Outboard Motor

Laing's Outboard Newsletter February 2002
Outboard Motor | Thursday, 04 December 2008

The evolution of the outboard motor continues. Four stroke outboard motors are gaining in popularity, as manufacturers continue to improve the technology and overcome many of the advantages two strokes have always had, such as light weight and high horsepower.

Honda and Yamaha have been making four strokes for years, but 2002 marks the introduction of the big V-6. Honda is selling both a 200 and a 225 HP engine, both based on a 212 cubic inch V-6 60 degree block. Yamaha's big motors are also 200 and 225 HP, based on a 3.3 liter 60 degree V-6 block, with double overhead cams, 24 valves and tuned intake tubes. The weight is a modest 580 lbs, comparable to a similar 2 stroke outboard.

Mercury, long known for its 2 stroke engines, is the world's largest 4 stroke manufacturer, offering 55 different engines from 4 HP to 115 HP.

Suzuki has come out with the DF140, a 4 stroke 4 cylinder engine weighing only 410 pounds. It has dual overhead cams and four valves per cylinder, with a two stage cam drive and offset driveshaft that make for a smaller overall engine.

Ironically, though, it is still the conventional 2 stroke that dominates industry wide sales. The market share breaks down as follows: 70 percent for conventional 2 strokes, 20 percent for 4 strokes and 10 percent for direct-injection 2 strokes.

QUESTIONS AND ANSWERS

A reader asked a question regarding last issue's discussion on pulling flywheels. He asks: Have you ever looked at the top of the flywheel on a Johnson TD-20? I do not want to disengage all those little springs in the rewind mechanism attached to the flywheel to get to the three screws.

Well, on most motors that have the springs and pawls on the flywheel, you don't have to take the mechanism apart to pull the flywheel. Those clever engineers used a special flywheel nut that has a shoulder on it that pushes against the bottom of the pulley when you loosen the nut. This acts as its own flywheel puller and actually makes it easy to remove the flywheel.

Keep those questions coming.

Service Department

Last month we talked about pulling the flywheel. this month we will talk about servicing what you find under the flywheel.

Most small older outboards have one set of coil, points and condenser under the flywheel for each cylinder. All of these components must be in good condition in order to get a strong spark to the spark plug. Unfortunately, it is difficult for the amateur to test the coil and condenser. There are special testers for testing these items, and the tester is becoming more difficult to locate. Years ago, you could carry your coils and condensers into any marina and ask them to test them for you, and they would gladly do so. But that is not generally the case anymore. We will test any coils or condensers at no charge, either if you bring them in or mail them to us.

This being the case, it is best to just replace the points and condensers if they are available. They can usually be found for most outboards built after WWII. If your motor is older than this, or you cannot locate the parts, you can usually get by with taking the points out and polishing the contacts with superfine emerycloth, cleaning them well and reinstalling them. There is no way to tell if a condenser is any good by looking at it, and a weak condenser will prevent you from getting a good spark. In most cases, it is enough to locate a new condenser that is similar in design, as long as you can make it fit. It is sometimes obvious if your coils are bad. If the outer casing is cracked, as is common on older Johnsons and Evinrudes and some others, replace them. If the coils look OK, test for spark as discussed in an earlier issue, and if you get a nice strong spark on your spark tester, the coils are probably OK.

One consideration is what your plans are for the motor. If you are intending to get the motor running and put it on a boat and use it, I would recommend installing new coils if you can get them, regardless of what the old ones look like. From our experience in the shop, good used coils may put out a spark of around 5-10 KV, which is enough to run the motor, but new coils will put out a spark in excess of 20 KV, which will make a big difference in how the motor starts and runs.

Next step is to set the point gap. Most outboards call for a gap of .020". Turn the crankshaft until the points are at their maximum opening, and set them. Then turn the crankshaft 180 degrees and set the other. On some outboards, especially the 10 HP Johnson and Evinrude, it is easier to set the points with the flywheel on, utilizing the hole in the top of the flywheel.

Hopefully, everyone now has a good spark to the spark plug, which is the most important element of getting an old outboard to run. If you have a newer outboard without points and condensers, call for servicing information. If you have specific questions, email me. Next month we will move to the carburetor.

We have aquired a limited supply of Tillitson carb parts for the West Bend outboards. These parts include carb gaskets kits and needle and seat assemblies.

Following is an excerpt from a Mercury service bulletin dated August 12, 1950.

SUBJECT: Throttle Position KG-7

High speed operating position of the spark lever is extremely important on the KG-7 Hurricane. This adjustment will vary considerably, depending on the type and weight of the boat being used. Those owners using Quicksilver lower units on comparatively light hulls will affectively operate the engine with the spark throttle at the extreme advance position.

When heavier type boats with engines employing standard lower units are used, the extreme advance position of the spark will cause preignition. This will noticeably affect the performance of the engine causing it to slow down.

Advise all owners to follow these instructions for correct operating position of spark lever.

1. Start motor and allow to warm up for several minutes at slow speed.

2. Slowly advance spark lever to extreme fast position.

3. From this position slowly return the lever toward "slow" until the engine begins to lose speed.

4. Next advance the lever toward the fast position approximately 1/4 to 1/2 inch. This will be the correct full speed operating position. Mark this position on the protector rim for future operating reference.

Never use more spark advance than just what is needed to maintain maximum R.P.M.

This month's motor is Chris-Craft.

Chris-Craft outboards had a short but interesting history. I will not get into that here, but production of this popular motor came to an abrupt end in 1954, some say because they bore too close a resemblance to Mercurys in certain ways.

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