Johnson

johnson_9.9_magneto.htm
Johnson, Evinrude, OMC, outboard motor, outboard motor repair, 9.9, 15 hp, date/year of manufacture, water pump, carburetor, long shaft, 15 hp conversion, sailmaster

	Maintaining Johnson/Evinrude 2 cycle outboards Magneto Ignition 1949 – 1976 +
1949 5 hp TD-20		1972 6hp Fisherman

This magneto system is pretty basic to most of the previous Johnson/Evinrude motors in various sizes. Magneto ignition was used on all the OMC motors up until about 1976. However some of the later smaller single cylinder motors (4hp) may still have magneto ignition for a number of years later. The earlier models will have coils mounted under the flywheel while some later motors use external coils.

Most of us now days are spoiled by CDI / electronic ignition on these post 9.9hp 1976 and post 1977 for the 6 and 8hp motors, even larger motors of that era. All else being OK, it was taken for granted that if you have spark, the motor will run fine, and that is correct ..... for electronic ignition.

This magneto ignition article can also be used/adapted for about all the other OMC magneto type ignition motors of any size.

But, for those who are new to the older engines having a magneto ignition, points are a different animal altogether, and even though you can get spark, and they may allow the engine to run, it may not be optimum unless the points are careful set and checked against the timing marks on the timing plate. Failure to do so can result in poor engine performance, a huge difference in smooth trolling idle and top end power with possible detonation under high loads, plus poor fuel economy. OK, you may luck out on the first try, but even a blind squirrel finds an acorn at times.

Therefore, it is critical to get points perfectly set on the mark. On twins, it is even more critical because it affects the balance of the power impulses which are traveling through all the moving parts, and can cause at a minimum, poor performance, moderate vibration, and if really out of synch, it can wear out and break things eventually.

So, spend the extra time up front, and be rewarded with many hours of trouble free operation. Points rarely fail, the weakest link is the newer condensers (Asian mfg) which are inferior to ones made before about 1985 (USA mfg.). Coils on these series are almost indestructible, and in that many experienced users have never been stranded by the magneto driven motors due to an ignition problem. 1977 and on OMC 9.9/15 engines cannot match that reputation because they do have a habit of occasionally blowing out the power pack module (for whatever reason) on the CDI ignition.

Many older knowledgeable boaters prefer the points system on a backup motor, especially when you're 15 miles plus offshore. BUT they do not just throw it in a corner and forget about it, they to take care of it and start it up from time to time.

The factory built a timing bracket for use by service centers for these motors that was simply a thin flat bar with a center tapered hub to match the crankshaft/key timing. This fitted in place of the flywheel and protruded out to the diameter to clear the timing plate, it had a downward pointer on the outer (2) ends that allowed you to adjust the points at the same time you could fine tune them to time the firing.

Now, I am assuming that you have some idea of how a outboard motor functions and understand how to remove and reinstall the flywheel.

Ignition 1949 thru 1973 : These series of motors used a magneto ignition system with points and condenser ignition which shared common parts with many of the other Johnson / Evinrude motors of the same era. The coils, especially those in the 60's motors have a reputation for cracking and allowing moisture in and then starting to break down, creating problems. They changed the plastic formulation on the coils at some stage and the replacement ones are fine. About 60% of the old motors I have seen have needed one or more coils replacing, and would be financially unviable for someone not working on their own motor.

A lot of people will replace the coils without replacing the spark plug leads. Even if they do, often times the connection from the coil to the spark plug lead is not very good. The faces of the coils also have to be lined up with the machined face perfectly or you're spark will not be perfect. Those who run the old spark plug leads after changing the coils will often overlook the spark plug boot connections too as these are usually hidden inside the rubber boot.

First it is recommended that you loosen the flywheel, then remove the spark plugs. This will allow you to rotate the flywheel/crankshaft easier when making the point settings.

How the magneto system works is, there will be a cam on the upward protruding crankshaft. This cam sits just above the timing plate and is located (timed) by being secured in place using the flywheel key. As the crankshaft is rotated, the thickest part of this cam pushes a wear strip of the movable points arm. This thick part is also usually the location of the flywheel key. Sometimes there may be a word SET, stamped in the thickest part of the cam, if not, then just rotate the shaft to where the highest part of the cam moves the points the most. That will be your setting location.

There are two screws holding each set of points to the timing plate. The inner screw should be loosened and then snugged back down, but not overly tight as this one acts as a pivot when making the adjustment. The outer screw is your adjustment screw. It can have an eccentric under the head, or the outer part of the points base may have a partial slot, which by using a flat pointed screwdriver, with this blade in the slot and the other side of the blade in a corresponding slot in the timing base, you can twist the screwdriver, allowing the movable points arm to be adjusted for it's opening, which is usually .020". You can use a set of flat feeler gauges, or better, the round style used for gapping spark plugs.

In setting them, use the feeler gauge of the proper thickness and insert it between both points contacts. Move the adjustment screw to where the gauge will just slide in and out without any movement of the movable arm of the points. When you are satisfied with the setting, retighten the inner pivot screw.

To adjust the points some versions have a "inspection hole" in the top of the flywheel, if so, you do not have to remove the flywheel but can adjust the points thru this hole. If your motor is a model that does not have this inspection hole, then the flywheel will have to be removed for the points adjustment. Here you may have to eyeball the high part of the cam and rotate the flywheel by a guestimate, remove it and take another peek. You may even (with the spark plugs out) be able to by carefully using a Crescent wrench against the key, rotate the crankshaft. BUT remember always rotate it in the direction the motor will be turning when running CLOCKWISE.

All OMC models that utilize points, will have the points set at .020. This point setting is usually stamped on the armature plate under the flywheel, or on the inside of the flywheel, so if you remove the flywheel you can see this setting information.

If you do need to replace the points, you will need to remove the flywheel however. On some of these models (especially the early models) they may have a spring loaded cam on the crank shaft. Or with the flywheel off, remove spring to install or set the points then use a thin screwdriver to hold the cam down while putting the flywheel 'mostly' on. On these if you do take the flywheel off, you may find it hard to get the flywheel back on because it is hard to get this cam to stay down while reinstalling the flywheel. (1) Use screwdriver to hold the cam down while putting the flywheel on, and if you're quick, it works. You may wish you have an extra set of hands though, or call a buddy over. (2) Or turn the shaft/cam to where it is just short of starting to open one set of points. Then the cam will slide down without interference. Now your ready to torque it on. Not too bad once you get the hang of it.

Another Johnson motor, the TS and TD20 to 26s use "Tower" type points that use a push rod, which are totally different.

One old time mechanic had a suggestion. If you are setting the points with the flywheel off on the above type, you may find that holding this cam down while setting the points is a bother. You can made a short piece of tubing to hold the cam down while setting the points. The flywheel nut holds the tubing down, tubing holds the cam down.

Double check your points gap, .020", anything dramatically more or less may throw timing off enough not to fire. These need to be set at the highest part of the cam lobes and if off just a slight bit, can effect the timing.

1974 thru 1976 : The 9.9/15hp motors have transitioned thru 4 electronic ignition systems. The first 3 years from 1974 thru 1976 has a straight magneto setup with points and condensers, but does have external coils, which are energized by what's called a "Driver Coil" located under the flywheel.

First off for the 9.9/15hp, if you are doing any work under the flywheel, you should consider replacing the original white or black friction ring on the timing plate (actually called the bearing). The new brown ones #322435 are made of Delrin and the word is from a experienced mechanic that this really helps these old motors as they seem to be a tighter fit. John Gill explained the later brown colored one was a tighter fit to make the magneto plate have less slop, especially at idle, so the pull of the flywheel magnets against the coil would not cause the timing to jump around as much and give smoother low speed running. The modified throttle cam was to try and give more throttle opening when accelerating from idle so the engine would clear out quicker as it tended to load up with fuel/oil after long periods of trolling. The revised ring also helped stabilize the magneto plate with the electric start option.

If the motor has sat for a while the points may have gotten oxidized. This can be usually remedied by running a point file thru the point openings to freshen up the contact metal. This older ignition using condensers, if they start to break down, the motor can start, run for a while, but when things warm up, the condensers can begin to short out internally where the motor may die. You can crank until you are blue in the face but it refuses to start. Let it set for an hour to let these components to cool down and it MAY then restart. Time to change condensers.

If that driver coil (under the flywheel) starts to fail, is cracked, or starting to melt down, or whatever, there is a possibility that it would also operate when cold, but fail by shorting out when heated up by the running of the motor. Rarely does this coil go bad however.

Here I will make a distinction between points, condenser ignition and electronic ignition as for spark plugs. It is the experience of many that the pre 1977 OMC 9.9/15's had a very weak spark to begin with. OMC never did get this right until they went with Capacitor Discharge Ignition. But you give up some things to gain others and life expectancy of the power-pack could be one of them. If you are checking spark jump using a tester on these pre 1977 motors, I am happy with these if it jumps only 1/4". For some reason the recommended Champions plugs may foul out with very limited usage on the points/condenser ignition, especially if the motor is used for a lot of slow speed operation. It has been found that by switching to NGK B6HS spark plugs (and in the next higher heat range) the fouled plugs go away with the engine seems to run better. Note that these plugs are only recommended for the older OMC magneto ignition motors.

If you have to use Champions, then possibly the UL81C would be a second choice alternate which is the next hotter plug in the Champion line. The Champion QL77JC4's are for '77 and newer that have CD ignition, and will likely foul quickly.

It has been found that by going to NGK brand spark plugs and go up one hotter range of a plug to #BR6HS for the weaker magneto ignition systems of the 74-76 motors that you will get less plug fouling.

Also on these 74-76 motors IF you synchronize (or index) the spark plugs, this helps too: Some home mechanics who frequent i-Boats have come up with another twist to help these PRE 1977 motors out. "It is called "synching" or "timing" the spark plugs which helps too. You orient the ground electrode toward the intake ports when you torque the plugs, the tip of the ground electrode will then face the exhaust ports (RH side looking forward). This then allows the ground electrode to shield the tip of the plug from raw incoming fuel mist and prevent fouling which also gives better low speed trolling. Remember that the spark plugs are screwed into the head from the right side, leave the electrodes on the left (intake) side of the cylinder (on this small motor)".

So here, especially on these 74-76 motors (because of weaker electronics) if you synchronize (or time) the spark plugs this helps too, as mentioned above. Sometimes, you need to swap plugs to get them to line up at the right point when tightening, it's a trial and error thing. This alignment does not have to be exact, close may be OK. Sometimes, you need to swap plugs to get them to line up at the right point when tightening, it's a trial and error thing.

If the above information is hard to grasp, maybe I can explain it in other words. The best location for the spark plug would for the electrode (overarm ground attachment) to be directed rearward + - about 30 degrees. This would allow for the open area for spark to jump INTO the cylinder, inward toward the center of the engine.

   It is hard and confusing to use clock rotation because if the plug’s position in the side of the head, but probably the gap opening at 3 o’clock, (pointing forward) would be that location, if that makes sense to you.

   Use a felt tip Sharpie pen to mark the plug's porcelain so you can see where to stop tightening it such that it is aligned as described above, and repeat for the other plug. So on this, mark the side of the plug to match the overarm, which you can then see from the rear when installed.   It also helps to lightly grease the plug threads/washer before starting. Sometimes, you need to swap plugs to get them to line up at the right point when tightening, it's a trial and error thing. For those of you who do a lot of trolling, especially with magneto ignition motors, this can be a blessing in preventing fouled spark plugs.

   This synch trick came to me via 2-stroke motorcycle and Go Kart racers, it works for them. This is also how the new Evinrude E-Tec motor spark plugs are "Timed", but they have a injector diffuser pin that is the aiming point for the open section the the plug's gap. However they advise to grease the threads to help facilitate this method.

There is an aftermarket Sierra conversion kit available from NAPA or Car Quest that converts these early points and condenser type to electronic ignition. From the experience of a marine dealer that says it does not work well if it is being used for trolling motors, as it appears the RPM is so low that it does not give adequate ignition, plus it appears that you need to order 2, one for each cylinder.

Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

When replacing the points on the 9.9/15hp motors, be extra careful and INSPECT the new points by comparing to the old ones you took out. I fought one of my motors for more years than I care to remember. It would run, but not idle down and die at about 1/2 way through the twist grip throttle/timing plate movement. I do not remember how many times, I got so irritated and set it back for a later date and me to SLEEP on it. I FINALLY found it was timed 33.5 degrees fast. The points wear bar was overly long as compared to the one on the old set.

Before I removed one of the sets, I adjusted it to where the flywheel timing mark were on. I cleaned up a old set of points and installed them without changing the flywheel movement. Adjusted the points to where I just got a break in continuity. And then, rotated slightly using a multi-meter again checking for continuity to disappear. It was right on the proper flywheel mark. These flywheels have writing on the underside indicating a different timing mark for Electric start as compared to the Rope start models, WHY, I DO NOT UNDERSTAND. Using the new points it was in time with the E setting.

When looking at OMC points listing, the same points fit ALL their magneto motors EXCEPT the 9.9/15hp and over 40hp motors. I am sure somewhere along the line SOMEONE placed the wrong set in the box, or picked the wrong set off the shelf.

Also, check the stator/ timing plate for lateral play. Move the flywheel clockwise by hand and look for any jumping of the plate. Pull the starter rope checking to see if when the flywheel is rotating that the timing plate moves sideways when the flywheel is rotating. If it can wobble or move laterally, it WILL also change the point gap! If the magneto plates get worn and or possible play in the upper crankshaft bearing, sometimes a closer point gap can alleviate a hard to find high speed misfire. The slop in the plate and bearings can make the points open wider than what they were originally set for while the motor is running, changing the timing.

Another thing to check is the spark plug wires. They may have become hard or the insulation cracked. Check these wires for a tiny pin hole where they are clamped to the timing plate. It is very common for them to arc through there. Better yet, just replace them.

These driver coils are available as aftermarket items here in the states. But in other parts of the world, are not available, or shipping costs are prohibitive. One corresponder in Australia has found that by using just the coil off Tecumseh lawn mower engines and removing the metal core, that by clamping the OMC laminates together and filing the edges of these oversize laminates to fit inside the Tecumseh coil, he has a usable substitute.

Timing Plate : If you have to remove this timing plate, there are 4 screws that need to be removed from the top that attach the timing plate to the timing plate base. These screws are marked by the red arrows as shown below. Note that 2 of them also hold the coils in place. If you take it apart enough that the coils are loose, be sure that they settle down inside the small protrusions of the plate when you reassemble them.

IF the timing plate bronze bushing gets worn, where it has some wobble in any direction, since the points are mounted on it, while the breaker cam is mounted independently on the crankshaft, you can get a variation in the point gap, creating erratic running.

There is no replaceable friction ring on most of these motors. Here is a non replaceable bronze bushing and it is normal to have a slight amount of slop here. About the only way to tighten is to use a center punch then randomly punch into the bronze, upsetting it enough to tighten things. Or if you have the time and energy, you could make a THIN steel or brass shim, place it either around the base boss or inside the timing plate, lubricated with grease. If you venture into this, fit it first, maybe even epoxy it in none or the other.

Coils : If you get no spark, check the coils. You may have a corroded/loose wire from the coil to the spark plug or even a damaged coil as seen in the photo below

Inspecting Points & Cleaning : Points that have been run will have a frosty appearance where they make contact, and the contact area should be like half the total face or smaller. If they are frosted over the whole area, or the faces are not smooth, or the "frost" looks contaminated or dirty, clean them. Degrease them first if greasy our oily.

Best way to clean points is to take them apart and polish each contact individually. Use a strip of 400 grit (black) sandpaper, backed up with a strip of something such as a hacksaw blade, and polish them shiny bright. Make sure you remove all grit that may be left behind.

While you are at it, check to see that the movable points arm is in line with the fixed side. This may require you to bend the movable arm to ensure that you have optimum contact.

After reassembled and gapped, the last step is to pull a piece of clean, plain, paper between them to remove the last bit of whatever (yes fingerprints). Don't pull the paper all the way out because it may leave a bit of lint from the edge of the paper. Pull it a way and then open the points to release it. Last step is check the resistance with an ohm meter. Should be zero resistance. Not just low resistance, zero. Actually, if you got them clean as just explained, they will pass the resistance test.

Setting Points : This has been covered somewhat above, but in case I missed something, setting the timing just at .020" point gap only gets you in the ball park, enough for the engine to start and run. You may luck out and get it to perform quite well by just setting the points, but it may have to be perfectly synchronized for peak rpm and performance. This will be discussed in the "Timing" section below.

The tools required would be a medium size spade bit screwdriver to make the adjustment and a set of "feeler gages" to do the actual measuring. These can be just the thin metal shim type used for setting automotive type valves, But the best would be the wire type used for setting spark plug gaps. Loosen very slightly the points securing screw. Select the proper size gage and using the screwdriver to adjust the movable point arm. Select the proper gage and as you make a adjustment, slip the gage between the points contacts. When correct, the gag should just slip through with MINIMAL resistance. Retighten the securing screw and double check the setting, it it moved when you tightened the securing screw, go back and redo.

Inspect the location of the points rub bar against the timing cam located around the upper section of the crankshaft. The rub bar needs to be located on the thickest part of this timing plate. It appears that on just setting the points, it makes little difference the placement/rotation of the throttle/timing cam, however some may have the word "SET" stamped in the top of the timing cam.

Set the points as follows. Usually the flywheel key will be located in the thickest part of the eccentric breaker point cam, which slides down over the upper exposed end of the crankshaft. Rotate the crankshaft to where the flywheel key and or this thicker part of the cam is aligned with the fiber rub bar of the ignition points. Adjust the gap so that a .020 gauge will pass thru but a .022 will not. Should there be any question of the points being dirty (touching the contact with your finger would cause them to be dirty), clean them with a small brush and acetone or lacquer thinner.

NOTE 1: Should the operating cam have a small portion on it with the word "SET" imprinted, align this portion with the fiber rubbing portion instead of the flywheel key.

NOTE 2: Should the cam have the word TOP embossed on the top of it, that is a cam that could be installed upside down and this is simply telling the mechanic which side is up. It is not a position where one would set the top cylinder points.

The marks on the flywheel are 180 degrees apart from each other, one for cylinder #1 (top), and #2 (bottom). Since these motors are 2 cycle, there's two sparks per revolution of flywheel, one at each of the flywheel marks lining up with the one mark on the armature plate. There is only one timing mark on the armature plate, and 2 (or 4) marks on flywheel. If there's 4, there will be 2 'E' and 2 'R' for electric or rope start. Now to confuse the issue I have a 1974 that apparently has a unusual flywheel that has the 3 magnet inserts for the electric charging, (as compared to the 2 magnets for the rope start version). It does not have the electric start ring gear (but is lathe turned for it), but the emergency rope start notches are for a rope start flywheel. In timing this motor the points open on the "E" settings.

You may find new points have a coating of light oil so you may need to clean the contacts with lacquer thinner before you can get consistent readings and spark.

On motors of these motors the points have a securing screw with a little wafer type washer under it. And the condensers are held down by a similar but slightly longer screw. Do you want to know what happens if you get those screws mixed up? Use that slightly longer screw to hold down the points and it protrudes just far enough below the timing plate that it pushes against the bronze support ring, effectively locking the timing plate in position.

The point contacts seldom wear out, but it is the phenolic rub bar that activates the points that rubs on the timing cam that does wear. When it does the points gap becomes closer, changing things dramatically. There is a felt wick that lubricates this rub bar. It needs to be lubricated. For this I like to use a tad bit of the old Power Surge or reloading case lube. This is sticky enough to not get thrown off during the running & a little bit goes a long ways.

Setting Timing Using a Continuity Tester : This is called Static Timing. When you want to use a continuity tester (multi-meter), proceed as follows:

When fine tuning the points adjustment, advance the twist grip throttle to FAST as far as it will go.

Using this method, you are rotating the flywheel and essentially adjusting the points (using the tester) to where the timing is so that each spark plug fires at the proper time when the piston is coming up compressing the fuel to fire at the precise time for best performance.

My method in using the tester is to drill a 1/4" hole in the timing plate indicated by the red arrow in the LH photo below. There is another stationary plate below, so you need to drill thru both. This location is so that you can connect a short jumper wire (12") to the points screw, then feed this wire down thru then connect it your tester so you can rotate the flywheel and watch the tester needle at the same time. This with the throttle wide open as mentioned above.

In operation, it may be best to remove the spark plugs to make it easier to rotate the flywheel precisely.

Remove all the wires from the points so you are not getting any feedback from the condenser or driver coil. Set your multi-tester to the Resistance or Ohm setting. You can check to see if it is functioning properly by touching both probe contacts as the meter needle then should move to the right or against the peg. Attach the red meter testing wire to your wire coming from the points. Attach the black wire to any ground location on the motor. If the points are closed, the meter needle will read high against the peg as shown by the blue arrow in the LH photo below.

Install the flywheel aligned on the crankshaft key, but there is really no need to secure it with the bolt as you will be needing to remove it possibly (many times before you are finished). Rotate the flywheel clockwise (best so you do not disturb the water pump impeller vanes if moving them backwards).

When you rotate the flywheel, watch the meter then at the instant that the points open, the meter needle will drop back to zero. This is what you are looking for. Actually it is when they open that counts, not how far they open except that the two are related. The timing mark on the flywheel should be aligned with the timing plate protrusion shown in the second photo below. This protrusion has 2 points about 3/8" apart. If your flywheel mark is between them, you should be good. If not, then rotate the flywheel until the marks are lined up. Carefully remove the flywheel without disturbing the crankshaft rotation. Slightly loosen the point securing screw, then with a LARGER bladed screwdriver insert it into the point adjustment slot, you can slightly open the points to where the meter needle moves to zero. Replace the flywheel and check the marks again with the meter to verify. If you are not right, do it again.

The RH set of points (looking forward) are for the top (#1) spark plug. To verify this, with the #1 points just opening, the #1 piston should be at Top Dead Center. This can be verified by pulling #1 (TOP) spark plug, by using a flashlight, rotate the crankshaft clockwise until you can see the piston come up, go slowly and backtrack just after it starts down.

Points adjustment notch, using large screwdriver for leverage to adjust points on a rope start motor. Note the wire access hole in the timing plate

Now one bit of advise, in making the final point setting, there is no real need to have the points tightening screw very tight, but just good and snug. In making the final adjustment, if you have this securing screw snug, you do not really have to retighten it, but can move the point adjustment very slightly, slipping it for final infinite adjustment.

When you get one set of points set at this timing mark, move over to the other set and repeat the process. You may now want to purchase a small 1/4" plastic plug to insert it in the hole you drilled in the timing plate.

When satisfied, then re-install all the wires to the ignition coil, condenser and out to the individual coils. Replace the flywheel and tighten the nut.

With new points, set the flywheel mark to fire in the middle of the large fixed magneto plate mark, which is a tad on the retarded side, because as the point faces break in, that will advance the timing. You can re-check the timing and set it again once the engine has about 10 hours running time, as the points will be broken in by then and the timing will have stabilized.

Here the drilled hole to accommodate the test wire & the blue arrow showing the meter needle with the points closed	Here the meter needle is a zero indicating the points have opened. Note the throttle cam roller at the most advanced position of the timing plate.

Using a Timing Light : This is also called Dynamic Timing. The timing light will reveal bad points, worn upper crank shaft bearings and magneto plate as the marks will jump around and not stay steady, something static timing does not reveal.

The timing light will illuminate only the cylinder's mark on the flywheel you have it connected the power clip to that cylinders spark plug wire, meaning only one at a time, that way you can check and adjust each one independently.

Dynamic Timing is checked with a strobe timing light, engine running preferably in a test tank. The strobe will reveal any changes in timing due to a worn set of points, an intermittent condenser, a worn crank top bearing, or loose magneto plate. The mark shouldn't jump around with the timing light, it should stay where you set it statically. If it jumps, you may have some play in your armature plate, and that's a different issue.

Static timing will not show that, as it cannot test for when the engine us running. With a automotive type timing light, you will need to connect it to a 12 volt battery if the motor is a rope start version. If you have one of the old neon lights, you unplug the coil wire to the spark plug and put it inline without the battery.

Flywheel Problems : We have here a situation where the point breaker cam sets on the bottom of the exposed upper crankshaft. This is held in place by the bottom 1/3rd of the flywheel key. This allows only the upper 2/3rds of the key to engage the flywheel. I have seen it on (2) 1974 9.9s where the flywheel key repeatedly gets sheared off, but the rest of the key is intact inside the breaker cam. Both of these flywheels had apparently gotten slightly loose over time and the tapered hole wallowed out slightly where it was mated to the crankshaft taper. This left a slight ridge on the upper inner edge of the flywheel hole. Even if you tried to over tighten the flywheel nut, the flywheel could not be sucked down tight enough on the crankshaft taper to prevent future repeated key shearing.

My cure was to use a small 1/2 round file then carefully file off this upper ring (unworn metal) inside the flywheel hole. This now allows the flywheel to be seated ever so slightly deeper and snugger on the crankshaft. The later motors do not rely on this breaker cam and I suspect the flywheel hubs are made slightly longer to eliminate this problem.

Convert to Transistorized Ignition : Now if you are having problems finding new replacement parts for these old motors, there is an alternative. That is convert it to electronic transistorized ignition. Briggs & Stratton has been using this type of ignition on their lawn mower motors for years.

Most of these modules will simply bolt on, however you have to select the proper model. They use the magnetic voltage created from the flywheel magnet rotating around the coil. This can not be used with motors that have battery charging coils for electric starters, but just rope start motors. You need one module for each cylinder at a price of about $24 a module.

These also work great where the timing plate bearing is so loose that each rotation changes the timing plate location, which in turn changes the points setting.

Those who have made this conversion seem to be very happy with the results. One reservation was would there be enough electrical power at an idle/trolling speed to allow these modules to perform to expectations. There appears to be no problems in that respect.

There is more than one manufacturer, so you do have some options. But for more information on the Atom brand, CLICK HERE.