReadjust if necessaryStop the engine, remove the vacuum gauge, adapters and tube clipsInstall the 10 mm plugs and sealing washers