Johnson GT 150 high performance racing engine

[flippin_nh]

I just bought this outboard and I am trying to figure out what year it is, The serial number is 5984436 The boat it came on is a 1987. The gentleman I bought it from bought it new back in November of 87 The motor was bought through the owner or one of the big shots at Skeeter boats. I have a manual but the cover is gone and I can't find a year or a model; number anywhere in the book. One other thing the gas / oil mixture is 25 to 1 which I believe is not normal for outboards back in the late 80 early 90. Anyone help me out on this.

[THE WITCHDOCTOR]

Should mix 50:1

[Neveredge]

There is no such animal as a GT150 high performance racing motor.

The GT150s are basically a 150 that pushes the allowable 10% hp limit. They make about 165hp at the prop.

The race engines were the 2.6GTs and they do require 25 to 1 oil mix. These motors made about 230 hp in stock form but they were not made in 87.

Does your motor have an exhaust bubble on the back of the engine or is it flat?

Better yet, what are the part numbers on the heads?

If you can find the model number we can tell you exactly what you have. It will start like this "J150stl-----" or "j235stl---------"

[ChampioNman]

If you look on the left side of the transom where the motor mounts you should see a tag. If it is an '87 GT it will read, J150STLCUR.