Honda SL90K K1 #01
Candy Emerald Green / White
Completed January 04, 2012
This is a very unique bike
here in the states. This is a 1971 Honda SL90K
Japanese Domestic, which simply means that it was a
non-export model sold in Japan. Apparently they needed
a model with less cc's or less horsepower to meet
regulations and they built this off of the SL100 platform.
I only know of a very few of these that exist these days and
this one only showed 41 kilometers on the odometer when I
got it. It was hard to believe the mileage until we
disassembled the engine and found virtually no wear on the
cylinder / piston. It did have a completed wasted cam
journal and that may have been its' demise back in the day
and that may have been why it was preserved.
Unique items include; black
frame instead of the traditional silver for the Honda
Motosport bikes, center stand, buddy pegs, upswept muffler,
smaller carburetor, different air intake boot to mate to
carburetor, crossbar handlebars, addition of a tachometer,
uses an SL125 headlight bucket to accept the two cables for
the instruments, turn signals, unique LH switch assembly to
accommodate the turn signal switch, helmet holder, SL90 side
cover badges, seat cover much like an SL100 K0, but with a
buddy strap, buddy peg perches welded to swingarm, unique
routing of the coil wire, license bracket assembly made to
hold Japanese license plate, non adjustable headlight (side
to side), front headlight ears made to accept turn signals,
wiring harness made to accommodate turn signals, bridge
rectifier and 6v turn signal flasher, reflective tape stripe
on front fender and all decals in Japanese writing.
Brochure pages below.
With the rarity of this bike I
thought it deserved some professional pictures and those are
next, followed by my normal ones by the pool.
My 'normal' pictures follow here......................
Unique reflective tape stripe
on front fender.
Non U.S. non-adjustable
headlamp & front turn signals.
Headlight ears made to
accommodate the front turn signals.
The SL90K has a much smaller
bore carburetor than the U.S. spec 100's
Badges that I had reproduced.
Two-up saddle with grab strap.
Upswept muffler to clear the
Buddy peg mounts welded to the
Rear turn signals mounted to
the upper shock bolts.
Non U.S. spec taillight lens
with orange reflectors on the sides.
Unique license bracket with
different spacing for license plate holes.
This is how it bolts to the
Speedometer reading in km/h.
Unique switch with turn signal
provision but the lever perch is separate. Honda CL's
and CB's had turn signals, but the lever perch's were built
into the switch and they used different levers.
Bike came with a center stand
where the U.S. spec bikes did not.
Another shot of the license
Bike came with a helmet holder
where U.S. spec bikes did not. Reproduced helmet
holder sticker in Japanese writing.
Tire pressure warning sticker
reproduced in Japanese writing.
Reproduced battery caution
label in Japanese.
Good shot of the center stand
Another shot of the smaller
carburetor. Presumably the smaller bore altered the
H.P. for different licensing restrictions.
Grab strap mounting hardware.
The headlight bucket on this
model had to be like the one for an SL125 with the cutouts
for the two instrument cables.
reproduced with Japanese writing.
Close up shot of the
reflective tape on front fender.
Assembly & Original Pictures
Day 1 Assembly started December 26
Even this Air Cleaner to Carb
boot is unique as it has to neck down to the smaller
Day 2 Assembly started December 27
2011 - Up on 2 wheels.
Day 3 - Going together with
I'm using a set of original
Honda levers with the clear coat still intact. Been
saving these for a long while for a worthwhile project.
Special derby cover with
cutout for checking timing without getting oil all over the
IV Fuel bottle hooked up and
engine is ready
This is the unique license
bracket with a much narrower spread for the plate than the
Tire Pressure Decal -
Reproduced with Japanese characters
Battery overflow hose routing
- In Japanese
Helmet holder - In Japanese
Reflective tape on the leading
edge of the front fender. Picture of original laying
Two up seat with grab strap.
Center Stand in place
This is the unique reflective stripe on
the leading edge of the front fender
End of Day 3
Side Cover Badges (Finally
arrived - Thanks to my reproduction guy)
Original Pictures Follow:
looking forward to starting....and finishing this project.
This is a Japanese Domestic SL90K. Apparently there
was a cc limit for certain ages in Japan and they made a
90cc version of the U.S. spec SL100. This bike is not
to be confused with the U.S. SL90 made in 1969 that was the
first to be introduced Honda Motosport lineup.
Completely different bikes. The SL90K's had a
centerstand, turnsignals, reflective tape on the front
fender, upswept exhaust to make room for the rear buddy pegs
and a seat that resembled the SL100 K0, but with a buddy
strap. As you can see, this model has differences from
the SL90K K0 model in that this one has a black frame,
crossbar handlebars and the addition of a tachomter along
with the speedometer. You will also notice that all
the decals are in Japanese writing throughout the bike.
The odometer on this bike shows 41KM. Not sure how it
got into the shape it is in, but will see when it gets torn
This is how I found the bike
with the ratty seat etc, but it does run well. The
strange part is that the speedometer shows only 40
Kilometers, but parts of the bike sure don't represent that
low number......however, look at the front tire which
appears to be original. The mudflaps on the bike are
not factory original, but the little reflective tape on the
leading edge of the front fender is.
Here you see the crossbar
handlebars and tachometer which the U.S. Spec SL100 did not
Here is one of the unique
stickers with Japanese writing. This is located up
near the steering neck.
Here is a good shot of the
upswept muffler which allows for the passenger pegs.
The mounts for the passenger pegs are welded to the swingarm.
Here is a shot at the original
tire which also shows very minimal wear, but
realistically.......maybe more than 40 kilcks.
I'm not 100% sure, but many of
the Japanese scooters I've seen had the yellow reflectors
built into the taillight like this one and this lens is in
really nice shape.
The license bracket portion of
the taillight assembly is bolted together instead of being
welded like the U.S. counterparts. The distance
between the license plate holes is also different.
The seat has the grab strap
and you can see the mount for the rear turnsignals which are
missing from this bike.
The seat is styled after the
SL100 K0 with different pattern from the SL100 K1.
Unique to this bike is the
turn signal switch incorporated into the horn button
Notice the absence of the
on/off/on switch on the RH switch making both this and the
LH switches unique to the Japanese Domestic machines.
Here is that speedometer that
I've been talking about. "W" Stands for Winkers.
Bike perched on the
The rear sprocket on this bike
looks larger than any I've ever encountered which also leads
to some of the mystery as to why someone would change that
out, add the mudflaps, remove the turn signals and then only
ride a few kilometers.
I am currently having these
Here is a good shot of where
the reflective tape is on the front fender.
This is the non U.S. spec
headlight or "bugeye" which is non adjustable from left to
right as was necessary for the U.S. version of the SL100.
The headlight ears are cut to
accommodate the turnsignals.
Turn signal mount on the LH
The engine number is on a
sticker instead of being engraved in the engine cover.
Chainguard decal showing the
tire pressure for 1 up and 2 up riding.
Welded on rear footpegs
Helmet Holder decal.
Footpeg mount welded to the
The license plate bracket is a
two piece item. Looks like they took the U.S. spec
model and just chopped it off. The distance between
the holes for the license plate is different for the
Battery hose routing decal.
Placement of the Battery hose
Placement of the flasher for
the signals. Glad that this was on the bike since the
signals were missing.
Much different wiring than the
U.S. spec model. Assuming that is a different version
of a selenium rectifier.
Probably not the original tool
kit..............but a nice one.
Lots of parts to collect and
will get started on this one. Documented that they
came in Candy Emerald Green, Candy Ruby Red and Candy
DISASSEMBLY COMPLETE -