Older Boat - Need Help

[Austin]

I recently got a older boat a 1972 glastron with a 100 horse evinrude motor. The boat is in pretty decent condition considering it's age. But the motor just doesn't seem to have the power that it should, even for it's age. Is there anything I can do to give it a boost or what would be the best plan of action? The family wants to be able to use it to pull a skiier or tube as well as catch a few walleyes. Any info is greatly appreiciated.

thanks

Austin

[VMS]

1. Get a can of sea-foam, or Mercury Power-tune. Get the engine warm and follow the directions on the can for placing directly in the carb. Let it sit for about 30 minutes, then take the boat out and open it up.

this is a quick way to clean out any gunk that may have been built up in the main combustion chamber of the engine. Then with new gas, add another can of seafoam to the tank which will help to clean the jets of the carb.

If you have enough time and are mechanically inclined, I would suggest doing a compression test on the cylinders...see if they are within tolerance levels of each other. Then, if you have time, remove and replace the head gaskets...retorque and run the engine a bit to re-seat. Then check compression again. Hopefully it will have gone up some.

A new water impeller and thermostat (if motor has one) would be a safe thing to do as well. this will hopefull keep the motor running cooler and this could hlep too..

Just a few suggestions to start out with..

Steve

[Austin]

Any Suggestions ?

[PerchJerker]

Everyting VMS said is good. I'd start with cleaning out / degunking the motor, next I would check the compression before spending any money on the motor.

Other thoughts ......

New plugs and make sure they are the correct plugs for the motor.

Talk to a prop shop to see if they think you are using the right propeller for the boat.

Does the motor have power trim? If so, are you trimming it down all the way for holeshot? If it doesn't have power trim, should you set the trim tab lower .... or add an aftermarket trim kit?

A couple other things for you to consider.......

1. An outboard from that vintage was rated at the powerhead, not at the prop. When it was new it would have been the equivalent to one of today's 75 / 80 hp motors.

2. How heavy is the boat, and is any of the wood or foam waterlogged and adding a lot of weight?

Good luck with your boat, I hope some of this helps.

[sparcebag]

An outboard from that vintage was rated at the powerhead, not at the prop. When it was new it would have been the equivalent to one of today's 75 / 80 hp motors.

I've been thing all these years it was the other way around! I had a 50HP Johnson 1958 it was HUGE Heavy! got a newer 75 and it was no more powerful than the 50.the 50 would pull 5 skiers out of the hole (good skiers),the 75 worked hard to get 4 out & plaining!

[beeonkey]

The compression test is probably the first thing if you have a very week cylinder don't waste the money on the cleaner the damage is already done.

If you have a tach. on the boat what is the rpm's at full speed? Then check that with what red line is for the motor. Look at what pitch the prop is and try to set up a prop that red lines or just above and you will have all the power the engine will give. Even with an old 100 you should get 32-37 out of it. I can remember we had a '72 18 1/2 foot Larson with a evenrude 85 on it and it pulled skiers just fine. About 32 if I remember correctly.

Good Luck

[dkf]

Quote:

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The compression test is probably the first thing if you have a very week cylinder don't waste the money on the cleaner the damage is already done.

If you have a tach. on the boat what is the rpm's at full speed? Then check that with what red line is for the motor. Look at what pitch the prop is and try to set up a prop that red lines or just above and you will have all the power the engine will give. Even with an old 100 you should get 32-37 out of it. I can remember we had a '72 18 1/2 foot Larson with a evenrude 85 on it and it pulled skiers just fine. About 32 if I remember correctly.

Good Luck

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A compression test is a must. You may need to have the motor freshened up. Good news is its an Evinrude so parts are available. If compression is good check the motor for cracked coils, leaks, torque the head bolts, replace plugs, fuel filter and rebuild the carbs and have them adjusted. Be careful what dump you run through a 2-Stroke. (Cleaners) 2-Stroke require oil for lube and running large amounts of cleaner through them can wash the pistons.