"The Scientifical ~ Mystical One"

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Intake Porting Secrets Part 1

   V  i  e  w  e  r       F  e  e  d  b  a  c  k
Engine Work 
Hey MotoMan:

I'm a racer in WMRRA & OMRRA [Washington & Oregon, USA] racing organizations.  I am one of the top competitors in the northwest, but had been plagued with under horsepower machines.  I have watched [Mototune] competitors such as Alan Schmidt, Dave Cook kick my ass down the straight and quite frankly I am sick of it. 

For the 2002 season, I want to be able to be competitive down the straight not just the corners.  I have seen what your motors have done out on the track, so there is no question on who I would like to use to build my motor.  I just need you to answer a few questions.
How much does it cost to have you build a supersport motor? How much does it cost to ship a motor? What kind of time frame do you need? How much horsepower are you getting out of the new GSXR-750's. If I purchase another bike, and have you build two motors for me--is there a price savings? Information ?

~ Mark

Hi Mark !!

Thanks for the awesome testimonial for Mototune !

I originally started the Mototune USA website in late 1999 to promote Mototune (my engine building business.) In the past year, the website has really taken off, and recently I've had over 900 e-mails from people who've wanted me to build their engines. It would take me 30 years to build that many motors !

I can't do both anymore, so I made the decision to quit building engines, and do the Mototune USA website full time. Power News is promoting both sports of street motorcycling and roadracing.... we're making it go "
mainstream" !!

I know it's hard to find good engine tuners. A big part of the problem is that there's a lot of misinformation about motorcycle performance in books and magazines. The secrets you'll learn here in the Power News newsletter will level the technological "playing field". People from all over the world will be able to build bikes that are as fast as Alan Schmidt's and Dave Cook's. 

If you don't want to do the engine work yourself, I'd recommend finding some mechanics you can trust, and tell them to sign up for Power News ! 

  Pat McGivern


5 Stars !!!!!

Hey MotoMan, awesome site packed with great info !

I just got a new GSXR1000....I have to admit, I'm a little skeptical about your break in procedure, although it does make sense......

Its just hard to go against the manual after paying 9000 dollars for it, being 20 years old that's a lot of loot, but anyways,

5 STARS!!!!

~ Corey

Hi Corey !

Thanks for the high rating !!
It's true: my "Break in Secrets" method is definitely the way to get the most power & best ring seal for your new Suzuki !!

A word of warning: Everything you're going to read on Power News is hard-to-believe, and will tend to make you skeptical !! 

The way Mototune was able to beat the performance of the factory racing teams, was to do everything differently than others do it. But, just like the "Break In Secrets" article, once you understand the ideas, it will make more sense than the "cutting edge" information you find in magazines.

Please tell all of your riding friends to subscribe to Power News !!

  Pat McGivern


Mototune USA Fans !!
This is just one part of an ongoing tech series available for free to Power News Subscribers. 

I'd like to invite you to become a Power News Subscriber !! Upon signing up you'll immediately receive the secret links with photos and instructions on how to high velocity port your own cylinder head. There are also lots more articles that will give you new insights into improving modern 
high performance engine technology. 

It's free, just fill in your e-mail in the sign up form at the bottom of this page !!

Pat McGivern


756,220 to 1 !!
At the time this article was written in late 2001, when you typed the words "Intake Porting" into the Alta Vista search engine, 
you'd find an incredible
756,220 pages related to this topic !! 

Every one of those pages will tell you the
exact opposite of what 
I'm going to teach you today. 

The odds are overwhelmingly against the MotoMan on this one:

That's over
Three-Quarters of a Million against 1 !!
(That's not including another 'zillion' books, magazines and other tuners...)

The Honda Hawk Experiment

In January of 1992, I first studied the effects of porting on my own race bikes, and made a huge discovery. It worked so well, that after a summer of working on other people's bikes, I could show up at the local racetrack in August with no practice and easily win races. 

At Daytona in 1993, I was able to test my idea against the best in America. Like every fast Hawk rider at the time I had the 700 cc (3 mm over) piston kit, a pipe and the popular racing cams. My carburetors and everything else inside the engine was stock, except for my secret porting trick. 

The competition ?? The top racers had their Hawks built by a company called Two Brothers which, based on their huge success with Hawks, went on to become a semi factory Honda race team. 

Gridded on the very last row, I came out of turn one in last place out of 43 riders !! (I always freaked out on starts) Once the tires warmed up, I realized I could easily out accelerate the Two Brothers bikes as well as everyone else in the race. At one point, without using the draft, I passed 11 of my fellow Hawk riders at once on the fastest part of the banking. In the short 4 lap race, I passed 38 riders to take 5th place Expert in my first time at the track. 

Since then I've ported about 100 heads from every major brand and type of 4 stroke engine. The result has been shattered lap records, countless USA roadracing championships, and another 2 in Europe. On the street, I've built a few real "sleepers" in the USA, and created a genuine "street legend" in the Dominican Republic !!

There was no way I could hide the evidence of this porting technique, and it's amazing results, so I thought for sure that it would only be a matter of months before everyone else caught on. I was convinced that the advantage of my new "secret weapon" would be over by early 1994. 

It's been exactly 10 years since my discovery, and with very few exceptions, no one else has gotten it. 

How could that be ?? Motor sports are supposed to be so ultra competitive that no one can hold an advantage for long. With the vast manpower & financial resources of the big racing teams, how could 1 guy from Wisconsin hold onto all the chips for 10 years?? 

It made me realize that there are similar situations like this in every endeavor all over the world. That's why I came up with the motto "get past the cutting edge". I'm here to tell you that the "cutting edge" is artificial, and whatever you do, you can beat the best. No one's unbeatable at anything, once you truly understand the power of thinking outside of the box.

I've realized that the answer to how easily I was able to protect my "secret" ... really lies in an understanding of human nature.

The information I'm going to share with you will certainly change the face of engine performance & technology. I also sincerely hope it will inspire you to look deeper into the ways that we  "automatically think" ... 
                             ... without ever actually thinking.

The Magical Myth of Flowbench - Porting

Once upon a time...
he flowbench is a machine that measures the airflow through the ports by sucking air thru like a vacuum cleaner. The vacuum gauges on the bench actually measure the resistance to the flow thru the ports, and the result is converted into CFM. That means "how many Cubic Feet of air will flow through the port per Minute." 


Anyone who buys a flowbench and a dremel tool is "qualified" to flowbench - port heads. The Superflow flowbench owner's manual says that:

                      " For every 1 CFM  of increase in intake flow, 
                                     you'll gain .43 horsepower. "

                               If you want more water to flow through a pipe, just make the pipe bigger
                                                         There's something wrong with this though.


It's easy to understand why so many people automatically think Flowbench - Porting, or "more is better" is a way to improve power.
Without closer examination, 
it seems quite logical. 

 Okay, Let's examine it a little closer !!

We were all taught to think of a 4 stroke engine by the traditional textbook explanation of Intake, Compression, Power & Exhaust. 

Textbooks and magazines achieve a sort of instant credibility that comes from the association with $$

"This source must be right ... after all, there's obviously
some big money behind it ..." 

Because of this association, the vast majority of people never question the things they learn in school, or read in mainstream publications.

In the last issue of Power News you learned to think of a four stroke engine in a whole new way... 8 Phases !!

In the 8 phase engine article, 
you'll remember that the intake "stroke" 
actually consists of 3 phases

( Overlap, Suction and Charging. )


Stock Yamaha R6 Intake Port

Uh - Oh ...
It turns out that a flowbench measures the least  
important aspect of intake cycle efficiency !!

Stock Yamaha R1 Intake Port

It's true !! 
When you stop to think about it, a 
flowbench only measures the efficiency 
of the "suction phase". 

     That's not the right 
      thing to measure.

Why ?? 
Because, it doesn't matter how well 
the cylinder is filled at that point in 
the intake cycle ! 

What ... that sounds crazy !!!
It's 100% true ... it's simply a matter of the sequence of events ! The success of the last event, the charging phase, determines the success of the entire intake process. 

What happens when a low velocity port fills the cylinder really well, but too early ?? The result is a slower intake charge that stops flowing into the cylinder. Then some of the charge gets pushed back out of the cylinder and into the port as the piston returns up the bore during the intake charging phase. The gain in flow doesn't offset the loss in port velocity.

Here's an analogy:

It's just like a roadrace; you can lead for 3 laps, then run out of steam and end up in 7th place.

In racing, only the last lap counts, because the one who leads at the checkered flag wins.

In the intake cycle "race" the last lap is the charging phase, 
and the checkered flag is the intake valves closing.

So in the final result, the first 2 phases don't matter if the 3rd phase is unsuccessful !! The total intake volume that will be burned is determined by the amount that remains in the cylinders after the intake valves close. That means that an early gain during the suction phase can be easily lost during the charging phase. And, if the intake charge returns back into the port during the piston's upstroke, the result is going to be a net loss !! 

It gets worse !
On a carbureted bike the reversing charge will create an effect called double carburetion, which means the mixture will become even richer with fuel as it passes back over the main jet nozzle for a second time. 

Have we lost enough power yet ??

Wait... it gets even worse !!
Here's a real "out of the box" idea: high flow ports also flow really well backwards !!! All that work on the flowbench comes back to haunt you when the piston now has even less resistance to pushing the intake charge back into the " high flowing port " !!!!!!!  When you begin to consider the consequences of all this, the whole idea of "more flow is better" comes crashing down like a lead balloon.

What's The Secret ??
Using the race analogy, if you increase the
Port Velocity, by making the port smaller, the intake cycle "race" starts out slower, gains momentum and makes a tremendous charge on the "last lap" to overtake the high flow port and win the "race". The interesting thing is, this type of port will always lose in a flowbench contest !!!


The Scientific Method:

one set of conditions. Make only one change, test the result and compare it to the first set of conditions.


"Why hasn't anyone thought of this before ?!?!"

One reason is that people only think of "Scientists" as scientists. Everyone can and should be a scientist !! That means you !!

In real world situations, many people forget to apply the simple principle that all productive science is based on: The Scientific Method.

When someone builds a superbike engine, they usually port their cylinder heads and make other modifications like higher compression, valve job, different cams and big bore kits. 

The combination of all these modifications usually results in a net gain in power. The problem with attributing a gain to the porting in this scenario, is that it goes against the scientific method, because there are 4 other variables coming into play.

Know the difference between association and causation

In this case, flowbench porting of the cylinder head has been associated with horsepower gains for so long that no one bothers to question it. That doesn’t mean the porting actually caused any of the gain. 

Could More Flow = Less Power ??
Flowbench Porting has always been associated with more power...
Superflow even says more flow equals more power in their official owner's handbook !!
Yet, in most cases, Flowbench Porting modern cylinder heads actually results in less power! 

(Actually, a few creative thinking tuners in Europe do already know about this. They're not anxious to reveal this info, because their success on the racetrack is somewhat dependent on it remaining a secret.)

What happens when we apply the scientific method 
to intake porting ??
To find out, let's test 2 progressively smaller porting specs against a stock head, 
without changing any other variables ...

I chose the Yamaha R6 for this test,
because it has the least flow 
and the smallest valves of all the current 600's !!

Then I asked the question: 
Are the stock ports still way too big ???

The Verdict ??
Smaller Volume = Higher Velocity
Better Power

By reducing the intake port size by 30 percent: 

The Yamaha R6 increases 5 hp. from 103.1 to 108.3 That's a 5 percent gain in top end power !

Notice that the power gain at 8,000 is from 60 to 65, also 5 hp...

That's the same hp increase, but it's actually an 8.4 percent gain where it makes the biggest difference, at the turn exit.

30% Smaller Ports make the most midrange & top end power !!

       -  Stock Ports 103.1 HP
20% Smaller Ports 104.1 HP
       - 30% Smaller Ports 108.3 HP !!

             Click Here For The Full Size Version

How do High Velocity Ports work on the racetrack ??
" Incredible !! "

With most common superbike modifications, the rear tire either spins up too fast and threatens to highside you, or it grips and ungrips, 
which makes the bike drift wide and run off line. 
Either way, the rider has to wait longer to roll on the throttle !!
What's the point of modifying an engine if you can't actually use the new found power ?

The enhanced power delivery of the
High Velocity Intake Porting allows for 
perfectly controlled rear wheel sliding, which is actually 

more important than the gain in peak power !!

600 Lap Record Smashed on a Borrowed R6 !!
In May of 2000, Derek Shoeberle borrowed an R6 from one of my customers. On that super windy Sunday in May, the races were dominated by the man on the mysterious red bike. Not only did Derek smash the 600 record, he came within 0.88 of a second of the overall motorcycle lap record ... 

... which was set in 1993 by
an FZR 1000 with Mototune High Velocity Ports !!

High Velocity Intake Porting  
A power improvement that enhances your suspension, and dramatically improves rear tire traction !!

In addition to the overall peak power gain, the biggest advantage of Mototune High Velocity Intake Porting is its perfectly linear power delivery. When you open the throttle two percent, you get exactly two percent more horsepower, then when you want ten more, you get exactly ten percent. 

When you look at the photo,
notice how Derek's confidently turning the throttle on while he's still at his outrageously steep lean angle ... through one of the bumpiest turns in roadracing. That's smooth power !! 

Super - predictable mid range power delivery makes it easy for anyone from novice to expert to get incredible drives off of turns, since the power doesn't break your rear tire loose like it does on most superbikes. It doesn't take much practice to turn the throttle harder, it just intuitively feels right when the power is so smooth.

That Confidence Makes a Huge Difference in Your Lap Times !! 

The increased driveability and top end speed from the High Velocity Intake Ports allowed Derek to ride at an entirely new level. During this race he absolutely smoked 2nd place, and turned an incredible 1:13.88, lowering the Blackhawk 600 lap record by over 1 second 
on a very windy day !!

Derek Shoeberle Powers Through Blackhawk Farms Raceway's Notoriously Bumpy Turn 4

" High Velocity Intake Ports
Are Incredible !! "

 What if your head's already been flow bench ported ??

CBR 600F3
Before & After

The Blue Line represents a cylinder head that was "flow bench ported" by a well known U.S. motorcycle performance tuning company. 

The Blue Line shows that enlarging the stock intake ports a small amount, caused this engine to lose power throughout the entire power curve.

The good news is, The Red Line shows that after fixing the "flowbench ported" head by  making the ports 35% smaller... this CBR 600F3 gained more than 10 HP !!

Since The Blue Line's head ports were already "flowed out" even bigger than stock, there was about an extra 3 horsepower recovered.

In this case, a stock head would have worked better than the flowbench ported head. 

Flow Bench Porting usually costs 
around $500 - $1,000 ...  

,It's a total waste of money !!
 This dyno graph dramatically shows the power loss caused by lowered intake port velocity:

The difference at the beginning of this dyno graph is because the dyno operator opened the throttle for the red run at a later rpm point than the blue run. 

The comparison isn't accurate until both runs are at full throttle and full power, which is at about 35 mph on the graph.

More Flow Doesn't Always  Equal More Power !!

Less Velocity Usually Equals Less Power !!!

How does 
   go unchallenged ??

1) Failure to use the scientific method !!

2) A lack of critical thinking about existing information !!

3) Follow the leader mentality !!

4) Fear of being different !!

5) Blind trust in books and magazines !!

6) Mass marketing !!

7) Because changing the way you think is scary !!

8) All of the above !!

(Of course, the correct answer is #8)

" It's Time Somebody Did Something About Bread !! "

Bread is Evil.

Did you know:

1) More than 98 percent of convicted criminals are bread eaters !

2) Exactly half of all children who grow up in bread - eating households score in the bottom 50% on standardized IQ tests !

3) In the 19th century, when virtually all bread was baked in the home, the average life expectancy was less than 55 years; infant mortality rates were unacceptably high; many women died in childbirth; and diseases such as typhoid, scarlet fever, smallpox and influenza ravaged entire nations !

4) Statistics show that more than 75 % of violent crimes are committed within 24 hours of eating bread !

5) Bread is made from a substance called "dough." Researchers have proven that as little as one pound of dough can choke a large animal like a horse. The average person eats more bread than that in one month !

6) Bread is known to be extremely addictive. Subjects deprived of bread and given only water, actually begged for bread after just two days !

7) Bread is a "gateway" food item, which usually leads to such items as butter, jam, peanut butter and even ... bacon !

8) Bread has been proven to kill. Scientists have now uncovered alarming evidence that 100% of the people who eat bread will eventually die !

9) Unattended newborn babies can choke on bread !

10) Bread is baked at temperatures as high as 425 degrees Fahrenheit ! Don't laugh...that kind of heat can kill a full grown adult in less than five minutes.

11) 96 % of cancer victims eventually admit that they've eaten bread !

12) Sadly, 9 out of 10 bread eaters are unable to distinguish between significant scientific fact and meaningless statistical babbling.

                               (Not Critical Thinkers Like You !!)

One could argue that every one of these individual "factoids" about bread is "true."  The way the "factoids" compare bread with danger, and the use of official - statistical -  scientifical sounding words cause the unthinking reader to make connections of logic that aren't true. 

The only one that's true is #12. 
The others falsely imply new information that really isn't there !!

(The very real problem is that much of the information in our modern society is presented this way.)

Don't Miss The Next Issue:
Learn How To High Velocity Port 
Your Own Cylinder Head !!




  Free Superbike and Supersport Power Secrets !MotoMan's 
The All New Power News Magazine
Superbike, Auto & Snowmobile 
Engine Info !!

Learn How to Do it Yourself:
High Velocity 
Intake Porting !!

Smaller Ports ... Unlocking The Mystery Between Flow & Velocity

Smaller Intake Ports Gain 7 % More Power

Dear Reader,

As of October 29, 2011, Power News will no longer be subscription-based, and there won't be update notices via e-mail. 
Please bookmark http://www.mototuneusa.com 
and check back for future updates !!

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