How to Set Outboard Ignition with a Timing Light

In this video we look at how to set timing on an outboard motor using a timing light. We'll look at using timing marks, top dead center and the light to get good ignition timing at idle.

Dangar Marine

About Dangar Marine

MarineEngine.com proudly sponsors the Dangar Marine YouTube Channel. Our friend Dangar Stu draws on his experience as a commercial boat skipper and mechanic to make some great how-to videos. Dangar Marine videos cover a range of relevant topics in outboard repair, boat repair/upgrades and seamanship. Subscribe on YouTube to be notified when new videos are released.

How to Set Outboard Ignition with a Timing Light – Video Transcript

Hey there, Dangar Stu here. Today's video is on adjusting the ignition timing on an outboard motor and is proudly sponsored by MarineEngine.com. Before we get going I just got to say it kind of made my day seeing all the funny comments you guys left on the clock video. I know I was a bit tongue-in-cheek but it's great to see a lot of people took it in the spirit it was intended you know, well, not a hundred percent but you know, most. The original video I did on setting the ignition timing on that Tohatsu motor, it covered a lot of the theory of ignition timing so I'm not going to go through that again. If you're interested in understanding what ignition timing is about then I recommend checking that video out because it goes through the theory for you. What was different about that video is the specifications for the timing we're all done on lengths of linkages so it was very much just in the spinners measuring things getting to the right specs. In this case we're going to be using a timing light which is another very common way of setting the timing.

The great thing about the timing light is that it shows you exactly what is actually happening. If for example in that situation with a Tohatsu I'd settle the linkages correctly and it wasn't running well it may be that Woodruff key that holds the flywheel onto the crankshaft had broken and sheared. I've got another video on that as well. If that shears it doesn't matter what you do with your linkages if that flywheels rotated on the crankshaft your timings going to be out. So that's another thing you can check. In this case though I'm going to throw the timing light on, we'll see what it is as idle. You need to be on the water really to be running at full throttle under load to see what your total or your advance timing is when you're running at speed. But we'll just get the idle timing right and hopefully get rid of that backfire. So, I'll show you quickly here the specification for this motor so you can see what we're aiming for adjusting it to. Here at the top we've got the ignition timing so we've got a fully retarded timing which is essentially your idle timing, which is seven degrees after top dead center, plus or minus one degree and that we're looking at full throttle at full advanced having twenty-five degrees before top dead center plus or minus one degree. There are basically three leads that come off a timing light like this. Positive and negative need to go to a battery to power it up.

The other lead is this one that clamps around the HT lead for cylinder number one. It's a little induction coil that has a current induced in it when the spark plug fires. Cylinder number one's always the top cylinder on all outboards. You'll also notice on here there's a little arrow sign towards the plug. So, when it goes on the lead it needs to go on so that arrows pointing towards the spark plug not back towards the ignition coil. In this case with the arrow pointing this way it just means it has to go on this way so the arrow is pointing towards this plug. Not go on that way so the arrow is pointing back towards the coil. Because this is a pull start motor it doesn't have a battery in it so I'm just going to hook it up to a separate battery. So just negatives to negative and positive to positive, as always. Now what I'll do is we'll just turn the water on, fire the motor up and have a look what the idle timing is set to now. Hopefully you could see then it was sitting at a few degrees before top dead center. So, the timing is actually a little bit too advanced, it's firing too early.

The way a timing light works is that every time a little bit of current gets induced in this coil, when spark plug number one fires, it flashes a light on and that gives you a kind of a strobe effect. So, what you're seeing is instead of a blurred spinning flywheel you're just seeing a little fraction of a second snapshot of the flywheel just when the sparks firing. So, your brain sort of sees a still image instead of a rotating image, of that point in time and then that part of the flywheel that's passing that needle will tell you exactly at what point in the cycle the sparks firing. So, in this case it's firing a few degrees before the piston reaches the very top of its travel. What we now need to do is wind that back so that the timing is more retarded, it happens later. So, we actually want the spark to happen seven degrees after top dead center. What I'll do now is show you how we adjust it. I won't be able to hold the timing light, the camera, and adjust all at the same time. So, I'll show you how he's adjusted then I'll just set the camera back on the stand and I'll slowly adjust it until it gets to seven degrees after.

Down here there's a little stopper screw and what that does is it pushes against the bottom of this lever. The more we push down the bottom of the lever the more the top the lever pushes to the right because that bolt is pushing it to the left and then vice-versa. What we need to do now is wind that bolt outwards so that the lever is able to move to the left and have the stator plate underneath the flywheel rotate clockwise, which is the same direction as the flow was turning and that will retard the timing. The way the ignition system works is there's a stator underneath the flywheel and that stator can rotate around the crankshaft. As the flywheel spins a magnet in the flywheel passes a coil on the stator, which induces a current in the coil and that then triggers the cd-i near its final spark plugs. Now if the flywheel's turning clockwise and then you rotate the stator clockwise, it will fire later in the cycle because it's got further to catch up to it. If you rotate that stator anti-clockwise and the flywheel was going clockwise you're sort of hitting into the motion of it and it will fire earlier in the cycle.

So, we now need to move it clockwise, so we're going to make the spark fire later, so instead of firing a couple of degrees before top dead center we wanted to fire seven degrees after top dead center. So, I'll fire it up again and then I'll put the timing light on it and then adjust that screw until we get seven degrees. What you'll also notice is as I adjust the timing, as you advance the timing, the idle speed will increase and as you retard the timing the idle speed will decrease. So, once you've got your timing correct to the spec you may need to adjust your idle to get that into range as well. As I back the screw off it got to about the top dead center and then it stopped moving and I'll show you why that is. What happens is, as this lever tries to go this way, the top can come this way because I've backed that bolt off but the leader here actually hits against the plunger for this dashpot that stops it going any further. The dashpots mounted onto a bracket and the bracket has these slots in it. So, if I loosen these two ten more fasteners, I can move this bracket further to the left, which allow this lever to come further into the retarded position. So, I'll back these off and move this across a little bit.

All right fired it up again. Let's see where we're at now. As you could hopefully see then, it does depend a bit on the framerate cameras I'm hoping it shows up on film alright. But we were sitting in about 4 or 5 degrees after top dead center. Which means we've got another couple of degrees to go. So, what I'm going to do now is lengthen that linkage from the top of the lever to the stator, I'll show you that. This linkage here connects this lever to the stator. So, if I lengthen this linkage I'm going to push the stator further clockwise and further retard it. So, I'm going to take this off, wind it out maybe three threads or something, put it back on, fire it up, put the light and see where we're at. I may need to adjust this a few times to get it right. I'm just going to pop it off from this end. Then I'm going to wind it out - so one, two, three turns then it's got this little locking nut in the back. I won't worry too much about tightening that up until we're done. So, pop it back up and put the light on again. As you can see then it was around a bit over six degrees after top dead center, so within that seven plus or minus one degree range. Still backfiring and popping a bit so I've got a feeling that's probably more lean condition causing that.

But at least we know now that our ignition timing for the idle timing is correct. I'm going to wrap this video up here because I want to try and keep these videos a little bit more to the themed rather than being these long rambling investigations. So, I think in this case we'll consider it a video on how to use a timing light and how to check your idle timing on the outboard. So hopefully this gives you an idea how that works. There pretty simple, three leads, point at the flywheel, find the marker, you're good to go! There's a few finer points that needle that the markers on is adjustable. So, it needs to be calibrated. So, the outboard truly is at top dead center the pistons up top dead center you know, in the position that that needles at. Most outboards I found are pretty much just set up right from the factory, so it's not something to really worry about. But if someone has played with it then be aware of it. Now we know the timings right I'm going to look into other reasons why that outboard might be sort of popping and sneezing and backfiring a bit like that. Classic reason is that its running lean. So, we'll be looking at all the reasons for that. So, we can look things like a vacuum leak, carbs being dirty, mixture screws, reed valves, all those kinds of things. So, we'll do that in a separate video next. All right well thanks as always for watching we'll pick this one up next week and see if you can figure out what's going on with it alright See you!