How to tell apart a 2 stroke or 4 stroke

[Franco55]

I'm a very new boater and the small craft I have is a 16 footer. It is a 1970s era boat. It has a Johnson GT100 outboard engine. I don't see any markings indicating a real number or any identification except the cover which says, Johnson GT100. How do I tell if it's a 2 or 4 stroke? It has a small reservoir that has oil. A container for gas, that is close to the oil reservoir. I can't see an oil filter on the engine. Can anyone help, it will be much appreciated.

 

[ondarvr]

From just the outside of the motor someone that wasn't familiar with the brands and their offerings would have a tough time knowing the difference.

Before about the year 2000 everything was 2 stroke, yes there were some 4 strokes around, but that was the beginning of the end of 2 strokes, after that all brands leaned hard in the 4 stroke direction except Evinrude.

Yours is a 2 stroke.

 

[V153]

Pics? ...

 

[racerone]

GT 100 is a 2 stroke.----Best to verify that oil injection is in service and working properly.----A compression test for later reference is a good idea too.

 

[flyingscott]

Easiest way to tell is pull the hood and see if it has a timing belt. Yours is definitely a 2 strk.

 

[V153]

What year is the motor?

 

[Franco55]

Thanks very much for the replies! I will get pictures to you by days end. Again it is much appreciated.

 

[Franco55]

Hope this works!

 

[thatone123]

If under 20 hp a 4 stroke is an old fat heavy weak ol' lady so quite and less fuel used coz no get up and go.

 

[Franco55]

Sorry but I can't post a picture for whatever the reason from my phone. I will try from my iPad tonight. Thanks for all your replies. Boaters are great.

 

[Chinewalker]

GT100 is a 2-stroke, V4 crossflow design. Made several years in the late 1980s, possibly early 1990s.