Need help with GS550 engine ID

[xkaes]

I have TWO GS550 bikes and THREE GS550 engines. My problem is the THIRD engine -- which I don't need.

I bought my first GS550 new in 1977 (a GS550B) with engine # GS550-106214.

A friend later gave me a used 1978 (a GS550C) with engine # GS550-146274.

Another friend, still later, gave me a used GS550 engine # GS550-171764.

I'm trying to figure out what bike, model and year the THIRD engine came from. It obviously was made after the 1977 & 1978 engines. I do not have the frame.

Is there any way to determine -- or estimate -- the year that the engine was made from the engine serial #? I want to sell it, but it would help if I could describe it better than "A GS550 engine"

[steveb922]

Sounds like a later model engine. Basically 1980-82 550 engines had no kick start, and a head suitable for CV carbs. Probably transistorised ignition, as opposed to points, although the introduction of this varied in differing markets. I can't remember my own engine numbers off-hand, but if no-one comes up with accurate info in the interim, I'll take a look tomorrow.

[xkaes]

Thanks for the info.

I was guessing 1979 because there is a 40,000 difference between my '77 and '78 engines -- and 25,000 difference between the '78 and the unknown engine.

But, this engine definitely does NOT have a kickstarter -- so it must be a 1980, as you say, unless some of the late 1979's also lacked the kick start.

Anyone know for sure?

[Big T]

Measure the intake port inner diameter

[Nessism]

The lack of kick starter is a clear sign that it's a 1980 or later.

[ukjules]

Prob too late but I agree 1980 prob a 550et ? like mine.