Make and Make Do  

By Rob Rohde-Szudy - Madison, Wisconsin - USA


Outboard Motor Dirty Tricks

This installment is a collection of useful tricks for outboard
motors that are each too small to warrant an entire column.

Another Kind of Kill Switch

We’ve all read about how a kill switch is vitally important when running a motor. If you fall overboard you don’t want the boat continuing on its merry way to run down you or someone else. It’s easy to wire a kill switch, and Max Wawrzyniak covers how to add the wiring to “unwired” outboards in his book, Cheap Outboards. You can find the same information online too, if you look around, but the book has it in its most complete form.

I’m not afraid of doing the wiring, but I wanted the safety feature to be in place until I got around to pulling the flywheel for the next ignition rebuild. You’re in luck if you have it set up for remote controls. So here’s my quickie safety lanyard.

I tie a line to the throttle stick

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And run it through a hole in the thwart. This would be better if it were a screweye level with the top of the control box.

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And the other end of the line is tied to a pinch clamp that connects to my belt loop.

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The idea is that the clip holds on strongly enough to close the throttle, but that if it doesn’t and you fall overboard, it will pop off the belt loop before it drags you. I am not sure how completely reliable this is, so I don’t treat it as an ironclad backup. Actually, I think nobody should treat any of these things that way, because it it easy to forget to clip a lanyard back on after going forward, for example. I only bother wearing this when I’m out solo, since I’m pretty sure my wife could grab the tiller. In a planing boat I’d always wear it, but I would probably also make a higher priority of installing the real thing.

Oil Ratio Measure

Measuring the correct amount of oil is always a pain unless you have a dedicated measuring vessel. They make jars with gradations on the side, but they’re for large motors and accordingly are way bigger than we need. So I made one. I think any plastic jar would do. This one happened to be from an engine oil test kit, so it has another jar it fits inside. This is convenient because it contains the mess if I make one. Setting it up is easy. Divide 128 (ounces per gallon) by your fuel to oil ratio. Make your life easier by multiplying this by 29.57 so you can measure it in milliliters. Then you can use a metric syringe available at any agricultural supply store or veterinary office. (Tell them you don’t need the needle if they’re worried. And get a few because these are really handy!) Measure water into the jar and mark the amount of oil needed for ¼ gallon, ½, ¾ and a full gallon. More if your jar is big enough. But beware, because ethanol erases most permanent markers! I covered mine with packing tape, but I’m not sure how perfect that solution is. Time will tell.

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After I made this, I found an oil measuring syringe at Farm & Fleet. This might be an improvement on the jar method, since you can suck up some gas to rinse out the oil. But I still think you need a jar to store it in to contain the oily mess and keep dirt from finding its way into your fuel.

Homemade gas can adapter

In most cases the purpose-made gas tanks are the best way to go. But many times sailboats don’t really have a good place to put one. Outboard gas tanks under 6 gallons are rather exotic where I live. The simplest solution is to use one of the readily available 2-gallon gas cans. But it needs an outboard connector.

They make a system like this called “Adapt-a-Can” in Canada. It costs $30 and might be worth it if you’re in a hurry and don’t have parts already laying around. But you know me – I have tons of junk laying around. So I found a brass fitting that had ¼” hose barb at one end and ¼” female pipe thread at the other end. This fits an OMC fuel tank connector. It also fits through a ½” hole drilled in the disk that seals a standard 2 gallon plastic gas can.

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Well, it almost fits. It took a little belt-sanding to expose enough thread.

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Then it goes together with some Teflon tape. Be sure it’s the yellow stuff that’s rated for petroleum. The white stuff only handles water.

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I added a foot of fuel line and an inline pickup filter to make something very much like the Adapt-A-Can system.

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That’s about $15 in parts. So it might be worth the $15 difference to simply buy one depending on what you have for parts and time. Nonetheless, it’s good to know about this if your fuel tank ever quits on you in the middle of nowhere.

Actually, the most useful feature of this is far simpler. You never need to pour gas from one tank to another underway. Just move the adapter to the next tank.

Spill-Free Refueling

Speaking of gas can mods, this is not my idea at all, but it so good I have to draw attention to it. Take note if you have a motor with a built-in tank. I found THIS on the Shallow Water Sailor site. The trouble is that it is terribly easy to spill fuel when refilling a small tank underway. Walt Elliot figured out how to fix this by adding a valve and tubes to the gas can.

You put the tubes in the tank and the hose clamp sets them at the right height inside the tank. Lift the gas can and open the valve and the fuel will run into the tank until it blocks the vent tube. That shuts off the fuel flow! No vent air means no fuel. Close the valve, lift the hoses, let the drip a bit, and put all the caps on. See the link above for a diagram and construction details.

One limitation should be noted, however. The cheap plastic gas cans I use are too flexible for this. Even if you close the vent, fuel will continue to flow and partly collapse the can. This only works well with a rigid gas can. Without a rigid gas can, the best way might be to pump fuel into the motor’s tank with a small hand pump. Harbor Freight sells them for like $5, but you’ll want to glue the connections to prevent leakage. Or you could use a primer bulb as a pump (and develop really strong hands).

Remote Controls for Motors Without Locks

This might not be the most common request, but I found I needed remote steering on an old 5.5 hp Johnson. Remote steering on a small motor is handy on a sailboat, and I could also see a powerboater wanting to remote control both the big motor and the kicker. But little motors generally don’t have the cable locks, even though OMC is kind enough to provide all the other fittings. Fortunately, adding the lock is easy.

Actually my old 1954 didn’t have the throttle fitting either, but it was cheaply and easily swapped from a later model. Likewise the holes for the throttle lock were there, needing only the lock itself. The shift lever also had all that was needed. The trouble was the shift lock. OMC never imagined anyone would want to remote control a small engine, so the cowling wasn’t made with the requisite standoff.

I got this one wrong the first time around. I assumed that measuring the position of the lock on another motor would work, but I didn’t account for the fact that this other motor had a much bigger cowling than mine. Here’s what my first attempt looked like. I cast it in JB Weld my making a little coffer dam of paper and tape.

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It sure looks nice, but it’s too close to the shift lever! With actual cable in hand I learned that the lock has to be forward of the control panel on these little motors. So I bent a piece of scrap aluminum and screwed it on.

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Here it is with the cable in place.

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I keep telling myself I’m going to start measuring twice…

Quick & Dirty Shift Cable End

Speaking of remote controls, control cables have a sleeve actuator at the ends. The cable is fastened to a sleeve that slides back and forth on the outside of the rigid brass tube at the end of the cable. That outer sleeve is plastic, and breaks if you step on it. You guessed it – I found that out the hard way. (Don’t be a dummy like me – hang your cables up out of the way until you install them!) These are common parts and very cheap from your local AOMCI guru, but my local contact didn’t have any. It was going to be a couple weeks before he visited the regional AOMCI grand poobah up north. And I didn’t want to wait!

Fortunately, the fix was pretty simple. The cable end is ¼” tubing, so I just needed something that could fit over that. I happened to have some scrap ½” brass rod and a couple of hours free.

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The first step was to center punch both ends of the rod. This can be done by eye, but look at it from two places 90 degrees from one another.

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Then I bored the rod lengthwise to the same depth as the old plastic sleeve fitting. Again, look at it from two positions. Remember to use a sharp bit with oil, and retract frequently to remove shavings. I bored with a smallish bit, then enlarged to 5/16”. I think it’s easier to control that way. Remember to measure the depth of the original hole and mark your bit with some tape.

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From the other end I then drilled a hole just big enough to accommodate the center wire of the cable. Then, again matching to the original piece, I center punched the two side holes. The hole for the locking pin is ¼” The other one is smaller, since it needs to be tapped to 8-32 tread. After drilling and tapping, the locking pin is fitted by driving out the cross pin, inserting in its new hole, then hammering the cross pin back in. The cable is set-screwed into place just like normal. This is what it looks like.

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There we have a working shift cable end. If you had to buy everything it would probably cost more than getting one through AOMCI, but it works if you’re in a hurry. And it’s free if you have scrap laying around.

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Crankcase Test Jig

One of the most difficult two-stroke engine problems to diagnose is poor crankcase compression/vacuum. After I did the fuel pump conversion on the Johnson 5.5. (For instructions, see Max’s book.) It ran fine for a while, then stopped running. No pulsations to the fuel pump. I took off the carb and manifold to discover that my gasket sealant was gone! Maybe I started running fuel through it before it was fully cured. Or maybe my ethanol fuel ate the sealant.

While I was at it I decided to check crankcase compression to make sure there wasn’t a bigger problem. By pressing the palm of my hand over each crankcase’s intake and turning the flywheel I should feel something. As I turned the flywheel (spark plugs removed), the lower crankcase predictably “burped” a little air past my hand, even though I couldn’t feel the vacuum at all. The upper crankcase didn’t. I was pretty sure the upper crankcase seal was shot, but I decided I needed a better way to measure this. The “palm burp” is hardly foolproof.

I cut a scrap of 1/4” aluminum plate about the size of the gasket. Steel would work too, but it’s harder to work. Using the gasket, I center-punched the positions of the holes and bored them. I also bored and tapped holes for a hose barb for each port. Once bored, I lapped the plate to form a completely flat gasket mating surface. Just like sharpening edge tools, this was done on emery cloth laid on a flat piece of glass. (Actually I have a marble tile for this.)

Don’t be afraid of lapping – it’s easy, even though it can take a while. Apply even pressure and scrub the metal on the coarse abrasive until it is evenly covered with scratches. Go to finer grit and scrub until the scratches from the previous grit are removed. This doesn’t take long. But rotate the metal 90 degrees whenever you change grit or it will be very hard to tell when you’re done. Get four or five sheets of coarse emery, then one each of medium, fine and crocus cloth. Any real hardware store should have these abrasives for under $2 per sheet. Here’s the lapping setup.

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After lapping, I simply screwed in two hose barbs with Teflon tape. I used the yellow stuff for the reasons mentioned above.

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Then it is a simple matter to screw it on and use a cheap automotive vacuum/pressure gauge. These are $10-15 new, but I got this one for $2 at a yard sale. It doesn’t zero accurately, but I only need a relative reading. You might need shorter screws than the actual manifold uses, or some stacks of washers. I used some oversized nuts under the screw heads. Don’t force any screws too deep or you might ruin the casting, and definitely don’t over-torque or you’ll strip the threads. Here it is in situ.

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Notice that the test plate is shaped to leave the crankcase bleeder valves in place. This is important, because these valves could be the cause of poor crankcase vacuum if they are leaking.

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I’m really glad I built this before beginning the (reportedly difficult) process of replacing the upper seal. Both crankcases showed similar vacuum and pressure pulses. I’m not sure why my hand could seal better over the lower port, but it is reassuring to know I can test it accurately whenever I need to.

Making Your Own Gaskets

Speaking of the intake manifold, there are two gaskets – manifold to reed plate and reed plate to crankcase. These gaskets are not always available for older engines. But they are easy to make. Fiber gasket material is available quite cheaply at any auto parts store or real hardware store.

First store the material overnight flattened between two books. This keeps it from constantly trying to roll up. Trace the old gasket onto the material in pencil. Then carefully cut along the lines with a razor blade. The smaller holes are best punched out with leather punches. If necessary you can make such punches by sharpening the edges of a piece of small tubing.

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If your old gasket didn’t come off in tact things are not so easy. Then you need to do a crayon rubbing of the mating surfaces and draw on the openings based on the remnants of the gasket. Paste the rubbing on cardstock and cut to the lines. This will then serve as a template for future gaskets. Assuming you didn’t miss one of those little oil holes and cook your engine. Be certain you get all those holes! You can see why it pays to take the time and care to get the old gasket off in one piece.

So there you have a few more ways of making the old outboard a little easier to live with.

Rob Rohde-Szudy
Madison, Wisconsin, USA

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