Re: 1975 johnson 9.9 spits and sputters but won't start
Timing is set by the points. You will need to remove the flywheel to set them correctly. To do that you will need a balanced harmonic puller and a big strap wrench to hold the flywheel in position when you remove and torque back down the flywheel nut.
Once the flywheel is removed, turn the center cam (with motor in gear you can turn that by turning the propeller) until a point's rub bar is on the SET position. Set the points gap to 0.020" for both points. There is a slot screw that is loosened and a notch on the outer end of the point to push on to change the gap. When the gap is set, tighten down the slot screw. When they are set correctly, take a clean white business card and dip it in lacquer thinner and pull it through each point and immediately blow them with compressed air. You cannot have any dirt or oils on them. Add a drop or two (no more) of motor oil on the cam wick and you are done. I think the flywheel is torqued back down at 45 ft/lbs but check your spec. to be sure.
The other timing issue is the carb's link and sync which sets your timing advance. You might want to check this first in case it is really out of alignment. It could be your problem. When you turn the throttle grip you will notice the throttle cam that comes around and pushes on the carburetors throttle roller. When that roller JUST touches the cam, the little arrow on that cam must be in the middle of the roller. If it is not, there are two 5/16" hex nuts on the starboard side, just under the flywheel that can be loosened to adjust the throttle cam. To loosen the nuts you will either need the flywheel off or a very thin 5/16" wrench.
Lastly, your start up procedure. On my 1975 9.9HP I completely ignore the info on the throttle grip, like where to set it when you start. The starting position for that motor is full on against the neutral stop. Anything less and you can pull till the cows come home, at times.
