Mercury 115HP outboard Rebuilt

I want to make sure I'm getting the right parts.

This is my first boat so I do not know much about them but I'm mechanically handy.

Every where I look for information, my information does not match with the information in the internet.

I have 1979 Hydra Sport Mercury 115HP with the serial: 53154669
It's a 4 cylinder inline.
Question 1. Does the serial number exist with this boat and motor?

2. How can I tell if it's a four or two stroke?

3. Do I need a mix with the gas?

My title for the boat under fuel says "GAS"?
4. does someone know what the torque spec is for the connecting rods?
5. what is the torque spec for the crankshaft?

thanks for any help above...

Re: Mercury 115HP outboard Rebuilt

Kaporal said:

....I have 1979 Hydra Sport Mercury 115HP with the serial: 53154669
It's a 4 cylinder inline.

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That serial number has one too many digits. I suspect you double tapped the 6, in which case the engine is a 1979 [size=+1]6 cylinder[/size] 115hp. 4 cylinder 115hp engines didn't start until 1989.

Kaporal said:

Question 1. Does the serial number exist with this boat and motor?

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With the boat, no. The engine serial number is just that, an engine serial number.

Kaporal said:

2. How can I tell if it's a four or two stroke?

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Got valves in the cylinder head? Got a sump full of oil? It's a 2 stroke. Only Honda were making 4 strokes in 1979...

Kaporal said:

3. Do I need a mix with the gas?

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Yes... (Ratio is 50:1, use a TC-W3 rated oil). If you find something with the word "AutoBlend" on it in the boat that appears to be hooked up the the fuel lines.... Pull it out and bin it, FAST!

Kaporal said:

My title for the boat under fuel says "GAS"?

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Good....

Kaporal said:

4. does someone know what the torque spec is for the connecting rods?

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180in.lbs.

Kaporal said:

5. what is the torque spec for the crankshaft?

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Crankshaft just sits in the crankcase halves. Crankcase bolts torque is 200in.lbs.

Kaporal said:

thanks for any help above...

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You're welcome.

Re: Mercury 115HP outboard Rebuilt

Thanks "achris"
The motor is a 4 cylinder as it is all taken apart.
I bought the boat from a guy that took the outboard apart and after a year he didn't have the time or the know how to put it back together.
I need to replace one piston and the rest of the rings.
I bought the gasket rebuilt set but the piston that came had two rings and the pistons that are on the crank have three rings, so I didn't take the piston.
The guy at the store didn't show or had a different piston to match the one I have.
So thats why I wondered if the serial went with this outboard.
thx..

Re: Mercury 115HP outboard Rebuilt

It sounds like you have a 80/85 hp engine as the new style 115(4cyl) are offered in 2 ring only. If it has a flat top its a new style something and if ithas a dome(eyebrow) it a old style engine or a Johnrude V-4

Re: Mercury 115HP outboard Rebuilt

Achris you are absolutly correct. it is a six cylinder.
I took every thing out of the box and seen that two connecting rods with pistons were off of the crank (p2 & p5). I hadn't looked at it too closely, I though that space was for the crank supports.

thx..

Re: Mercury 115HP outboard Rebuilt

My bad. I hadn't considered that it wasn't a 115. In 1979 the 4 cylinder was either a 50hp or 80hp. Easiest way to tell is the piston diameter. 50hp is 2.56", 80hp is 2.87".

2 ring and 3 ring pistons can both be used in the same engine. You can even have one (or more) cylinders oversize. The piston manufacturers make all the pistons the same weight, regardless of the number of rings or the piston size....

Chris.....

Re: Mercury 115HP outboard Rebuilt

Kaporal said:

Achris you are absolutly correct. it is a six cylinder.
I took every thing out of the box and seen that two connecting rods with pistons were off of the crank (p2 & p5). I hadn't looked at it too closely, I though that space was for the crank supports.

thx..

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ROFLMAO...