2 stroke or 4 stroke

[grant92]

I know nothing about boat motors! I have a 1983 Mercury 150 Blackmax. Is this a 2 stroke (pre-mix fuel) or a 4 stroke. I thought all motors up to the late 80's were 2 stroke. Thanks in advance.

 

[Silvertip]

Re: 2 stroke or 4 stroke

You have a two stroke. The tip off as to whether an engine is a two stroke or four stroke is to remove the cowl. If you see an oil resevoir on the side it is two stroke. If there is a separate oil resevoir at the stern of the boat with a hose going to the engine it is also a two stroke. If you have to mix oil with the gas you also have a two stroke. Two strokes don't have an oil sump like a four stroke. If you see a dip stick and oil filter like the one on your car or truck, and you have four stroke. Oil is added to the crankcase on a four stroke and must be changed just like your car. But the easiest way to tell is by simply looking at the cowl -- it generally says "Four-Stroke" whereas two strokes do not say "Two Stroke".

 

[grant92]

Re: 2 stroke or 4 stroke

THANKS FOR REPLYING!! Verey helpful. By chance would ratio be the same as most 2 stokes at 50:1.

 

[j_martin]

Re: 2 stroke or 4 stroke

It may or may not have oil injection. If it does, there'll be a reservoir under the housing with 2 cycle oil in it, as well as a nurse oil tank, usually about 3 gallons in the boat with a double hose to it. In that case, the oil is put in the nurse tank. It is mixed by the engine just before the carburetors.

If none of that gear is on your engine, then you mix TCW-3 oil with the fuel at 50:1

Do yourself a big favor. Get an owner's manual. It has all you need to know, from operating procedures, PM lubrications, etc. If you plan to work on it, get a factory service manual.

hope it helps
John