|
Tell
3 Friends
I did one better than
that. I told 3 club mailing lists that I belong to (approx.
2000 members total) about your very interesting news
letter.
Take care, -- Rob
|
Hi Rob !
Thanks for your help !! I'm really fired up
about getting the sport of motorcycling the recognition it
deserves. Feel free to post the URL's of Power News
newsletters to your favorite newsgroups or
forums.
Sincerely, Pat
McGivern ~MotoMan |
Back
Issues
Hey
MotoMan,
How can I access all the Power News past
issues ??
Thanks, Paul |
Hi Paul !
All 16 past issues are at the bottom of this
page. I do that on each new newsletter, so they don't get lost
!! Also, the list of upcoming topics can be found in
the "Dynamic Horsepower
Starring: Britney Spears" Power News
Issue.
Sincerely, Pat
McGivern ~MotoMan |
In the last issue of Power News, we
learned that:
1: When an intake
port is too big to provide the velocity necessary to prevent
blowback during the Charging phase, the result is a loss of power at
all RPM's. The secret to more power is to make the
ports smaller.
2: The intake ports
in most modern motorcycles are still waay too big as
they come from the factory !! ...Even for Roadracing use
!!
3: Thousands of motorcycles are losing horsepower this
winter, as many tuners will make their intake ports even
bigger !!
If this is your first issue of Power News, I
recommend that you read last month's edition
first: http://www.mototuneusa.com/think_fast.htm
|
 |
Here's a
Honda F3 that was professionally Flow Bench Ported
(enlarged) to the MAX
!!
This bike was really, really slow
!!
The head measures well
on a Flow Bench, but the engine actually produced Less Power
with this ported head than it did with the
original stock head !!!
|
What Do High Velocity Intake
Ports Look Like ??
These never
before seen photos show the remarkable size difference between
stock and High Velocity Ports:
|
Before:
 Stock Yamaha R6 Intake Port
|
After:
 30 Percent Reduced High Velocity Yamaha R6
Intake Port |
High Velocity Intake
Porting On 5 Valve
Heads: Yamaha YZF 400's, R7 and R1, FZR 1000 &
750
|
Before:
 Stock Yamaha R1 Intake Port |
After:
 30 Percent Reduced High Velocity Yamaha R1
Intake Port |
|
The Secret
to Making Ports Smaller ??
 JB Weld
Epoxy |
Epoxy
!! Epoxy is much easier to work with than welding, and
it offers insulation for the incoming fuel /air mixture. (Cooler
mixture = denser charge.)
This product does the best
job of expanding & contracting with the engine heat without
cracking, or coming loose.
Other products that work well are
Loctite "Metal Set" (available in Europe) and Bondo automotive body
filler.
I recommend the JB Weld because it sets up
slowly, which can be a real plus when you're first learning this
porting technique.
|
Ready To Do It Yourself
?? Here's How:
|

|
Recommended
Tools
1) Dremel Tool
2) Tool
Bits ( Sanding Roll, Stone, Aluminum
Cutter)
3) 60
Grit Coarse Sanding Rolls
4) Caliper For
Measuring Port Height
5) JB Weld (24 Hour
Type)
6) Plastecine Modeling Clay
7)
Dremel Extension Cable
8) Safety Goggles ( Keep Your Eyes !! ) |
|
Clean Up First
(?)
That's right !! Any traces of oil will
ruin the sanding rolls, and make the head an oily mess to work on
!!
So the first step is to wash out all the oil with
dishwashing detergent and hot water.
Use compressed air or a
blow drier to prevent rust. |
. .
 , . |
|

|
Secure The Head
on The Workbench
It's critical that the head is secure and
stable. It's very easy to ruin a valve seat if the head suddenly
shifts while the porting tool is turning at 24,000 RPM
!
Use a 2X4 board to "wheelie" the head into the proper
position.
The clamp-on type light illuminates the ports
from the combustion chamber side. . |
|

|
Get
Centered
The end of this sanding mandrel is
off center. The result will be inefficient sanding action and
chatter marks on the port surface.
Uneven wear on the
sanding roll can cause it to unravel at high speed and possibly
damage the cylinder head.
Here, I'm using a marker to find
out which way the mandrel is bent. By lightly touching it with the
marker while it's spinning, the ink will only show on the "high"
side.
|
|
Careful
... By pressing the "inked" side it against the bench,
I'm bending the mandrel back slightly to perfectly
re-center it.
This takes a bit of practice, because it's
easy to bend the mandrel too much.
If you have
to bend it more than 3 times, throw it out and start over
with a new one. They get weak from being bent, and can suddenly bend
out 90 degrees while spinning 24,000 RPM !! |
.
 |
|
Ready To Port
!!
|
 |
Here's the best way to hold the tool. I let the
dremel motor hang over my right shoulder, and hold onto the drive
cable with both hands.
The bottom of my hands are pushing
slightly against the bench to help steady the tool.
Also,
notice that I've anchored my right hand with my little finger. This
gives the best combination of power and control. With some practice,
you can really let the sanding roll "torque" into the metal without
losing control. |
|
|
|
|
 Use a griding stone to grind the steel valve
guide. Many newer models' valve guides are already flush, so you
get to skip this step.
|

|
|
,
 |
Once most of the steel guide is ground down, use
sanding rolls to make the aluminum boss & valve guide flush with
the port roof.
Then, finish the entire port surface using 60
grit sanding rolls. |
|
. ,
 .
Rough Finish /Grooved Floor |
 60 Grit (Coarse) Sanding Roll Use it to remove the fuel residue, and create a rough port
surface.
|
 Aluminum Cutter Use it to score the port floor to secure the
epoxy.
|
|
Why Not Polish The
Ports ?? Doesn't Air Flow Better on a Smooth
Surface ???
Remember that the ultimate goal isn't "flow"
... it's POWER !!
The intake port is going to flow both fuel
and air. The problem with fuel is that, since it weighs more, it's
difficult to keep it evenly mixed with the air as it follows the
contours of the port.
Boundary Layer
The next time you drive a car in the rain, notice that
when the car is going 60 MPH, the rain drops go up the hood of the
car at walking speed. That's because the smooth surface of the car
creates what's known as a boundary layer, and the portion of that
layer of air that's nearest to the surface is almost
still.
The same thing happens inside an intake port.
Except instead of raindrops, it's fuel droplets that will run down
the port wall slower than the air. That causes a serious change in
the fuel air mixture by the time it reaches the cylinder, ruining
much of the engine's potential power. Polishing the port
walls will ensure that this happens.
The phrase "Port &
Polish" always makes me laugh ... I think the idea came from 70's
Hot Rod magazines or something. Anyways, the last thing you want to
do is polish your ports !!!
Instead, by making a series of
rough 60 grit lines that purposely go against the flow, the
"boundary layer area" will be turbulent, and the fuel will stay
suspended in the air.
Remember: Rough is Good !! |
|
Okay: now that the 1st part of the process is
complete, it's time to prep the head for epoxy -
ing.
First: Wash & Dry The
Head Again !! To remove all the
sanding dust and aluminum chips...
|

|
Here's what the clay is used for !!
It keeps
the liquid epoxy from flowing out and onto the valve
seats. |
|

|
Next, set the head up so that the floors of all 4
ports are level.
On most heads with downdraft ports,
the head will have to be "wheelied" as shown
here. |
Epoxy Mess Avoidance
!! The hardest part about the
next process is not getting yourself covered with epoxy !! My advice is
to wear old clothes, and keep a fresh roll of paper towels on hand
!
Here's a few more tricks I can share with you:
|

|
Cold epoxy is super hard to squeeze out of the
small cap end of the tube !!
So, to get it all out as
easily as possible, I open the JB Weld tubes backwards. Using a
razor to cut open the bottom...
|
|
Then, I use a vise-grip pliers to squeeze out all
the goo onto a sheet of cardboard.
You'll use about 1 package of 2 tubes each (steel
& hardener) per port.
Mix up one at a time.
|

|
|
 Ying &
Yang
|
 Mix It Up
!!
|
|

|
, . Clean the
screwdriver completely, then twirl up a blob as in the photo on the
left.
Keep rotating that screwdriver !!! Remember: The minute you stop, the blob will
drop !!
Application The idea is to add the epoxy to the
deepest point first and then back up. I add the epoxy in "rows". The
first row will flow down onto the clay
barrier. |
|

|
It was impossible to get a clear photo as I added
epoxy into the port, so I'm demonstrating it here on
paper.
To avoid bubbles, start on the left side, and rotate
the screwdriver as you "lay down" the epoxy. |
|

|
Be sure to make the epoxy a little thicker
on the sides.
|
|

|
Then when the right side is reached, twist the
screwdriver as you back it away. That keeps the last strand of epoxy
from getting out of control. |
Here's What it Should Look Like So
Far:
|

|
 Preview: The Finished Port.
|
Now as almost all of the
epoxy is added, you can really see the size difference
!! Notice that the epoxy is slightly
higher where it meets the side walls, to avoid air
bubbles.
|
Don't Miss The Next
Issue: Finishing The Ports !! |

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