Mercury classic 40hp two stroke

A

aerobat

Master Chief Petty Officer
Joined
Jun 1, 2011
Messages
849
Hello friends !

I,m about to pull the trigger on a göetcher 14' with an mercury 40hp two stroke .

Not new to boating and its just an idea as a second boat for fun but honestly i do not know anything about this motor except its a 4 cylinder 40hp 2 stroke .

Searching the net gives me only little information about this motor .

Any ideas where to look more closely during inspection before finally deciding the purchase ? Any weak points on this motor ?

The boat / engine seems in decent shape for small money .

Thanks for any help !
 
jimmbo

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
14,453
It was introduced in the 1958 Model Yr. Basically it is 2 of the 22 cubic inch twins in one Block. Small Pistons and a short Stroke.
Crossflow Charging, Very smooth idling Motor
Last year of Production was 1996. 38 yrs is a long Run.

Post a Pic of it
 
A

airshot

Admiral
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Jul 22, 2008
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6,609
I have a 1982 model and it has been an excellent motor. Mine has the oil injection system which has been flawless. My friend is a motor mechanic retired, but claims they work very well as long as you keep using the same brand of quality two stroke oil. Mixing together cheap oils can cause some issues, so I have been told. Bought mine from original owner and always used Oennzoil so that is what I use.
Check the compression, check for lower unit leaks, and be sure all the fuel hoses are in good shape under the hood. Mine idles so slow you can almost hear each cylinder fire. Been very happy with mine !
 
M

Mc Tool

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racerone said:
It used to be a 50 HP.----Now prop rated at 40HP.-----One of the best they marketed.-----Do a compression test.
Click to expand...
Sounds like an interesting motor .
Seems a few motors from that era had a lot of cylinders for what is not a large motor , Honda's 6 cylinder 125cc and 250cc gp bikes and Ferrari 1.5 and 2.5L V12's spring to mind .🙂🙂
 
jimmbo

jimmbo

Supreme Mariner
Joined
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Messages
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Mercury used to basically add cylinders of the same Bore and Stroke
In the 50s they used the 20 inch Twin, doubles as a 40 inch 4 Cylinder, and in 57, added 2 more to make the first inline 6. Fast Forward to the 70s and the 33.3 inch Twin Bore and Stroke, used on the 40hp, was doubled for the 66.6 Inch Block used for the 800, 850, 80hp and 75hp. 2 more Cylinders made the 99.8 in block that was the Basis of the 1150, 1250, 1350, 1400,1500, 900, and later 90, 115, and 140. Pistons and Blocks varied. Early ones were all CrossFlow, Later 33, 66, and 99 blocks were Direct Charge, and some of those were Power Ported, which also required a different Piston.
The V6s never added more Cylinders, though there are Rumours of a V8.
Mercury did make a 12 Cylinder Outboard at one point, they used 2 V6s mounted beside each other, facing opposite directions, they were coupled together. They were Fuel Injected, as shown by the Silver Fixture on the Side of both Blocks. As far as I know, it never got past, the 'Can we do it' Stage
Here are a couple of pics of it. Next to it is Jerry Hale the Chief Engineer of the Mercury V6
Scan_20180210 -14.jpgScan_20180210-13.jpgScan_20180210-5.jpg
 
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A

aerobat

Master Chief Petty Officer
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Messages
849
Great information so far gents !

I will inspect the boat next weekend so then i will post a pic .

I believe its a 1992 model . Does it have the oil injection with tank ?

Its a fun idea , like said a 14 foot fletcher arrowflyte with this motor . Curious how it runs with it.

Yes , i think i will check compression . Obviously i,m hoping for similar results on all cylinders , but what numbers i,m looking for ? +100 psi is ok ?
 
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