You
really never know what you are getting at motorcycle auctions unless
there are details specific to the history and current running state
in the auction highlights. Usually, there is nothing like that
available to prospective buyers/bidders. You get a couple of photos
and a couple of lines about what it is and from what “collection”
that it came from and that’s about all.
Case
in point: I bid and won a 1967 CB125SS bike at a recent Mecum
auction, which carried scant information about what it was and where
it came from. These bikes appeared to be solely Japanese Domestic
Models and few have survived after 53 years, much less having been
lovingly restored in the Mid-West a few years back. These bikes
originally came in various metallic Candy colors, rather than Honda’s
usual black/white/red/blue options, that were the mainstay of the
color palette of the early 1960s. This one was painted a traditional
Scarlet Red, the color that you would have seen on a CB77 Super Hawk
or S90 or CB160 back then. So, “points off” for non-original
paint color. That said, it looks wonderful in this color, mimicking a
CB160 in size and overall configuration. 1967 was a cut-off period
for the 160s and newly designed CB175K0 and this CB125SS were
transition models between the old “toaster tank” models and the
chrome-fendered two-tone paint schemes commonly seen on 1968-on CB175
and CB350 twins. Despite numerous visual similarities to the earlier CB125-160 models, the only parts in common were the knee pads and
rear mudflap/bracket.
I
brought the bike back to San Diego in my Tacoma truck after the
auction and set about to see what it would take to get it running, as
obviously, it hadn’t run for a while. The battery was flat and
wouldn’t take a charge and the fuel system needed some freshening
up as well. This is a rare electric-start model, a feature which
isn’t even shown in the period parts manuals. With fresh fuel and a
new battery, the bike did fire up, sounding a bit loud, as the
muffler system consisted of cut-off stock header pipes and a set of
aftermarket Thailand-made slip-on mufflers. Initial test runs seemed
to indicate a lot more power than recent SS125A and CL125A machines
which had come my way in the past few years.
The
shifting, however, was erratic and it seemed to skip gears and
couldn’t find neutral easily. Off came the clutch cover to see what
was going on and it was discovered that the shift drum detent arm was
off to the side of the shift drum stopper plate instead of riding up
on top of the notched plate. This is a very rare occurrence in my
experience, but I bent the roller arm just a bit in order to help it
maintain its correct location. The clutch outer plate, which has 4
pockets for the clutch springs had a big crack at the bottom of one
pocket and a large chunk missing from one of the other ones. This,
too, is something that is nearly unexplained and never seen
previously in my 50 years of wrangling vintage Hondas. A quick trip
to eBay yielded a used clutch assembly with a good pressure plate. I
buttoned the whole thing up and tried it again. Low-speed trips
around the neighborhood seemed to indicate that the problems had been
solved successfully.
Performance-wise,
the engine sounded quiet and didn’t seem to smoke out of the tailpipes, but when the compression was checked, the left side was 115
and the right side was 155! I found a somewhat tight intake valve on
the left side, so loosened it up to the .002” spec and tried it
again. Compression went up to about 130 and that’s all it would do.
Slightly low compression is often an indication of a broken ring,
scored cylinder walls, unseated rings or a mildly leaking valve.
Somehow,
the bottom engine case boss, which anchors the stock mufflers, had a
big chunk missing from the engine casting. When I finally tracked
down OEM mufflers, the middle brackets, which are supposed to anchor
to the engine case really didn’t line up to allow bolts to secure
the muffler to the engine. There is a rear muffler bracket, which
attaches to the frame and it holds the mufflers securely without the
middle one being present. But, the combination of that fault, low
compression readings and still erratic shifting when the engine was
hot lead me to decide to just remove the engine and remedy everything
that was going on with it. There are only 4 bolts holding the engine
into the chassis, so after the mufflers are removed and a few wires
and hoses disconnected, it drops down onto a small hydraulic jack and
off it goes to the workbench.
The
cylinder head was removed and valves tested for leakage by shooting
some spray brake cleaner down the ports when the valves were closed.
Nothing leaked there, so the next stop was the cylinder block. Once
the cylinders removed from the engine crankcase, the cylinder bores
had notable pockmarks along portions of the cylinder walls like tiny
termites had been gnawing at the top of the bores. The pistons and
rings were determined to be on standard bore and use of a hone
revealed some light ridging at the top of the bores. Ring gaps were
off at the wide end of the scale, as well. So, despite fairly tight
piston and ring sets, the left side was losing compression when the
rings skated over the dimples in the cylinder bore. Time for new
oversized pistons and a rebore!
The
engine had been assembled with a LOT of 3-Bond or similar liquid
sealer, so every gasket surface was coated with the sealant and stuck
together far more than usually found. With the clutch and oil pump
removed and the stator/ignition components pulled off the left side,
the engine cases could be split for inspection and replacement of the
lower case. In removing the top shift drum anchor bolt, it was noted
that the shift drum collar/roller was NOT present. I have run into
this situation with a CB92 engine and the whole shift drum assembly
was floating back and forth, selecting (or not) gears at random. One
tiny roller makes all the difference in the performance of the
transmission and that is what caused the detent roller to move over
and drop down!
When
I was studying the shift drum detent roller problem, I searched for
what would normally be a related part on the later SS125A and CL125A
models, which were sold in the US. The detent roller for those models
was easily twice the diameter of the one in my engine. There really
isn’t room inside the engine case to fit a large detent roller,
unless other parts were also changed. Checking the two different
parts and part numbers, I discovered that the shift drum detent
roller was engaging a smaller and reconfigured shift drum stopper
plate. Back to the same eBay seller for a whole used shift drum and
detent roller in order to see if the later parts could be
retrofitted into the 1967 engine case.
The
parts arrived quickly from Oregon and I set about to see if the next
generation parts would indeed fit into the earlier engine cases,
which seemed virtually identical. The used eBay parts included the
entire shift selection components, including shift drum, detent
roller, guide pin with a spring and detent plunger and both shift
forks. Everything was different than what was in my bike and
fortunately, all the used upgrade parts fit into the CB engine cases
perfectly. I reassembled the bottom end and sent the cylinders out to
be rebored to .50 oversize. I found a whole piston, pin, ring, clips
setup on eBay for $95, so with another $80 to be spent on cylinder
boring, the engine will be nice and tight and ready for service.
Old vs. new detent rollers
In
keeping with rebuilding any old Honda engine, I spent more than one-hour scraping old gaskets and sealer material from the top-end
components. Plan on some similar time to be spent on whatever engine
you might be working on in the future. The OEM gaskets were made of
asbestos and bond to aluminum in an unimaginable way over a 20-50
year period. This engine has been refreshed previously, but the
builder appears to have used some aftermarket gasket kits. He also
had used a liquid sealer on the head gasket, which adhered to the outer
surfaces. When the head was removed the head gasket delaminated and
there were signs of rust or corrosion that was embedded into the head
gasket layers. Honda always cautioned about using non-OEM gaskets in
their engines, even back in the 1960s, so this was proof-positive of
their warnings.
The last remaining “issue” for the bike is that the front brake is
really “grabby” when applied, especially at low speeds. I had the
front wheel off previously looking for signs of rust or other
corrosion that might make the brakes extra touchy, but not much was
evident. It is a good-sized twin-leading shoe brake, used on the
CB175s, which have 50% more power than the 125 and are capable of
nearly 80 mph. I scrubbed the drum with a Scotchbrite pad and took a
file to the brake shoe material, smoothing the high spots and
roughing up the glazed lining faces. The DLS brakes have a connecting
rod that runs between the primary and secondary shoes. I loosened the
locking nut and set the shoes so they would both be contacting the
drum at the same time. It appeared that the secondary shoe was
hitting early from the way it was adjusted.
Once
the cylinders were ready, I was able to finish up the reassembly of
the engine and bolt it back up into the chassis. It fired up quickly but still seems a bit fussy at part throttle, just off idle.
Compression readings are now 150-155psi now and there are no leaks at
gaskets or seals, despite no using any liquid sealer, other than for
the engine case halves. Honda didn’t build engines with sealers on
the gasket surfaces and neither should you…
Bill
“MrHonda” Silver
04-20
1967 Honda CB125SS
