1973 4hp Evinrude

[film495]

I got some feedback on another forum vintage section, the white spots on the electrode are likely detonation or preignition. They are egging me on to install a knock sensor, but I'm not sure I'm that advanced mechanically, so - maybe I'll just use this as an excuse to pick up a timing light.

I got some colder plugs, I run B8S NGK in another one, and those plugs that have run for a couple years now, look happy and a nice brown, no fouling, both plugs look exactly the same, put them back in. Usually, that motor just gets pinned open, and we just ride around the islands, up and down the lake, nothing like a little boat, for the sake of a boat ride.

I could run more oil, or mess with what octane the fuel is, but I'll likely stick to 24:1 if I'm testing motors and regular 87 Octane pump fuel.

This motor was over heating before and I got the water pump going good, so - apparently the water pump was likely working perfectly good already and the overheating is from another reason.

 

[racerone]

I do not believe a " knock sensor " can be fitted on a 1973 4 HP !!!-----Who are these clowns suggesting that ?

 

[film495]

thanks for reading or commenting, this motor was a project so far for sure. I just want to practice working on one, and this one has been good for that.

can anyone recommend a timing light that works on these well? can you rig a battery and bulb to these? for static timing, can I just put a battery and bulb in a circuit, positive to the spark plug lead and then ground to frame? will the points opening and closing dim and bright the bulb? seems like something I could experiment with when I have a flywheel off to get at all the leads and see if I have to remove the ground from the coil, so - it tries to ground through the points.

you know, I gotta admit - I really like gaining more and more of an understanding of how these points ignitions work. 15 years or so ago, I paid a mechanic to do an ignition on the old 68 3hp Evinrude, and I was like - uuhhh, what's a points? I did an old Ariens S-12 with a single cylinder Kohler 12hp motor, first points. Just one point... lol

Do they make a small engine outboard that is a single cylinder or are they all twins and up? I'm just cracking up at the idea of idling down a single cylinder thumper on the back of a small rowboat.

 

[racerone]

There are numerous videos on how to set the points ( timing ) using the timing marks and an ohmmeter.----There is a timing tool that can be used.----A factory / shop time saver.----But you can use the timing marks on the flywheel and magneto plate as well.-----Learn about the timing on these simple magnetos.-----You will be glad you did.----Will take away all the guess work process that so many folks use.

 

[film495]

I do not believe a " knock sensor " can be fitted on a 1973 4 HP !!!-----Who are these clowns suggesting that ?

just some clowns on another part of the internet. they did jump right on a knock sensor, but just trying a timing light, and maybe running colder plugs, or a bit more oil in the gas, they went right to engineering a knock sensor on the fly. I'll let someone else try that if it ever happens.

They did pick out the white bits on the plugs as a problem, so - grabbing a timing light and giving it a look, seems like my path. I did pull apart a 70s twin Rotax 440 that had experienced detonation or pre ignition and it really just ate the inside of the head and it was like a marbled pitted mess.

I don't have high hopes for this motor, but hey - if I get it working and I have a couple others, you know - I might just give it to a friend of mine who's maybe been a bit down on his luck, if it ends up being a decent little runner, seems like that would be the right thing to do with it.

 

[film495]

I did check the timing with an ohm meter. It was opening just on the slow side, of the two marks. Right on the 2nd mark, but it supposed to be in the middle. My guess points a bit worn, either I'll replace them or just gap them a bit wider to adjust the timing. Motor seemed to run pretty good, last test in a bucket, not great, doesn't seem to want to idle down that well. Plugs looked more normal.

 

[film495]

Haven't had this motor back out to test. I need to pull the flywheel off another motor, and I'll probably do this one, and either put new points or open them up a hair more to .022 to see if I can get the timing to hit right in the middle. It was funny, one side had a hole in the bottom of the stator plate where the condenser screw goes, and the other side did not have that hole, not sure if someone did that or if that is how it came from the factory.

anyway, tinkering with how to use the ohm meter to check the static timing, seemed to figure out out quickly enough. I've done that on other motors with a battery and a light bulb, but the meter seems to indicate an open or closed connection well enough after fidgeting with it for a bit and getting the connections set up correctly.

 

[Crosbyman]

points gap is not to important what is important if points opening at the right instant