1973 65 hp johnson?

blakespop

Recruit
Joined
Mar 2, 2009
Messages
5
I am new to boating, and just bought my first boat. Its a 1973 mark twain with a 65 hp johnson. I dont know anything about the boat. I was told it is called a runabout. It is 15 or 16 foot, tri hull, with a walk threw windshield. I would like any input on the boat or motor. The boat needs a battery and gas line, so I didn't hear it run before I bought it. I was told it was ran last year and runs good. (Guess I will find out, LOL) What should I do before trying to start the motor or taking my family out on the water? Is this boat and motor good and reliable to be so old? Any advice will be appreciated. Also how do I mix the fuel, What ratio? Thanks
 

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,518
Re: 1973 65 hp johnson?

I have heard far too many people say that everything is well with the boat and engine while trying to sell it.But now there is a battery missing and that is why they cannot start it for you.......
I hope for your sake that you were not taken for a (boat) ride.
I would it to a knowledgeable person to check compression,impeller,ignition, carburetor and lower unit.If all is well,take it out with somebody who knows what he is doing and learn the ropes.Once you feel confident running the boat you can take it out by yourself with your family.
The age of the boat and motor are not very important.Many boats and engines have not been used for more than 20 hours per year.
Your fuel mix is 50:1.
Good luck.
 

blakespop

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Joined
Mar 2, 2009
Messages
5
Re: 1973 65 hp johnson?

thanks for the advice, I am going to check the compression and rebuild the carbs myself to save some money, The other things you mentioned, I guess I will find someone to look over them for me. Thanks again!
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: 1973 65 hp johnson?

The one serious problem we had with that particular model was that they cannot stand even a hint of overheating. When they run hot, the exhaust cover baffle plate warps and then water squirts into the exhaust ports, doing catastrophic damage. Not meaning to imply that has happened to yours, just be aware. And make sure the cooling system is up to snuff.
 

rolmops

Vice Admiral
Joined
Feb 24, 2002
Messages
5,518
Re: 1973 65 hp johnson?

how do I check the cooling system?

You cannot check the cooling system without taking it apart.The good news is that you do not really have to check it.Overheating will show on the outside of the block and exhaust cover.If the paint looks burnt OR very fresh(repainted) then be wary.Most engines of that vintage are extremely resilient as far as over heating is concerned.
 
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