Help needed identifying GS550 model

[DKGS]

Dear all,

I need help identifying the model and year of the Suzuki GS550 that I am working on.

I have taken over the bike from a colleague's father. He had been working on it for some years, but without getting it to run. Now I have taken over, and as I already have done a similar job on a Suzuki GS850, I thought that this would be easy, but I am in trouble from the get go. My first issue is identifying exactly the model and year of the bike that I am working with, so I can start ordering some parts.

Here are the different clues to the mystery:

• Spoked wheels (not alloy rims)
• Double front disc brake
• Rear drum brake
• Kick starter
• Kokusan points (two condensers, with the "bottom" of the cylinders facing out)

The frame serial number is GS550D-10XXXX, but when I look that up, the model and how the model is described does not seem to match with what I am looking at.

I am based in Europe and I expect the bike to be a European issue as well and that might be the reason why this does not match any of the microfiche that are available on US websites.

It could also be a Frankenbike, and that could be the reason that it is hard to identify. For instance, it has a regulator / rectifier in one single unit now, but the way that it was mounted seemed “unofficial”, so it might have been born with separate regulator and rectifier units, and then replaced with a single reg/rec somewhere down the line.

Any help would be highly appreciated.

Thanks and best regards

Michael

[Nessism]

What parts do you need? Suzuki didn't change the bike a whole lot year over year, so most '77-'79 parts will work for your bike.

[rphillips]

Not remembering a spoked wheel GS with dual front brakes. But me not remembering is getting quite frequent these days..

[Rijko]

Welcome Michael.

This may help :

[Rijko]

The frame serial number is GS550D-10XXXX

going by the 6-digit 10XXXX chassis number, it could be a 1977 GS550 B or 1978 GS550 EC model.

[Rijko]

If you check out this page, the first model 1977 came with a single front disc brake.
In 1978 the GS550 went from wire wheels with single front disc, to wire wheels with dual front disc, to cast wheels with dual front disc.
Even switched from drum brake to disc on the rear.

The second version of the GS550 for 1978 was available in two versions, with a single brake disc at the front, as in 1977, or with twin discs for better braking performance (compare the pictures below). The model was released in Japan in April 1978.

In August 1978 the GS500E was launched, replacing the GS550. The model had light alloy wheels and a disc brake even at the rear. Apart from the wheels and the brakes, the models were quite similar.

Do you have any more info, maybe a manufacturing date on the VIN plate/sticker or date on the bike registration papers ?

[rphillips]

Interesting read Rijk. I'd not seen that. Always wondered why most GS front spoked whls. were drilled and tapped for brake rotors on both sides.

[Rijko]

Interesting read Rijk. I'd not seen that. Always wondered why most GS front spoked whls. were drilled and tapped for brake rotors on both sides.

Suzuki used that front wheel hub in 1973 on the GT250, GT380, GT550 and GT750.
(Using a single disk)
And used it on several later models before the GS550 came out.

My guess is that they found it easier/cheaper to stock just 1 hub (drilled on both sides).

[DKGS]

Dear all,

Thanks for all your input

Rijko Ill try matching the wire diagrams of the 1977 GS550 B or 1978 GS550 EC with what I have in the garage. I have found that the wiring diagrams differ quite a lot from model to model. Also between US and European models of the same year. Thanks.

Nessism For now I have gotten by with an aftermarket gasket kit, but I feel that I am getting closer and closer to the "Vintage Motorcycle Money Pit", so it would be great to get the orders right in the first go.

rphillips I know how you feel, but I am sure that I will soon forget, so all it good

BR M