Air-cooled 4-cylinder hidden gem? ZEPHYR550, what is it really?

April 2023
“I bought it on impulse”

Having a place to keep it is scary…

When buying something, more than cost-benefit analysis
“The one that got away is always bigger”
Choosing things without regret
is important

I live my days gambling
CMS parts list

KAWASAKI ZR550B9 ZEPHYR 1998 FG
Even the final model is from ’98

Although the build quality is good
that’sa 25-year-old vehicleit is.
Definitely a classic bike

Seemed sweet but wasn’t?
Even though the condition was good, there were
some subtle issues.

The ignition coil cord
clicking
isn’t misfiring exactly
but it doesn’t spark crisply

This subtle cord replacement makes a noticeable difference
it had deteriorated for better or worse.

Since it’s an export model for emission-controlled regions
“it’s incredibly lean”
it’s extreme.

When the carb is restricted
it runs poorly until warmed up
the idle is almost out of sync
the feeling is terrible
“Opening the PS makes a dramatic difference”
since it’s adjustable
I’d definitely like you to experiment with it.

50PS/10000rpm/179kg

Even people riding bigger bikes probably

hmm!
“This thing really goes, doesn’t it?”

would think

it runs quite vibrantly…
honestly, it’s quite fun.
ZEPHYR550
dry weight 179kg
50PS/10000rpm
4.1kg-m/6000rpm

RVF400
dry weight 165kg
53ps(39kw)/12500rpm
3.7kg·m(36.3N·m)/10000rpm

That’s how high-spec the ZEPHYR550 is
(*´ω｀*)

The foot placement is so good
flat
“Rossi dismount”
is possible.

I likearound 10,000 rpm redlineit’s easier
same as bigger bikes

continuously revving feels tedious in city riding

Opened it up
and tried it!

Oh, it’s slow…
No top end “missing teeth”

The tach goes up but the speed doesn’t increase
seriously, shock

If I was just riding around the area
it would’ve been fine
I have to order that old-school thing

Still available from America
the top end becomes a different beast.
*The original was just too bad

Thanks to this, I can ride endlessly on the bay shore
and tour with liter bikes
that kind of dramatic change

can’t start without it
that kind of dream item

The fork is
squishy

Common with mid-displacement and below
squishy fork

initial adjuster is naturally necessary
when you check the rate…
it’s that low? kind of feeling

I haven’t written it on the blog
SS Itou’s 0.8kg/mm
I’ve installed (*´ω｀*)

it’s quite firm.
You need to balance the fork oil too, but it’s really good.
Or rather, it becomes normal.

Whoosh~
engine stops

It’s a really subtle symptom
when you engage the clutch it goes “whoosh~” and stops
same thing even if you rev and engage

it’s misfiring…
jiggling the sidestand sometimes fixes it
it’s a really subtle symptom
but this kind of thing happens when bikes get old

Various things catch my attention

Since it’s only 550, mostly wide open
number of shifts × full throttle
= tedious
First, I shortened the final drive
I haven’t written it on the blog
but I dropped the front one gear.
it works quite well, even on the bay shore

with a bit of high throttle, the throttle opening issue is also resolved
hehe( *´艸｀)
it’s becoming my own

Fluid is seeping

Even after overhaul, fluid is seeping
*right side only
even with new seals, it still seeps

the conclusion I reached
“there’s a void”

replaced the caliper and it improved
there was a void to begin with and it deteriorated over time
opened up with wet blasting
this is my first time seeing this
old bikes can have this kind of thing
I remember
receiving the baptism of a classic bike.

Once it runs pretty well
I start wanting to customize it a bit

I had already collected parts beforehand
so I combined them to create my own version
not for performance
“looks and sound“
perfect fit! (*´ω｀*)

I’m the type to source parts right away

you never know when something will be discontinued
it’s important to install when you want to
“time is finite”

by the way
I have no complaints about the stock brakes
“looks and the satisfaction of doing it”
that’s all (*´ω｀*)
bikes have an afterimage you see later
“lingering feeling”is also important

Oh… really?

• Foot placement is incredibly good
• Lightweight and nimble
• 550/50PS is no joke
• Used market prices are affordable
• Be careful, it’s a 25-year-old vehicle
• New parts are still readily available
• Custom parts are incredibly abundant
• Used parts are very plentiful
• Carb/no emissions is reassuring
• There’s some risk of theft

This might be a bike I end up keeping to the very end…

For air-cooled 4-cylinder fans, I’d like you to ride it at least once
this is just my personal opinion
“take it as reference”