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 Welcome To Power
News !! You're about
to learn how to build a "2007
Superbike" ... using inexpensive porting technology, even
before the manufacturers release it to the market !! Be sure to read
the 17 past issues at the bottom of this article. They
contain insights into how engines actually work, and intriguing new ways to power up your
bike without spending a lot of money.
Take a pit stop from the
"information super highway" and spend some time reading these pages.
Get ready to explore fascinating new engine technologies and the
ideas behind the power. I hope you find that you've gained some
valuable knowledge for your time spent here on the pages of Mototune
USA.
Power News is 100% free !! I only ask that
you to help us promote the sport of motorcycling !! If you
like Power News, please forward this page to all of your riding
/ racing friends in your e-mail address list
!!
Thanks !! ~
MotoMan
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The 2007 Superbike
In 1899, this statement was
released by the US patent office: . "Everything That Can Be Invented Already Has
Been" . Looking back over
history, we laugh at many of the ridiculous ideas that were held as
'fact' by the 'scientific establishment' of the time.
At the same time, we are amazed to learn that the true
innovators, the free-thinkers & those who were ahead of
their time were ridiculed or even punished for their daring
to challenge the status-quo ... only to be found correct
many years later.
Hindsight is 20/20 ... but the same
"stuck in the box" thinking of old is still here, even in the
21st century. The 2002 version of this is: "there are so
many people who have thought about this before me, all the good
ideas are taken. "
Throughout civilization, people have
always thought that their time was at the peak of innovation and
invention, only to have the next generation develop newer,
more innovative ideas.
The truth is
that, even with all of our advances, we "know" a lot of
facts, yet actually understand only a little.
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Six Ways To Think Out of the
Box:
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1) Don't
Automatically Believe
Everything You Read 2) Always "Explore The
Opposite" 3) Never Fear Failure 4) When in Doubt, Go For
It !! 5) Never Put Limits On Your
Imagination 6) Read Power News  |
Thinking Out of The
Box To Discover High Velocity Porting: Don't Automatically Believe Everything You
Read Many motorcycle tech articles say that big
bore piston kits give more midrange and less of an increase in top end
power. The reason they give is that the port's ability to breathe at high
rpm's won't be matched to an increased displacement's ability to suck in
more air/fuel mixture.
That seems to make perfect sense,
except that it relies on the assumption that the ports are
the correct size to begin with !!
When I first "over
bored" an engine in 1990, I was surprised to learn that overbore
pistons actually make lots more power at high rpm
!! This is a clue that the stock ports may not be small
enough to provide the port velocity needed for maximum
power.
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New Way To Use A Flowbench
!!
A flowbench
can be used to develop smaller, more aerodynamic
ports.
The experiment I recommend is to
apply modeling clay to the stock ports to test the effects of
smaller port volume on airflow. By "exploring the opposite", you can
learn more about how to gain
something:
By first
learning how to lose it !!
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 A Superflow
Flowbench
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Using Clay
For Flowbench Testing
One of the problems with porting, is that by
the time you find out you went the wrong way, the cylinder head may
be ruined ($$$).
By adding clay to the stock ports, you
can "ruin" the flow without actually ruining the ports. That's the
best way to learn where the least "flow
sensitive" areas of the port are.
Here I've
added clay to 1/2 the port, so it's easier to compare the size
difference of high velocity porting.
If an area is
unaffected by the clay, you should try adding more. Using this
method, an accurate "picture" of the flow characteristics of a port
can be visualized. Doing something "wrong" is sometimes the best way to figure
out what's "right" !
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Always "Explore The
Opposite"
In this
case, there was a huge surprise !!
The photo on
the right shows how much clay can be added to both sides of
the port floor. The airflow, as measured on a
flowbench remains the
same !!
How is this extra
space in the port helping flow or horsepower ??? It isn't, the area
in the port that is unaffected by the clay is just
dead space.
The port's airflow
is mostly determined by the valve size. Extra space in the port only
lowers the velocity.
There's lots of unnecessary dead space in the ports
of most (1985-2002) multi intake valve Japanese motorcycle engines
!! |
 There's this much
dead space in a Honda CBR 600 F3 intake
port
If you own a
flowbench: It's tempting to
want to increase the port flow, but it's much more important to
increase the velocity !!
Most modern engines already have
more than enough flow in the stock ports. What they need is more
velocity. I've intentionally made the ports so small that they
flowed 8% less than the stock ports. These high velocity
ports always make the best midrange and top-end power
!!
Do the "clay test"
first !!
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Never
Fear Failure If a port can be made
smaller without losing flow, then it seems logical that there should be a
midrange gain, and you can consider that knowledge a win. On the other hand, if the
bike turns out to be slow, it could be embarrassing !! But it wouldn't be
failure, because it you'd learn a new way that didn't work, and that
knowledge is a win as well !! Either way... you win
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Never Fear Failure |
Never think of "failure" as failure, only as a
valuable guide that re-directs you in the right
direction.
It's not easy to do, but when you
decide to truly apply this concept, you'll never lose
!!
The only way people fail is when they're too afraid
and don't do anything. |
When in Doubt, Go For It !! As it turned out, I got "lucky", because when I first tested
this porting idea in 1993 on a Honda Hawk at Daytona, there
was both midrange & top end power gain !! Every multi
intake valve engine I've tried it on since then has had a similar
power increase. " Luck "
really is just a matter of "Going For It " enough times.
The Good News Is: You Don't Need A Flowbench !!! (I haven't used
one in many years, and have won hundreds of races using this simple
formula.)
The 65% Port Reduction
Formula : For best power, the choke point
height should be 65% of the diameter of the intake valve !!
An inside caliper is used to
measure the height of the tightest point in the port. This is
called the choke point, and it's located between the floor
downturn, and the roof of the port just before the valve guide.
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The only area that gets
enlarged:
In order to make room for the porting tool,
the intake valve guides should be ground down. This is the
only area of the port that should be
enlarged.
Never grind down the exhaust valve
guides. |
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Measure the intake valve diameter. This
Honda F3 valve is 1.006 inches. |
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Use an inside caliper to measure the choke
point... |
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The outside caliper is set to the valve size
1.006 inches X .65 = .654 inches.
In this photo, the inside
caliper is set to 65% of the valve, or .654 inches.
The
white line compares the 35% difference.
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Here the caliper is at the choke
point.
After the epoxy is in place it will be sanded
down flat, until the calipers can fit into the .654 inches choke
point. Only the height is decreased, while the width of the port is
unaffected. |
Which engines does it work on
?? These are the cylinder heads I've high
velocity ported to 65 percent of the diameter of the intake
valve:
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In each case ...
...
the engine made an all rpm power increase of 6-8
percent !! |
Yamaha FZR 750
& 1000 FZR 400 FZR 600 R6, R1 & R7 YZF 600
(Thundercat)
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Suzuki GSXR 600 -
750 GSXR 1100 TL 1000 R&S SV 650 |
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Honda Hawk NT
650 CBR 600 F2, F3, F4,F4I CBR 900 - 929 etc... |
Kawasaki EX
500 ZX6,7,9,10,11 KLR 250-600 Vulcan 800
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" Too Much Velocity ??
"
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Honda F3
In 1996 I built a Honda F3 for
the new 102 hp class. The rules allowed any engine modifications, as
long as the bike didn't exceed 102 peak hp. on the official race
dyno.
The engine had Wiseco 2 mm overbore
pistons (636 cc's) and stock cams. Most F3's with this set up made
around 99 - 100 hp with stock ports.
My customer wanted
to be careful not to go over the limit, and he set a goal of 98 hp.
I made the ports much smaller than I normally did, and when I flow
tested them, they flowed 8 % less than stock
!!
It seemed logical that if the ports had "too much
velocity" the bike would gain midrange and lose 3-4 hp at high rpm.
Using calculations derived from flow testing, I predicted that the
engine should make 96 - 98 hp.
When we got down to the first 102 race at
Daytona, I broke the engine in with about 6 dyno runs. The piston
rings were definitely not 100% sealed, but the engine was ready for
it's first full power dyno run.
The midrange was awesome, and
it made 103.8 peak HP ... nearly 6 horsepower more than my
prediction !!
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Does reduction porting
increase the port's turn radius, to make the ports more
"downdraft" ??? No On the newer,
more "downdraft" cylinder head designs, this technique actually
causes the port to become less
downdraft.
The idea isn't
to increase the port's turn radius or make it more downdraft, or
even to make the air "flow" more
easily.
It's all about making the port a lot smaller
for higher flow speed.
The ports that make the most power
actually lose some "flow" as measured on a flowbench
!!
Remember: Velocity has a Greater
Effect on Power than Flow does !!
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Pushing The Limits 1 Step Further
.... Getting Down & Dirty !!
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The KLX 250 ~
365 "SuperDirtBike"
This motor had a 5mm larger bore, and a 9mm
longer stroked crank, which increased the single cylinder's capacity
to 365 cc's !!
That would be like enlarging a 1000 to a 1460
!!
With a huge 46 percent increase in capacity, you wouldn't
think the ports would benefit from being reduced. |
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One year before the motocross world was
waking up to the reality that the 4 stroke Yamaha YZF 400 could
rival 2 strokes in all out power...
This KLX project
was already blowing away 2 stroke 250's !! |
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The Secret
!!
Every possible area in the port was reduced,
including the bowl area !!
By applying clay to the bowl area during flow testing, I was
able to find another area of "dead flow space" in the KLX head. The
epoxy really speeds up the intake charge past the valve and into the
huge 46 % bigger cylinder.
The extremely rough surface finish
helps to keep the fuel and air mixed as it enters
the cylinder. |
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Finishing Your High Velocity
Ports: In the last issue we finished the port
surface, and roughed it up in preparation for the epoxy. Next,
modeling clay was used to keep the epoxy from running out past
the valve seats. Then the ports were filled about 40 % with
liquid epoxy. Let the epoxy set for at least 24 hours.
Now the
clay's been removed and the epoxy is ready for finish porting:
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First, sand down any irregularities in the floor,
and set the 65% choke height. |
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Don't sand on the sealing rim of the
port !!
Instead, use a razor to cut off any excess
epoxy. |
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Use a thin grinding stone to get out
most of the extra epoxy from around the valve seat area....
 60 Grit (Coarse) Sanding
Roll ...then use the 60 grit sanding roll to
match the epoxy to the narrowest point in the valve seat
insert, and to create
a rough port surface.
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 Be SUPER careful when
you're removing epoxy near the valve seat area
!!
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 Avoid the sealing
area of the valve seat at all costs !! One nick with the porting
tool will ruin the valve seal.
Also, be extra
careful not to touch the lower valve seat angle. This port's flow
has been ruined by another tuner who eliminated most of the lower
angle !
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Get a Grip I
grip the porting tool with both hands, also notice how I anchor my
little finger to get maximum control of the tool.
Rotate the
sanding roll in a circle to match the epoxy to the port throat. Keep
the porting tool moving at all times to avoid digging into
the epoxy.
As the aluminum and epoxy start to get
matched up, put less pressure on the (softer) epoxy so it doesn't
"sand" faster than the aluminum.
Ideally, you want the epoxy and the aluminum to
blend perfectly, there should be no steps or depressions in the
epoxy.
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Caution: When you're rounding the sharp
angle from the floor to the valve seat, watch out that the sanding
roll doesn't hit the valve seat on the other side
!!
(It's easy to ruin a valve seat) |
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Next, use a strip of coarse emery cloth to get the
radius almost perfect ... |
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For the last step, use a drop of super glue on a
piece of emery cloth... |
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... to keep the sandpaper from falling off your
finger !!
This will make the floor radius smooth, which is
the most important area in terms of flow.
The intake ports are done !! |
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Where To Get
Porting Bits:
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  Assorted Dremel
Grinding Stones Available At Most Hardware
Stores
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 60 Grit (Coarse) Sanding
Roll & Pilot
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MSC Industrial Supply 1 800
645-7270
60 Grit
(Coarse) Sanding Roll Box of 100 Part
Number: 09898701
Pilot Part Number:
09900663
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...and now to answer the question
you may be wondering:
Why don't the
manufacturers know about smaller ports ???
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MotoMan |
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"They
Do." ! ! ! ! ! ! ! ! ! |
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Think about your answer to that one
!!
... and I'll explain my answer in the next issue of
Power News, which will be all about: Exhaust Porting !!
Have a Cool Day
!! ~MotoMan
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Wow ... There's 17 More
Back Issues !! Each Article Builds On The Last
... So For Best Power Results, Please Read Them All:
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