Force 120 Hard Start

[Jiggz]

Re: Force 120 Hard Start

JP, in the synch and link prepared by Frank, he zero'ed the cam with the eccentric screw by disconnecting the timing tower from the throttle linkage which in essence also zero the idle. You can achieve the same by just backing out the idle screw without having to disconnect the timing tower from the throttle linkages. And with the idle screw set at zero, the scribes on the cam should align with the eccentric screw slot, if not then you will need to adjust the linkages between the timing tower and the throttle linkage. From here you can set your timing, but thereafter you will need to set you idle.

With idle set a zero (after setting the timing), it is very hard to set the idle since the engine dies due to lack of idle setting. So what you will need to do is to give it initial setting by turning the idle screw CW until the cam is slightly pushing against the roller. The initial setting could be too high or too low but at least the engine is not shutting down on you. Adjust idle neutral RPM around 900 RPM in water or a little higher on muffs.

 

[jpwilly]

Re: Force 120 Hard Start

@Jiggz, that makes sense. I disconnected the linkage but wasn't aware that backing out the idle screw did the same thing. Thanks for clarification. My first outboard so I'm learning.

 

[MickLovin]

Re: Force 120 Hard Start

I really can't see how you know what your idling at and if your idle screw is set right considering you don't have a tacho, besides frank's tutorial, the book says you put it in forward and to the lowest idling speed, adjust/sync carbies etc,etc, then set the idle to between 700-800 in fwd. How can you set it when you don't have a tacho, sorry to go on and on but it may be your problem your idle isn't set right still.
But frank is the best man to ask, that's just my opinion.

 

[Frank Acampora]

Re: Force 120 Hard Start

For clarification: When synchronizing carbs, you MUST use the ball link to set wide open throttle. Position of the idle stop screw does not matter. Put it wherever you want. You will adjust it later.

Since there is a wide open throttle stop on the timing tower, if you use the idle stop screw to set the carbs fully closed, without adjusting the ball link,then, you may or may not get wide open throttle at full tower travel.

THUS: You first remove the ball link and set the throttle cam to just touch the roller with the mark(s) just tangent to it. THEN, you re-attach the ball link and adjust the cam so that at WOT, the carb butterflies are horizontal. Note that in all this adjustment, the idle stop screw does not come into play. Also note that when correctly adjusted and idle set with the stop screw, the marks on the cam most likely will not touch the roller but will be below it, opening the carbs a slight crack. (and advancing timing a degree or two)

NOW, The idle stop screw controls both timing and carb opening. So, ONCE the WOT timing has been set there is no way to actively change it such as by vacuum advance--it is set permanently.

Once carbs are set close to their correct idle mixture--1 to 1 1/4 turns out-- you use the idle stop screw to set the idle speed. As you adjust carb mixture, speed will increase or decrease and the idle stop screw is adjusted accordingly.

NOW: since the propeller is a direct load on the engine, if you change pitch, it will either load or unload the engine. THUS when changing props, especially pitch, engine idle speed will change and the idle stop screw must be adjusted to bring idle back into specs.