With the electrical system
set-up and the bike semi-mobile in part 2, this section
will focus on closing in the gear-box and sealing it up for oil, and replacing
the light weight motor mount.
The side plate needed to replace
the clutch housing and the motor mount are cut from this sheet of stainless
steel, thickness approx 0.080".
As compared to the 0.045"
thin mild steel that made-up the original motor mount. The mount developed a
slight tear and eventually broke where it was screwed to the gear-box.
Motor mount being bent into
shape.
A 1/2" hole was drilled
into the hump at the back of the gear-box that was originally housing the
Kick-Start assembly.
To keep life simple, a rubber
stopper is used to seal the hole quite securely.
The SS plate is drilled and
shaped to a good fit over the opening.
The silver duct tape forms the
guide for the 1st of several layers of fiber glass that will be applied to
close-in the front of the gear-box where the 2-stoke engine was previously
located.
The entire area that will be
sealed had to be cleaned, sanded and finally washed with alcohol to completely
remove any oil or grease that would have kept the resin from adhering to the
casing.
Between layers of glass &
resin being applied, a simple template was traced onto a section of automotive
inner-tube.
This was very easy to cut out
and punch the numerous holes into.
The resin & glass section is
completed, as is the rubber membrane/gasket.
Don't get confused the images
are slightly out of sequence...
Two nuts w/clips were imbedded
into the resin mid way through the process. This is why it appears so thick in
the image above.
This is a close-up of the
threads printed right into the resin and the tops of the clips encapsulated.
The inside surface of the SS
Plate was coated with a light coat of grease. So were the screws that threaded
the resin and held the nuts in position during the lay-up stage.
If you forget to grease the
screws, the odds are good that the whole section will have to be busted out.
A last test fitting before
installing the rubber gasket.
The motor mount is slowly taking
shape as well, after some minor cuts, bends, a few welds and it is ready for
setting up on the gear-box.
On the left below the
motor/mount is set with an adjustable brace fabricated from a short length of
1/8" steel strap. With a short pry-bar the chain tension is set by lifting
the rear of the mount assembly and the bolt is tightened with a new lock washer.
Above on the right the gear-box
gets approx 500ml of oil which brings it's level just to the input shaft being
driven by the motor.
The oil works it's way out along
the shaft, and slings-out directly on to the drive chain. An unintended feature,
but one that I'm pleased with. After 15 minutes of run-time in the tub over an
hour period no leaks are visible beyond the line of oil being thrown by the
chain drive.
The motor was being powered
directly by a 12V battery while it was being filled with oil, at about the 350
to 400ml point the gear-box started to quiet down noticeably, though the motor's
no-load RPM sounded like it had dropped as well.
At some point I opted to seal
the bare steel and welds just to keep any rust from forming.
The previous runs in the
snow left everything wet and in need of drying off.
This is one of the rare
exceptions to the rule "Rider her hard, and put her away wet..."
There is a slim possibility that
the bike will be completely torn-down yet again, if so the entire frame will be
the same color, and not necessarily this shade of blue.
The motor/gear-box assembly is
reinstalled into the frame below, the only hassle is re-aligning the swing-arm
pivot w/ bearings and seals between the frame mounts and the gear-box.
To the right is a second brace
that keeps the motor mount from twisting, this support was a not as straight
forward as the drive side because the mount juts out 3/4" from the gear-box
casing. This support is also slotted to aid in tensioning the drive chain.
The bike ran for 2 hrs non-stop
at 1/4 throttle to see if the drive chain retained it's tension, and if any
leaks would develop... None!
The Suzuk-E is recharging in
anticipation of a quick run to finally gather the GPS data required to benchmark
the motor's stock "Loaded RPM" through the gears on level ground.
While waiting for the charge
cycle to complete, the GPS was strapped on and a cheap Digi-Cam was taped down
to capture the ride.
I had a great ride covering
about 4 Km round trip, half on gravel and half on paved road. (this is the
footage that made it into the video).
But I forgot to initialize the
GPS to log the run... A week of snow and other demands kept the bike the shop.
Over the course of the week I
started to concentrate on the Video for this page, but quickly found that a
session of shooting out in the unheated shop killed the VHS camera, so I was
left with little to no usable clips...
Since the VHS cameras owed me
nothing given their vintage, I researched the market for a true solid state
camera that had comparable optics to the old VHS cameras, but with a more
reliable video storage methodology... Ultimately I settled on a Canon FS10 which
didn't quite fit my budget, but as always I was able to rationalize the capital
cost for the greater good of theworkshop.ca
So alongside of learning how to
get similar utility from the micro-sized Canon compared to the Brute VHS units,
several of the sequences were re-filmed, and I watched the weather for a break
that would allow for another run, but with the GPS Logging...
During this interlude, I opted
to reset the timing yet again on the motor, but this time with the load of the
transmission in 6th gear and the rear wheel. At full throttle the current draw
on the negative lead of the motor is approx 6.5Amps (read on an analog meter).
This translates into an effective no-load power usage of approx 340watts (the
batteries were fully charged at 53V).
I found this to be a bit of an
eye-opener as more than a 1/4th of the motor's total output is being invested
into mobilizing the drive train before the bike even moves a centimeter. This
can be thought of as energetic overhead. The motor RPM was also verified to have
dropped between 3,600 to 3,800 RPM as well, since the gear-box has been filled
with oil.
The graph above is of the Suzuk-E's
speed in Km/h over a 1.25Km run down our road. The conditions were icy and snow
covered with no bare sections to get traction on. The only flat section of road
(checked against the elevation graph, not posted) jived with what I thought. The
top speed is about 21Km/h in 6th gear on the flats...
This translates backwards to
approx 2,500RPM on the motor from the spread sheet posted in section one.
Given the above data, I now have
to decide which direction to take in rewinding the motor. Based on the results
from 3 previous motor re-winds of the Dirt-E Bike's motor last year, I have a
good sense that winding heavier copper will raise the RPM/Volt but at the cost
of lowering the low RPM torque of the motor.
In this case my gut instinct is
to rewind the motor with more turns of lighter wire to achieve greater low-end
torque which should raise the RPM of the motor under a comparable load closer to
it's best efficiency. It sounds good to say "Heavier copper" and
"Higher Current", but if the majority of that additional energy is
simply converted into heat, the outcome is far from optimal.
So this section finally closes
with an effective base-line established to gauge any improvements to the motor's
performance, a reliable (though inefficient) gear-box enclosure and a few minor
improvements like the motor mount and additional bracing.
The next section will cover the
motor rewind, brush-plate upgrade and some active cooling.
