GPZ550 Newsletter 01/06. 1980s used bikes—determination and grit? Front and rear 18-inch wheels really are something special~

Once the GPZ550 gets sorted to a certain point, it settles down—that’s just how it is.

This is the first GPZ 550 newsletter of the new year.
There’s plenty I’d like to do, but with the move coming up, I can’t spend all my time working on bikes.
Actually? I think the GPZ550 is pretty great~ —I suspect quite a few people feel that way.


In my case, there weren’t any major issues to begin with,
so I was able to get it running and enjoy it in a short time.
Even with a bike this old, of course if it’s in good condition,
you can ride it without any problem.
But still, a bike that’s been around for 40 years is always sitting right next to risk.

The key to used bikes: stock up on fuel tanks and bodywork

In my case, the GPZ 550’s tank was completely rusted and
full of pinholes.

Honestly, repair is totally doable,
but when you think about “repair labor, rust removal and coating costs, and repainting,” it’s
faster and more reliable to just buy a good used one.
This works because used parts are available on the market, but
with oil-cooled Suzuki bikes you sometimes have no choice but to use them.
*Suzuki really is a pain to find used parts for!

“When you buy a used bike, have a second set of bodywork ready to go.”
I think that’s important.
*If reproductions exist like they do for the Zephyr, you won’t need this.

A motorcycle’s main harness is extremely important

In my case, the condition was good, so I’m reusing it as-is.
I’ve never seen a reproduction main harness for the GPZ 550.
However, the sibling GPZ 400 does have reproduction harnesses available, so
I think using that going forward is the way to go.

You really need to check whether these parts exist before buying a used bike, or you’ll have a bad time.

Small things like turn signal relays can be swapped for modern IC versions, and
OP power and such can be tapped using a D Unit WR, making things very simple.
I keep the ignition system original and use my favorite plasma booster.

Swapping the turn signals to IC makes them light up with snappy response.
Adding a plasma booster
improves starting and overall smoothness, making it run really well.
*If the ignition system is fine, I basically don’t install Watanabe.
Just adding a few modern electrical components makes a big difference in comfort.

Kawasaki has the type of ignition coil where you can swap the plug cord.
The old ones get so stiff you’d think they’re positive.
If you’re thinking about reliability, you should definitely replace them.

Important: carburettor overhaul parts and intake manifold availability

For the GPZ 550, these parts are supplied abundantly, so you’re in good shape.
However, things like jets inside the carburettor are discontinued, so
if they’re shot, it gets a bit rough.

Buying a used motorcycle and finding out the carburettor doesn’t work right away is pretty harsh.

If you wanted to adapt something like a Zephyr CVK, I suppose it could work, but
when you think about installation and tuning, it’s not something you can just jump into.
It’s safer to find one that’s in good original condition.

I’d rather leave the engine out of this

Buying a used bike and having to tear the engine apart right away
is pretty rough, you know?

When you pick up an older motorcycle, you should check the compression first.
And then oil leaks around the engine.
I can tolerate a little seeping, but if it’s dripping steadily, that’s a bit concerning.

When you buy an old used bike, it’s probably a good idea to check the compression first
and think about whether you can live with it.

You want to save engine overhaul and tuning for later fun.

Final thoughts: maybe it all comes down to determination and heart

That said, you can end up spending endless money and time, so
in my case, I try to buy bikes that are “as original as possible” and “not restored.”

Modern techniques are really amazing— “frames that look ready to return to the earth come out sparkling.”
I’m sometimes amazed at the level of condition misrepresentation, almost like age fraud.

If they properly removed the bad spots and finished it well, that’s great, but
just painting over corroded areas and having the frame snap off a few years later is something you hear about all the time.
The used bike market is genuinely scary, so “the prettier the finished bike, the more you need to check it.”
*With bikes like that, you can’t go wrong buying from a trustworthy shop that publishes their work process.

If you’re worried about an old bike, a Zephyr 550 or thereabouts is a safe bet.
With a GPZ550, there’s a higher chance you’ll run into some headaches.

Still, front and rear 18-inch wheels really are nice~ It’s a bike that makes you feel that way (*´ω｀*)