FAR FROM BORING
The days of cylinder boring are slowly fading away,
and the changing of the guard is now represented by
a handful of small scale Nikasil cylinder
reconditioners. We spoke to one of Australia's
leading specialists in the field, LM Electroplating,
about the technical process, why they reconditioned
cylinders and what's in it for you.
The worst sound a rider can hear is the unmistakable
destruction of a top-end. When a circlip decides to
take a wander into the busy world of moving piston
and stationary cylinder, most would say it's
definitely all over for your $800 cylinder. What
most bike owners don't realise is that when they
look at a hole or score midway up the cylinder, it's
not necessarily time to toss it in the recycling
bin.
We'd heard round the traps that there was a way to
sidestep the $800 cylinder replacement cost with a
half price alternative. Immediately we had to wonder
about quality. But we'd also heard that the Kawasaki
race team used this mob for the recoating of even
their stock cylinders. We know plenty about overseas
cylinder reconditions, but nothing about those that
operate locally. We just had to send the ADB tech
inspectors for a snoop into the silent cylinder
closet.
A full day at LM Electoplating Industries, and we
were dumb struck that no one had really uncovered
some of the great stuff these guys do. Rob and Larry
Houghton from LM have delved deep into the mystery
of cylinders, and now sell the product of their own
process, Electrosil, as a viable means of recoating
and reconditioning stuffed cylinders for around half
the price of a new unit. The quality of finish is
outstanding, as illustrated by the backing of
Kawasaki, and the process it local. We were starting
to like them already.
Cylinders
Firstly, let's take a look at the two main sorts of
cylinders so we can better understand the sort of
work that Rob and Larry from LM do. All cylinders
are mostly aluminium but this material is too soft
for contact with steel piston rings. This means that
all cylinders need a liner. Bike cylinders come in
tow main sorts - ones with boreable cast iron liners
and ones with Nikasil liners. LM Electroplating work
only with Nikasil cylinders because that's what
performs best and is most popular.
Nikasil Coatings
The Nikasil coating is essential, and must stay
intact to keep your engine going. Any little
scratches and the coating will be stuffed and the
top-end won't last much longer than a sprocket with
one tooth left on it.
The cylinder coatings from each manufacturer are
generally referred to as Nikasil, but vary markedly
in the actual composition of the Nikasil. Nikasil is
an abbreviation for a Nickel and Silicon Carbide
composite, which usually runs at about a 14 per cent
Silicon Carbide ratio. Nikasil is a lot like
concrete in that the Silicon Carbide acts as the
sand and gravel, while the Nickel acts as the
cement. The composite form a matrix, which binds
very tightly and provides the strong surface
required to withstand the force of a slapping
piston. The Silicon Carbide particles stand as
little peaks on a microscopic level, while the
Nickel holds the peaks together. The two-stroke
lube, or the engine oil on four-strokes, sits
between these peaks to form a lubricating surface
which allows the piston to move easily at high
speed.
LM Electroplating Industries have their own stuff
called Electrosil. Electrosil is the same as Nikasil,
except that LM's Electrosil is its own blend of
Nickel, Silicon Carbide and select additives. LM
have taken four years to develop Electrosil through
extensive R & D and surface studies.
When does your cylinder need recoating?
When you've seized your bike, broken a piston
or ring (both will scratch your cylinder lining), or
just worn through the Nikasil, you'll need to either
replace or recondition your damaged cylinder. LM
recondition cylinders to standards as good as, if
not better than, stock. They can also fill holes in
the cylinder wall, take bores back to round after
being oval, and then recoat the cylinder with their
own product, called Electrosil. According to LM,
motorcycle manufacturers have cut down Nikasil
coating thickness to the bare minimum, and sometimes
below. Also, Kawasaki use a process to coat their
cylinders called electrofusion. This process is far
less accurate and more likely to give trouble. The
Kawasaki race team ports and then gets their stock
cylinders recoated by LM before they even use them.
For serious race turners, LM also recommend that
stock top-ends on all bikes are stripped and
blueprinted to remove any small burrs or debris from
assembly. In the meantime though, inspect your
cylinder liner next time you tear down the top-end
for any dull spots or scratches. pay particular
attention to the exhaust port area, as this part of
the cylinder cops most flak.
The Process
Here's what LM do to the cylinder from when it
arrives in a couriered box till when your
screaming in the phone a day later so you can get it
back for the next "big race". For future reference,
turnaround time is approximately 10 to 14 days
(Editor: now 3-4 working days).
So you've just wrecked it. You've got your scored,
holed and scratched cylinder and you want it fixed.
You give it a tub, remove all studs and powervalves,
and send it off to LM. LM use a multi-stage cleaning
process which actually strips all grease and dirt,
and even the old Nikasil from the cylinder. If the
powervalves were left in, they would be melted out
too. Note on this cylinder the shiny bits around the
ports. This is stuffed because the piston has worn
though the coating and actually scrubbed a bit of
itself onto the cylinder.
What's left after the cleaning process is just the
cast aluminium cylinders, which Rob and Larry call a
blank. This is a Husky cylinder which is about to be
checked for irregularities in the bore.
The blank is given a light hone on their customised plateau honing bar (definitely not any
old ball hone). This reveals any high spots. Usually
when a bike seizes, the position will scoop a bit
out of the cylinder. This cannot be plated over. The
blank cylinder has to be perfectly round, and the
right size to match the piston (which has to
be supplied when you give your cylinder
to LM). If there are high spots, the blank cylinder
is bored back to round, and square to the base of
the cylinder. This is a KTM cylinder with a big low
spot about the exhaust port.
Any porting or welding is also done at this
stage to the cylinder blank. This is where LM also
bore cylinders to match big bore pistons. Before the
next stage of the process, the cylinder is
crack-tested with an acid solution. Once all this is
done, the cylinder is ready for replating.
LM's Electrosil is deposited on the aluminium blank
with a dipping and plating process called
electroplating. We weren't allowed to take photos of
this top secret section of the process so we'll have
to sue a few words. The cylinder is given a positive
charge, while an Electrosil rod is negative in a vat
of salty solution. Positive attracts negative, and
so the material flows from the Electrosil rod onto
the cylinder. The Electrosil is deposited on the
bore at a constant rate, so that the longer the
cylinder is dipped for, the thicker the coating.
That means LM can coat their cylinder to custom
thickness to give greater longevity or to compensate
for when the cylinder is bored to straighten an oval
or warped shape. LM have devised a way similar to
that of Yamaha, Honda, Suzuki, Husky, KTM, and Honda
(Kawasaki use a different process), whereby they
mask the cylinder so the electroplating only occurs
on the cylinder bore, and overlaps just slightly
into the port areas. To plate the whole cylinder
would be a huge waste of material, the stud holes
would be ruined, and the powervalves wouldn't fit in
the cylinder any more. The actual electroplating
process is highly secretive because cylinder
manufacturers and LM don't want to give away how
they mask everything except the cylinder's bore.
Also, the Silicon Carbide to Nickel ration and
additive selection is kept a secret.
 Once the cylinder is plated, it is given a
light hone on the plateau hone and measured to see
the coating thickness fits the piston perfectly.
 LM time the dipping process perfectly so that
the cylinder usually comes out with exactly the
right thickness of coating. Note how the plating
laps over into the ports just slightly. Also, the
bore is left perfectly smooth and shiny. Your
cylinder is ready to race.
Nikasil - the common mistakes
Many bike owners and even bike shops take to
ports with a grinder in an attempt to
scavenge horsepower from their stock
cylinders. Porting is carried out almost
everywhere the wrong way - in a way that
leads to a stuffed cylinder. In stock form
and after Electrosil have recoated a
cylinder, the Nikasil coating is "keyed in",
or wrapped around the port edges, to give
the rings a perfect seal as they travel up
and down. Most porting cuts the coating
around these edges where the bore feeds into
the ports. This breaks the critical Nikasil
coating around the port edges, and will
always lead to flaking of the Nikasil. It
won't take long before the cylinder has to
be recoated. The lesson is that porting
should only be done if the cylinder is going
to be recoated immediately.
Also, may mechanics use a ball hone on
cylinders before reassembling during a
top-end rebuild. Ball hones are used to
create fine oil retention paths on cast iron
cylinders. On Nikasil cylinders, however, a
ball hone won't do this. Instead, a ball
hone will knock the Silicon Carbide peaks
from the coating which wrecks the surface's
oil retention capability. Ball hones are a
bad idea for use on Nikasil coatings. LM use
a special plateau hone, which they developed
specifically for Electrosil. The main reason
they use the hone is to aid with ring run-in
more than oil retention. Nikasil cylinders
should be cleaned but not ball-honed before
reassembly. |
How are LM better than the rest?
LM only do 40 cylinders a week. They do not
batch-coat cylinders, like all the major
cylinder manufacturers, preferring to work
with each cylinder to get the most precise
thickness in the coating and a better match
to the piston. This is one of the points
that LM prides itself on. Its cylinders are
coated to within a two micron tolerance,
which is five times more accurate than
stock. This means the piston will fit better
in the cylinder at operating temperature and
cock less in the bore as it goes up and down
which will increase the life of the
cylinder. LM's coatings are thicker than on
any stock cylinder, which means that the
cylinder will last longer. The coating can
be laid up to half a mil thick and is at
least two thou thicker than any stock
coating. Also, LM's Electrosil and
electroplating process have taken eight
years to develop to their stringent
standards. |
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