How do you start a 1970 Eska 3.5 outboard motor?

Well, I have no idea how the motor looks. But here are the basics. Step1: Connect fuel sorce. Step2: Prime fuel sorce. Step3: Put the carburetor in the choked position, and throttle is in the idle position. Step4: If equipped with a gear selector make sure position is in neutral. Step5: Make sure kill switch is deactivated. Step6: Pull the pull rope. If it is not equipped with a pull rope, there should be notches in the flywheel located on top of the engine to which you should be able to wrap a length of rope around and then pull.

Adding to the above:

These usually had a position marked "start" on the throttle, use that instead of idle. On these engines, the speed control advances the ignition as well as opening the throttle butterfly valve, and the "start" marking gives throttle and advance settings that should result in easiest starting.

Once you get it to hit with the choke full on, put the choke to half and it should start.

There is a detent for half choke, but it may be hard to feel on an old dirty engine. Pop the cover and you will see how the lever on the choke plate has a spring that rides in 3 detents (off, half and full) you just need to be somewhere close for half choke, so take note of where that puts the control.

Once it is running at half choke, slowly move the choke to off over a few minutes as it warms up. Unless it is very cold (duck hunting?) I only do one pull with full choke to avoid flooding, this is nearly always enough to prime the engine enough to start on half choke.

If you take the choke off to fast, you may need to prime it again using 1 pull at full choke, but try starting it at half choke first so you don't flood it if it doesn't need the prime.

If it won't hit at all, then squirt a few drops of fuel/oil mixture in the carb inlet and see if it will fire then. If it will run for a few seconds this way, then you need to clean & rebuild the carb. If it won't investigate the ignition system starting with the plug and wire, then the points.

If your engine does not have a gearshift:

Be sure you are seated in the boat when you pull that rope. There is a chance that the boat can accelerate rapidly (well as much as a 3.5hp can be rapid) and toss you in the lake. Keep track of where the boat is turning/drifting while you are fussing with the motor, and be ready to steer the engine as required as soon as it starts to keep it out of rocks, traffic, etc. If the shore is steep enough, it may be best to start the motor with the bow pushed up to the shore or tied to a dock so the boat doesn't move before you are ready. You get reverse by turning the motor 180 degrees.