2005...With the engine fully broken-in and tuned to
a razor's edge, we turned our attention to front-end upgrades. The
fork legs and disc brake setup from a fullsize Honda were adapted to
fit. Most disc brake conversions require the use of aftermarket
wheels, front and rear, adding hundreds of dollars to the final cost
and changing the look of the bike even further from original. The OE
wheel and hub combo are fairly versatile and just look "right"
on these bikes; retaining them also allows retention of the
original speedometer drive with minimal modifications. We
worked with a local machine shop and used this project to prototype
the pieces and required mods. A quick trip to a metal supplier, an
afternoon's fabrication & polishing turned a piece of scrap T6
6061 aircraft aluminum into our new adjustable headlight mounts. The
final pieces of this puzzle are the alloy upper and
lower fork trees; a stainless steel retaining nut was custom
made and we installed a tapered roller bearing headset as
well. Minor mods were required to mount the master cylinder.
The new fork shocks are a good match for the weight of the
bike, a bit better than stock K1-`79 and give a quiet,
well-controlled, slightly firmer, ride quality. The front
caliper is a twin-piston unit and the newfound stopping power is
fade free and nothing short of awesome. The bike can now be yanked
to a stop from 60mph with authority. Overenthusiastic
application of the front brake could easily put the rider
over the handlebars! So there you have it... a classic Honda
Minitrail from the early `70s, updated with a balance of modern
power, brakes, suspension, lighting and speedometer to
match. Best of all, the updates
were realized using genuine Honda parts,
without breaking the bank or losing the classic lines of the
original bike.
From this point we feel that the bike wants for very
little in the way of additional improvements. It is now a competent
and reliable road machine, able to handle 50-55mph traffic with
relative ease, even riding two-up; it seems just as
happy covering our favorite logging roads in the wilds of
Michigan's upper peninsula. And, of course, just as
importantly, is still easily transported in a hatchback car or
minivan. It's that combination of portability/diminuitive size,
2 passenger capability, on/off road competence, and OEM
reliability that set this machine apart from other bikes. We can't
think of another that's as versatile. Thus, there are only a
few very minor refinements planned ... but then
you never know!
A Bump In The
Road (Literally & figuratively)


June 6th, 2006
A perfect summer day, sunny & 85 degrees.
After the unusually cool weather of April and May, we were anxious
to get out and catch some sun & breeze. What better midpoint
than a tongue-in-cheek attraction... Hell, Michigan, on the one day
this century with a date of 6-6-06. This normally quiet, idyliic,
setting along the Hell Creek located amidst the Pinckney State
Recreation area was packed to the gills with a couple thousand
day-tourists, mostly bikers. The first 110 miles of our 120-mile
sojourn went along uneventfully, as planned... an hour and fifteen
minutes out, the same back with an hour's stopover in the middle.
Unfortunately, the return trip would provide a nasty surprise. About
10 miles from home, we hit an unexpectedly rough railroad crossing
at 50mph. This had happened many times before without incident, thus
what happened next was quite a surprise. A loud cracking noise was
heard and the bike suddenly felt loose. We quickly pulled off the
road in an attempt to figure out what had happened
and discovered nothing out of place. Heading back out onto the
road, the bike still felt odd, yet a second going-over revealed
nothing more than the first. It wasn't until we returned home that
we discovered what had happened; the RH upper shock mount had
snapped cleanly at the shoulder. Since the outer stud/nut was
intact, everything appeared to be intact & in place, held
together by the muffler mount. The Kitaco shocks were so stiff that
the LH shock alone was enough to allow the bike to be ridden with
only a vague sense that something was wrong. (The spring preload was
on the softest setting!). Giving the devil his due?
Hardly. Remember that RH shock mount was bent when we
received the frame. We had our doubts about its condition, even
after it was straightened. But, after survivng 4000+ miles, some of
which had been riding two-up over trails, with no signs of imminent
failure, we hadn't expected this.
Fortunately, nothing else was damaged. The
remaining mounts (frame & swingarm) were all perfectly straight,
even the single shock absorber was intact. The first thought
was to thread the outside of the remaining stub and machine an
adapter, similar in design to the stud/nut used to mount the muffler
to the shock mount, only larger and of stronger steel.
Unfortunately, the shock mount axle is not a standard size, nor is
it uniformly round. Thinning the center section would weaken
its structural strength. The original shock mount was
DOA.^(
Since this frame was solid, straight and free
of rust...not to mention titled, insured & registered, we
didn't want to scrap it. Sometimes when life
hands out a lemon, it really is possible to make lemonade (or,
perhaps more accurately, "chicken salad from...chickens**t"). Here
was an opportunity to overcome a problem that has spelled "the
end" for many a CT70 and make the bike better than new in the
process. We had to rescue our faithful workhorse from the
glue factory...and begin what would be its transformation into the
ultimate dual-purpose machine. You didn't really think we could
leave "well enough" alone did you? Our motto is " when somethng
fails, replace it with something better. While the bike was
completely torn down, to be rebuilt from scratch, we weren't
starting from scratch this time.


LEFT: Initially, it appeared
that we could simply use a fine-thread die to cut threads into the
outside of shock mount axle stub. Those traces of paint
& primer were a worriesome sign, but the
non-threaded area at the upper left meant that the mount axle
was not perfectly concentric. Since the threads that were cut
were marginal, at best, with minimal depth, this
repair was not viable and major surgery would be
required...shit!!! RIGHT: Since any
proper repair would involve welding, it was decided to replace the
original mount entirely. Being dedicated to ongoing
improvements ("if something breaks, replace it with something
better"), in this instance, that meant having a new center section
precision machined from steel twice the diameter of the
original, the use of grade 12.9 bolts the diameter of
the original center section, and adding bracing plates to the
outside of the originals. The weak point is now the bolt, which can
be easily replaced. Aside from not wanting to repeat this repair,
the viability of doing so is questionable. Plus, that
would mean stripping & painting...yet again (ugh). This is
why we shifted the breaking point from the mount itself to the
bolt. Realisitcally, the possibility of the bolts breaking is
remote. If one were really worried, it'd be easy enough to carry a
couple of spares and an Allen wrench. The
center section is as large as we could go without making wholesale
changes to the frame (more cutting, bracing & welding). Rockwell
testing showed that the bolts are far stronger than even the thick
center section of the OE mount.


This kind of frame surgery isn't
for the inexperienced, or the faint of heart. But it's the only way
to replace the shock mount axle. It's interesting to note that the
metal is about .1875" thick at this point. Honda was years
ahead of the rest in applying unibody technology to bike
design.


Left: New mount center section in place for
mock-up. No, we're not inventing the new CT70 dice game, those
are the spots where the new outer bracing plate will be
plug welded. As can be seen, the metal was quite thin at the bottom
of the frame sidewalls after removal of the factory shock mount.
While the most of the strength comes from the material above the
mount, it is always best to distribute loads over as large an area
as possible when dealing with this type of frame construction. The
principle is the same as installing a roll cage in a race car.
Below: After a quick trip through the
blast cabinet, the new .1875" thick sideplates were
plug welded to the originals and metalfinished. Note the added
material at the bottom.



On the road again...
Unless the seat is raised, the
repair is barely visible. Unfortunately, the paint
suffered third degree burns and some serious paintwork lies
ahead. Once refinished, the repair won't be noticeable at
all unless the seat is raised and there's no worry about
breaking another upper shock mount. In the unlikely even
it were to happen, the wheel would probably be damaged from the
severe impact required. Replacing the upper shock mount bolt would
be the easy part. This is our second skunkworks
project...the CT70 upper shock mount repair kit.
IMPORTANT NOTE: While we feel that the upper shock mounts are weak
points of the CT70 basic frame design, we don't believe that they
are exceptionally prone to breakage. The frames that we've received
with bent shock mounts have all shown evidence of abuse, such as
stunt jumping. As can be seen in the first photo of the shop bike,
it only had the RH shock when we got it. Considering the neglect
& parts cannibalization the bike had endured, it's not much of a
stretch to imagine some numbnuts riding it minus the LH shock. Weak
shocks can be even tougher on the bike's structure than overly stiff
shocks. They'll bottom-out easily and once that happens, there's a
solid mechanical link between the road and the frame. It's a bit
like hitting the shock mounts with a sledgehammer. Stock shocks are
pitifully weak and bottom-out easily under adult weight; a single
shock would be like no shock absorber at all. The cause of our
broken mount: microscopic cracks on the underside of the mounting
stud, at the shoulder point. Over time, these created a stress
riser, where the metal snapped after becoming
work-fatigued.
We replaced the noisy
& rock-hard Kitaco shocks with top-of-the-line,
high-pressure gas-filled, shocks with piggyback reservoirs, from our
our own line of high-quality shocks . The improvement in ride
quality is unbelievable, even when riding two-up. The damping
chracteristics are a quantum leap beyond the old Kitaco pogo sticks.
And unlike the Kitacos, they're quiet. The bike has seen about 500
miles with this setup in place, 150 of which was
done riding two-up (320lbs of combined passenger load) over
nearly every kind of road condition imaginable, including dirt
roads and railroad crossings. The range of spring preload adjustment
is more than adequate for anything we'll ever need without the
harshness of overly stiff springs. We'd guess that the bike could
carry as much as 350 lbs, but that's just an educated guess
based on our experience.
What's Old is New
Again... Rebirth of the Shop Bike
With the end of riding season
close at hand, we decided to move forward with the complete teardown
and refinishing. We have some big surprises in the works
and, paintwork aside, winter is the best time to tackle major
projects.




What was "good enough" when we started out years ago
just won't cut it anymore. Once a new finish is applied, you
quickly forget about the warts beneath its surface. After stripping
the frame back to bare metal, we repaired some "rediscovered" dents
using body lead instead of plastic filler as had been done last
time. We also smoothed-out the chain damage and rough welds on the
swingarm. This time around, the shop bike gets true candy ruby red
and the frame, though mostly stock in terms of metal finishing, will
have the crisp appearance of a freshly pressed $2000 suit.

The Shop Bike
- version 3.0
Over the past six years, we've
used and at times abused the shop bike. It's served as guinea pig,
lab rat and even crash test dummy for a number projects;
perhaps your engine was road-tested and/or broken-in fitted
into this bike's motor mounts.
This latest project began with a huge head start,
courtesy of our long-suffering machine. The tradition continues on
as, rising yet again, Phoenix-like, from it's own burnt wreckage,
"Old Reliable" comes back for the latest round of innovations,
with some great surprises along the way.
First order of business was a
complete repaint in true "Candy Ruby Red", the last paint job of the
2006 season. Previously we used DuPont Chroma red,
a "near candy". While a decent simulation of candy red
and very simple to apply, there's just no substitute for true
candy colors. Though it's only necesary to wait a couple
of weeks before applying decals and such, we wanted the luxury
of completing the bike slowly during the off-season, giving the
paint months to fully harden. Unfortunately, between multiple
engineering challenges, supplier and chrome plating delays plus
a heavier-than-expected springtime schedule, we were unable to
complete this project until late July. We should have known better
with a custom project; Murphy was an optimist!
We've never been afraid to
discard our own work in favor of something better. Thus,
we painted two headlight shells, a K0 and a 12V type, the
stock swingarm and chainguard, knowing full well that there would be
"spare parts" at the end of the build. The later-style headlight
shell is an inch larger in diameter, which makes for better lighting
with the Nice alternator and 4x OEM capacity battery we've fitted.
In the end, we used the larger headlight,
as expected. It is a tight fit, especially with the billet mounts
which we hand-fabbed. The chainguard and swingarm also ended-up in
the spare parts bin. We chose to retain the engine-mounted
chainguard, making the OEM unit redundant. Also changed, at the 11th
hour was the swingarm. While the stocker is a plenty stout piece,
likely tougher than our aftermarket alloy replacement, it's not
without its shortcomings. The rubber pivot bushings work well
enough, and we've seen few that have failed, but...they do bind
a little at the extremes and our biggest gripe is the fact that
there's no good way of preventing chain contact from chipping the
paint on the LH side. The chain adjusters also rip through the
paint at the axle flanges. Thus we jumped at the chance to test
out a new-design, triple-wall, aluminum swingarm with ball bearing
pivots. It comes standard with a nylon/delrin chain
pad which absorbs any chain contact and the chain tension adjusting
system doesn't chew-up the axle flanges. Losing some unsprung weight
didn't hurt anything either; there's been a noticeable improvement
in the rear suspension action. We also added a subframe brace for
added frame strength and rigidity.


The front end presented a number
of engineering challenges. First off, it was decided to stick with
the OEM Honda disc brake we've been using. This is the same
twin-piston caliper/220mm disc setup found on some larger (and much
faster) bikes such as the NSR - "if it ain't broke..." That left
only a few thousandths of "wiggle room"; brakes being
a high-precision item. We've also received a number
of requests for a setup that would allow fitment of
a 3.50" wheel as is possible at the the rear, which,
hitherto, has never been possible with off-the-shelf parts.
Further, when adding power to these bikes, it can be desireable
to extend the wheelbase and shift the weight bias forward. This
improves high-speed stability and makes the bike less
wheelstand-happy. There's also the issue of suspension action. The
K1-`79 front end is surprisingly good, for what it is, and can be
tuned somewhat through the addition of heavier springs and oil.
However, it still only has about 2.5 inches of travel. The
Honda Nice fork we had fitted previously was a little better
than stock and, of course, gave a greatly improved brake setup;
it still had less than 3 inches of excursion and the springs were a
tad on the soft side for offroad use. We knew going in that this
would be neither cheap nor simple. With the beleaguered greenback
falling to new lows against most major currencies, imported parts
(virtually everything on a Japanese bike), stainless steel, have all
taken major hits; aluminum, especially the high-strength alloys we
use, has become astronomically expensive. Furthermore, we used
USA talent to handle the design, engineering and CNC chores. This
time, it was absolutely a no-compromise approach with
everything subordinated to function. Extended-length swingarms
work well; added wheelbase smoothes the ride and adds straight-line
stability at speed. The trouble is...we don't like them
aesthetically. The CT70 frame is a stylistic element in its own
right and going more than +2cm on a swingarm makes the rear tire
appear disconnected from the rest of the bike. Extending the
wheelbase from the front end, is an approach we've not seen applied
to these bikes. Considering the difficulties involved, that's no
surprise. The effects are similar to fitting a longer-than-stock
swingarm, but the wheelbase extension can be less for the same
amount of effect, making it almost undetectable. Widening the
spacing not only allows a wider-than-stock wheel/tire combo, with
anything near stock width, the front wheel can be removed without
unbolting the front caliper. The fork legs we selected have almost
5.5" of total travel, real internal valving and readily available
preload adjusters. They also seem to have variable rate springs, not
an advantage from what we were told going in. Thus, custom springs
and valving were planned. We did consider fitting an OEM CT70
hub, however, they aren't as straight & true as we'd like for a
top-of-the-line front end. We normally have the lateral runout
corrected on a lathe when machining them for disc brake conversion,
but nothing can be done for radial runout and stock speedos can
sometimes leave a bit to be desired. Thus we went with billet disc
brake hubs and G-Craft CT70 wheel stars to retain the stock lines
with perfectly true-running wheels.


Off-the-shelf headlight mounts
are available and would have been a lot easier. With as much
tweakage invested in a project as there is in this one, you
had to know we couldn't leave well enough alone. We
fabbed a simpler version of the billet mounts used on the
custom special; they complimented the polished trees and aluminum
swingarm. We also fabbed a custom footrest unit, mounting the
footpegs higher than original for added ground clearance. This is a
benefit both on road, where peg-scraping leans can be hazardous in
tight cornering and for offroading, too. A custom battery carrier
was fabbed as well. The new, larger capacity 12v sealed batteries
available are physically larger than anything used in these bikes
"back in the day", but they do fit in the stock location with a
wider-than-stock carrier and careful placement. That's a serious
consideration for a clean underseat area and to provide room to
mount the voltage regulator or CDI. When we first built the shop
bike, we had no source for OEM Dax decals; we are now able
to source a pair that were the same as the 35 year old OEM JDM set
the bike came with. The only difference is that these have yellow
lettering instead of orange. We also decided to move the horn to the
RH side using an engine guard bolt rather than drilling and tapping
a hole into the lower tree. The low-mount, late model ST70 fender
was retained, though the mounts proved cumbersome due to the
relatively heavy fender. The high-mount CT70 front could have easily
been fitted and does look better. Remember, this is an exercise in
pure functionality. Things have to look good, but only in ways that
do not detract from function. The low mount fender does a far better
job of keeping crap off the engine and lower surfaces of the bike.
Dirt/gravrel roads in this part of the world are treated with
calcium chloride to control dust. Calcium chloride is, in reality,
salt and is murder on steel, aluminum and chrome.
With a mudflap fitted for offroading, the bike should remain nearly
spatter-free, with zero reaching the engine itself.


The last few details were just
that, finsihing details. Some of them were a bit over-the-top (we've
become polished aluminum addicts), but, if you consider the reality
of them, they're mostly more practical than intuition would
indicate. The RH engine case was polished. We grew tired of the
rough-ish black factory powdercoat and it was pretty well scarred
from multiple engine R&Rs. Fact is, it doesn't take much to
maintain polished aluminum. Engine parts get hot and that slows
oxidation. Two or three sessions a year with Mothers mag &
aluminum polish or Neverdull and paste wax should do it and the
shiny surface won't chip off. We added a red-anodized outer clutch
cover (purely decorative) that looks pretty cool with the
polished cover peaking through from below. The red color goes well
with the bike and the rising sun motif seems fitting for a bike of
Japanese origin. We also polished the stator cover plugs for the
flywheel while we were at it. Pretty much everything else was reused
as-is. The rear shocks were fine, as were the rack, seat, tank &
bracket, oil cooler, carb, handlebar assembly, rear fender and tail
light assembly. Even the chain and sprockets, after 4500
miles, were like-new. We ran the chain thtough the parts
washer, then lubed it with molten paraffin. We did replace our
5-year-old Trailwings. With roughly 5000 miles of mostly
road riding, they were a bit "tired". Amazingly, the rear brake
setup was still like new. The clearcoat has kept the polished
aluminum backing plate looking the same as it did years ago and
there's less than 25% wear on the brake shoes. It was still amazing
how much work was required to free the rear tire from the split rim.
Even without rust, it bonded quite convincingly to the rim. The
wheel paint is still like new. The old air filter was
swapped-out in favor of a new-type UNI airfilter. It's an ugly
thing, but especially well-suited for dusty conditions. The capper
was the prototype of our upcoming "super stealth" exhuast. The aim
was to see how quiet we could make the exhaust at speed, while
retaining a nice, healthy-but-mellow thump at idle without a power
decrease or an exhuast note with the dreaded "wet fart"
character.
The finishing
touches...
The bike went together with lots
of surprises along the way. Funny how seemingly minor changes result
in cascading alterations, but that's life. The front fender
mountings took some .625" 6061 aluminum bracing to locate that heavy
front fender solidly and both tire and fork clearance are incredibly
tight. All stainless hardware was used instead of the original
bits. The bike is now so far removed from stock, that there was no
point in retaining the stock plated steel pieces. Another longtime
provider of show-quality chrome plating passed away during the build
process. We'll miss him and there's not likely to be anyone stepping
into his shoes. (Hey, we said there were numerous complications this
year) This prompted our decision to change the design of
the subframe brace and likely discontinuation one version.
There were a couple of machining issues and way more fabrication to
deal with than anticipated along the way. It took two full
days of metal fab & polishing. Just about the time we resigned
ourselves to dragging every single detail of this build, kicking
& screaming to completion, it was ready to roll. That's where
things changed in a big way...for the better.


Having been out-of-the-saddle
for 10 months we figured that it would take lots of road miles
to get everything tweaked and even more time to cover enough miles
to figure out how much difference our changes had made. This was one
time when we were thrilled to be wrong. The bike fired
on the first kick and ten minutes later was rolling down the
street. It took less than 500 feet to tell the difference, no
exaggeration. The ride is Lexus-like, plush yet controlled. The bike
is smooth as silk for its size and the suspension soaks up
everything the pitiful roads around here have to offer. We now have
to be careful over railroad crossings, as they're hardly felt.
Previously, the suspension would bottom-out unless we slowed
considerably. With the preload adjustment exactly in the middle, the
bike only uses about half of its fork travel most of the time, even
with 320lbs or rider & passenger aboard. That's about the full
range of the stock fork. The last 2-1/2 inches are still there, just
waiting for something outrageous. We hope to never hit anything that
hard, it'd be one helluva pothole!! The difference in ride quality
is accompanied by improved weight distribution and stability, as
expected. Even with the front end ride height set about .500" higher
than stock and our rear shocks about .750" shorter than the first
aftermarket pair (making them about the same as OEM stock), turn-in
is noticeably better than ever. Even the erstwhile Kitaco
350mm units weren't as good, the one area in which they excelled.
Front end height is infinitley adjustable, we sneaked-in the extra
height for added ground clearance...and got away with it. The bike
is now so smooth and stable that it just begs to be ridden more
miles. Spousal approval is now "two thumbs-up". First day out saw
135 miles and nobody was saddle fatigued, neither rider nor
passenger. It only took 4 days to cover 567 miles. If there's a
downside, it's that all of this newfound comfort & stability has
decreased the sensation of speed; the super stealth
exhaust adds to this effect. We hadn't considered this
possibility. Whether it's good or bad is up to the individual rider.
We are, as yet, undecided. The suspension is so good that
we'd never go back...ever. However, a little bit of exhaust snarl
might be more satisfying, at least part of the time. For that reason
we are, for the moment, considering an adjustable baffle for this
newest exhaust.

Notes on the Super Stealth
exhaust...
Our original Stealth Exhaust system has been a
huge hit. Stock appearance, free flow and a note that's "just right"
is a tough act to follow. There are, however, certain
circumstances and individual preferences to consider. On long rides
and in wilderness areas, even a moderate performance sound can be
distracting. According to standard wisdom, sound equals power. We
fully expected to lose a couple mph of top speed. That's no big deal
for a road cruiser. Top speed is limited by gearing as much as
anything, so our top speed won't go much beyond 65mph even downhill
with a tailwind; the engine will run out of revs. The goal was a
mellow tone at idle and under power and quiet part-throttle
cruising. Putting years of experience and theory into practice, we
have developed a clean-slate baffling system for this skunkworks
project. At idle, the note is deeper, with more heft, yet 3-5db
quieter. At WOT, that character changes a bit. At lower revs, below
6500rpm, induction noise is equal too, or exceeds, exhaust noise.
Above 7000rpm, the exhaust note overshadows induction sounds with
the same mellow roundness as at idle. At part-throttle cruising, you
move along almost silently along flat roads. Using a dead-accurate
speedometer in back-to-back testing, the results held some
surprises. The bike seems a tiny bit slower with the quiet
muffler. In reality, it's faster. Top speed testing would have been
pointless. We're gearing-limited and there's way too much traffic
locally to find out the absolute limits. However, there are some
decent hills in the immediate area and hill climbing ability is very
relevant; that's an indication of real world roadworthiness. We also
have a few tightly defined "test tracks" short stretches of road
where you must brake at the same place, or earlier, to avoid
disaster (so no "cheating"). Where we saw 53-57mph with the original
exhaust, we saw 56-61mph with the super stealth. All tests were
repeated with multiple "ride it like you stole it" blasts all
carried out within 90 minutes over exactly the same locations.
Theory worked as applied. The performacne gains are
subtle going by seat-of-the-pants feel. The
new exhaust is labor-intensive to produce, so early adopters
may snag a bargain.


There were three issues
left to resolve...appropriate sidebages, final configuration of the
front fender mounts and the speedometer. The fender mounts, as they
are, didn't cover the exposed inner fork legs and were on the
ugly side. We thought about replacing them with square billet,
but lack of clearance limited structural strenght.
High-mount fenders are a non-issue; simply drilling and
tapping three holes and making a spacer... and it's done. We fabbed
a pair of deflectors/guards from 6061 and added them to the existing
mounts. The speedometer was more of a challenge. There is
no aftermarket drive that is correctly calibrated an OEM Honda
speedometer and 4.00 x 10 tires. We found this out thr hard way. The
speed readings feel about right but are actually slow. Ego aside,
that's not a good thing. At first we wondered why the bike was so
sluggish at speed, that is, until we noticed that traffic had become
uncharateristically slow on every local road. In our
locale, speed limits are taken as suggested minimums.
Luckily, we checked the speed with radar and a pace vehicle
without any speeding tickets. The solution was a hard choice.
An OEM hub conversion just didin't fit with this project. A shorter
tire, such as a road tire used on a 12V ST70 would probably lessen
the error considerably. That's not viable on a true dual-purpose
bike. A second set of rims & tires doesn't really fit the "get
on & ride" goal either. As the Trailwings wear down, speed
readouts will gradually gain about 5-6%, who wants to wait until the
tires are ready for replacement? The only other
choice was a user-programable electronic unit. We selected a
unit that we could fit inside the speedo/headlight bucket.
Not our first choice, but it preserved the stock-ish lines of
the bike, is dead-on accurate and we gained trip meter and
timer functions. We had planned on using an OEM 60mph Honda
speedo with integral trip meter. Oh well, can't have everything.
That's it, the bike is now done. There's nothing else left to
upgrade or changeout.

Conclusion
It's taken a lot of time,
experimentation and resources but we ultimately achieved our
longtime goals:
-
Adequate power to keep pace
with traffic, no less than 45-50 mph on a 10% grade while riding
two-up and 50-55mph steady-state cruising on relatively flat
roads.
-
OEM Honda
reliability
-
Smooth-shifting transmission
and strong clutch.
-
12 volt electrics with
enough output for decent lighting.
-
Enough braking power to yank
the bike down from 60mph at the limits of tire adhesion even with
300lbs of rider & passenger aboard.
-
Competent, adjustable, no
excuses, suspension for comfortable riding with the
ability to transition from road riding to
offroading and back seamlessly.
-
Retention of the essence of
the original bike: folding bars, mostly stock lines and ease of
transport in a car/small van/SUV.
That's a tall order and from the
outset, many have told us it wasn't possible; yet, in the
end, we actually succeeded beyond our own high expectations,
something that has rarely happens. We feel that the shop bike
represents the ultimate dual-purpose-cruiser CT70. It has
enough power to competently move along at any legal speed at which
it can be ridden, even with up to 320lbs of combined rider/passenger
weight aboard, with brakes and suspension to match. While the
low-mounted front fender isn't our first choice in terms of
aesthetics, it's clearly superior functionally. In addition to being
much more effective at keeping things clean, the added airflow
through the oil cooler is a welcome improvement. At speed, the
airflow coming off the cooler feels like a car heater set to "max".
We gave the bike its "trial by fire" on a 95-degree day. Riding
two-up and at sustained speeds in excess of 50-55mph uphill and into
strong headwinds, the oil temp topped out at 107C. That was after 25
miles, with roughly 10 miles of wide open throttle. On the return
trip, oil temperature never exceeded 95C. 700 miles later, we backed
this up with a second test that completed the circle. With our
Copper Harbor trip out of reach for yet another year,^( we took a
120-mile day trip ...where else?...straight to Hell (MI). That's
where this last stage of upgrades began and where our vacation
travel plans went (wry chuckle). The bike, at least, came back
intact. Ambient air temps were in the high 90s,
with strong, gusty, headwinds on the outbound leg of the ride.
With 335lbs of rider, passenger & gear aboard, at least 40 miles
was covered at, or near, wide open throttle. Again, oil temp
topped-out at 111C (about 230F) demonstrating not only the toughness
of the Honda motor and perfect state of tune, but the sizing &
placement of the oil cooler as well. This time, we saw peak readings
of 103C on the return trip, on one prolonged uphill section. Some of
the grades encountered, in combination with the strong headwinds
limited top speed to 50mph. That's as hard as the bike can be
pushed; with 9,000 trouble-free miles under its belt, we
consider the Honda Nice engine virtually bulletproof. The stock
lower end has proven reliable with up to 160cc over the past six
years with nothing more than the addition of heavy-duty clutch
springs. In stock form, the engine is pretty well unstressed even at
wide open throttle; that's really at the heart of the
reliability/durability issue. The bike has the kind of "set it &
forget it" reliability and OEM-like balance we always
wanted. The ride is more akin to that of a full sized
125cc bike. We chose to forego adding extra power or road tires
in favor of a ride-it-anywhere, run-forever setup. The ride is
amazingly plush, requiring no compromises. Slap-on a pair of
road tires and the bike would be ready for some very spirited
workouts through the twisties; it'd also gain a few mph on the top
end. Add some more power and a steering damper and you'd have the
upcoming silver bullet. That's amazing versatility...going
from relatively tame to insane with a change of tires, engine and
addition of one component. What's more surprising is that we're
talking about a 1960s-era design, old enough to be exempt from most
restrictive regulations, that's still not dated after four decades.
A classic that we just made even better, realizing its full
potential.
There is one last
installment planned for this series, appropriate sidebadges.
Those may be another skunkworks item. With the number of Nice
conversions now out there, it's time to offer these for that final
grace note.
This bike has taken a lot
of torture and, we feel, has earned respect. We're going to put
LOTS of miles on her and enjoy them all. We'll see how long we can
maintain the current condition with proper maintenance. That's it,
we have our "ultimate CT70 the way Honda should have built it" and
it's a great little "vest pocket" touring machine. Any further
changes would be guilding the lily. That doesn't mean that there are
no other directions to pursue, we'll just do that with other
bike projects. The Shop Bike has reached it's ultimate
conclusion. We know only too well that nothing stays the same.
However, for the intents and purposes of this, specific,
project a new state-of-the-art has been acheived.
Thanks for following along. We
sincerely hope that you've enjoyed this saga and that the CT70
community, in general, will benefit from our developments. We'll
happily supply virtually anything you've seen here.
