After the last Power News came out at the end of April,
the porting articles were
the subject of many forum discussions around the internet. That's great !! The strange thing is,
every one I saw gave the idea two thumbs down !!
Some even used naughty words !
One said the idea of making ports smaller as being "the stupidest idea ever" and another
said "who does this guy think he is ... the next Rob Muzzy ???
(Not at all ... in fact, in 1995 one of Muzzy's contracted superbike riders let us sneak into the
semi truck and get a look at the Factory ZX7 Superbike ports. We peeled back the duct tape to
find to our dismay, that Muzzy was making the intake ports bigger than stock !!!)
Power News is not cutting edge information, it's
beyond the cutting edge ... meaning
it's a little "over the top", and as such it's bound to get some people upset, or at least
cause a debate about my sanity for saying all this.
( I promise not to get offended )
You know... I could talk about high velocity ports all day long ...
... but the best way to really prove it works,
would be to hear reports from Power News readers from all over the world,
who trust me enough to:
Take Action And Do It !!
That's what Power News is all about !!
I've won at this sport for 10 years, and I'm now turning the Power over to YOU !!
So let the e-mails come pouring in !!
|Hey Moto Man .... It
Works in Netherlands !
This is LEMSTRA RACING in Netherlands. We have tuned two Kawasaki ZX6R's with, 01 works racing kit, adjustable ignition (mapping per 250 revs), and we tuned one with ports like you described at 65% smaller and we went from 110 rear wheel bhp to 115.6!
Thanks and greetings from Alkmaar, Holland
|Hi Freek !!
That's waaay cool that you hi - velocity ported your cylinder head !!
You're the first person to use Power News porting techniques and e-mail your results !! The "out of the box" people will always make the fastest bikes !!
Congratulations & please tell everyone in Netherlands to sign up for Power News !!
|Hey Moto Man .... It
Works in France, Hungary, Norway, Sweden &
First of all: Power News is AMAZING !!!
I wanted to tell you that Norway's Kai Børre Andersen won 3 rounds of the European Supersport Championship !! And he's winning here in Scandinavia too.
Even Valentino Rossi was cheering for him as he crossed the finish line to win in Netherlands !!
His bike seems very fast ... undraftable actually.
His Yamaha R6 engine was built by Jørgen Johnsen of Fast Bikes shop here in Oslo. The rumor is that the intake ports are smaller than original.
Keep up the great Power News series !!
~ Øyvind ( Norway)
|Hi Øyvind !
The rumor is true ! I've been working together with Jørgen to develop smaller ports since 1993. Jørgen's Yamaha R6 engine set-up features intake ports that choke down to 65% of the intake valve diameter.
Jørgen's motors are among the fastest on the planet, and Kai Børre is riding the wheels off the bike ... it's a great combination !!
Please tell everyone in Norway to sign up for Power News !!
Congratulations to Team Veidec's
Kai Børre Andersen
Photo Courtesy of Team Veidec:
|Hey Moto Man .... It
Works in the UK !!
I have read your article on reduction porting with great interest! I have been steadily decreasing the size of the Yamaha R6 port and watching the power steadily rise !
At first the smallest port was 75 % the size of the
inlet valve at the choke point.
I have now gone down to the 65 % you suggested, and got even more power !!
~ Phil (England)
Hi Phil !!
|Hi MotoMan !
Just for your information, I was in Jan Roelof's (Netherlands) workplace a few weeks back and saw that he was filling in the inlet tracts just as you describe in Power News. I saw a couple of R6 heads and a XT660 head with filled in inlet tracts, & some with preparations to do so.
His R6's where measured with the highest top speed at the Philip Island Australia World Supersport race this year.
~ John (Netherlands)
|Hi John !
Thanks for the info ! I always thought that Jan Roelof is one of the best
tuners in the world.
|Hey MotoMan !
A fellow Water Cooled GSXR rider sent me over here to Mototune USA. First I want to say thanks for sharing some of the secrets, Power News has been some great reading.
I have a 1993 GSXR 750 with Stock internals and no porting what so ever, I have added the following bolt ons: WebCams 352 Cams, Keihin 39mm Flatslide Carbs and a Yosh full Race Duplex system. From what others have said I am looking at roughly 125 RWHP Not bad for a 9 year old bike. I would like to hit 130RWHP without a BIG Bore Kit do you think your "reduction porting " will work on an older bike like mine ??
Thank You for your Time !
|Hi Jim !
Yes, smaller ports will work "awesome" on your bike !!
In 1994, Jørgen [the same Jørgen as in the 2nd letter] and I developed the intake ports for Suzuki Norway's Jan Olav Noteng. That year Jan Olav qualified within a couple tenths of a second of Factory Suzuki rider Herve Moneau at a World Superbike race ... with smaller ports.
No one could figure out why that bike was so fast ... now you know !! Wow !!
Please tell everyone in the USA to sign up for Power News !!
I have been reading with interest your work on the high velocity ports I have a zx11 with 1137cc cosworth piston kit, yosh cams, flatslides, etc and last year was making 175 hp.
Over the winter 1 mm oversize inlets valves were fitted, with the ports opened out the same, and compression increased from 12.5-1 to 13.1-1, and I have struggled to 173 hp now.
Have you carried out high velocity port work on the zx11 head, and would you still expect to get the same results ??
|Hi Arthur !
The "problem" with the ZX11 cylinder head, is that it's flow can be increased tremendously over stock. More so than any modern head I've come across. This creates a situation where flow porters get a real adrenaline rush when they hook up the head to the flow bench !
I have full confidence that Power News will put an end to the flow=power idea, which has resulted in 'zillions' of lost horsepower over the years. (where does it all go ??)
I believe that energy isn't lost, it just goes somewhere else. In this
case the adrenaline gain experienced by the
head porter, is approximately equal to the amount of adrenaline loss
the rider experiences when he rides his newly flow-ported bike.
At the beginning of the twentieth century, everybody "knew" that a heavier-than-air machine couldn't possibly fly. It would violate the "laws" of physics.
All of the "experts" said so.
Luckily, there were some who refused to think in the "box" ....
and today we take airplanes for granted !!
Thanks to YOU, the readers
of Power News,
the "experts" are once again being overtaken by
the "out of the box" thinkers !!!
What About 2 Valve Heads ???
I've had tons of e-mails asking if this idea works on car engines, Harley-Davidsons,
and older Japanese engines which use just 1 intake valve.
I can't really say for sure, because I've never high velocity ported a 2 valve head before.
If I were building a 2 valve engine, the curiosity would get me, and I'd just have to go for it !!!
The 65% formula is a rule that works on multi valve heads. With a 2 valve head, I'd first start by reducing the choke point height of the port to 80% of the intake valve. The peak power may not increase, but it could give the midrange power a boost.
This is most likely the dimension of the stock port, so I'd recommend checking it first before removing the cylinder head. Remove the carburetors and compare the height of the port at its tightest point against the intake valve's diameter. (The valve diameter should be listed in the shop manual.)
Please understand that this would be an experiment, as I've never done it myself.
The Ultimate Test !!
Once when I was in Norway, I had an amazing opportunity to
dyno test High Velocity Porting !!
As it turned out, the rider I was helping out had a cylinder head on his engine which was
from the Yamaha R6 that Germany's Jörg Teuchert used in 1999 to win a
World Supersport race !!
The valve seal was fresh, and we had every reason to believe that it represented the cutting edge
of racing technology for 1999.
I just had to whip out my camera
and take a photo of the intake port for you:
As you can see, I was surprised to find out that the ports were bigger than stock !!
I have to admit, I was getting a little scared, seeing as how I was going up against the best in the world !! Mototune easily beat
the Yamaha US Factory Team in Supersport power & speed in America, but now we're talking about World Supersport ...
"The Box" started to close in all around me, and I felt the familiar "fear adrenaline" surge as we drove to the dyno test.
This head was ported by the best in the world, and was a winner on the racetrack. Now I had to face the music !!
My customer would be really mad if we ended up losing power after coming all the way over there !!
But, even worse ....
What if I've told my 8,709 friends who've subscribed to Power News a bunch of hogwash ???
MotoMan was really up against the wall now, with nowhere to run & hide !!!
We got to the dyno facility, and as the engine was warmed up...
Beads of sweat appeared on my forehead !!
This could be a real ugly scene ...
What happened ???
Horsepower & Personal Power
What happens when you decide to high velocity port your cylinder head ???
You can't make that decision without also making some amazing realizations,
all of which increase your personal power:
1) You think out of the box !!
2) Money can't buy everything. (This will change as more professional tuners sign up for Power News)
3) Truth (reality) is often regulated for a variety of reasons.
4) You personally have a lot more power than you may have previously realized.
5) The possibility that there are many other things in this world that are the opposite of what they appear,
but you've got to be able to get out of the box to see it.
6) Information on "the internet" can't automatically be discredited because of the silly "dot-com" phenomenon.
7) Power News does in fact ... ROCK !!
8) Oh yeah, I almost forgot ... your engine will suddenly become really, really fast !!
Think Outside of The Box
Like the many layers of an onion, after breaking out of one box, look hard enough, and you'll find a new one.
Some boxes are built more solidly than others, but with practice, one day you'll find that all the walls will fall quite easily.
For The First Time Ever Seen On
World Wide Media:
" Little Exhaust Ports "
... Of A 126 HP Yamaha R6 !!
This is the work of someone I have a lot of respect for !!
Here's the guy MotoMan calls when I've got motor questions:
I'm talking about none-other than Jørgen Johnsen from Fast Bikes shop in Oslo, Norway !!
was cool enough to let me show you one of the
secrets to his
126 horsepower R6's !
Nope, I didn't come up with this idea ... it's all Jørgen's !!!
[ Applause ]
And now without further ado ...
This is the stock R6 exhaust port size ...
The blue clay represents the area which will be carefully welded up to create supersonic velocity !!
(Aluminum welding must be done a little at a time to
avoid warping the head.)
If the idea is to reduce
exhaust pumping losses, and that means increasing "flow", how can this
possibly work ??
Remember the 8 Phase Article !! Here's a review of the 2 distinct exhaust phases ...
2 EXHAUST PHASES (Exhaust Blowdown / Exhaust Return)
The exhaust must be completely cleared from the cylinder. The only way to accomplish this, is to open the exhaust valves about 30-40 degrees before the bottom of the power stroke, so that the still burning charges pressure can begin to escape out of the cylinder. If the power phase were allowed to continue to the bottom of the piston stroke, the piston would have to work hard to push against the high pressure created by the still burning (and still expanding) gasses during the upward exhaust stroke. Instead, some of it's own pressure is used to blow itself out of the cylinder while the piston is still on the down stroke.
By the time the piston reverses direction in the exhaust return phase, the excess pressure is gone. If the exhaust silencer is positioned as shown in the Dynamic Horsepower newsletter, there will be a slight vacuum which will actually pull the piston up !!
The "textbook 4 stroke" had positive pressure during the exhaust return phase, whereas I'm saying there is vacuum !!
Which one makes more sense ??
It turns out that when you decrease the
area of the exhaust port to the point where the flow
exceeds the speed of sound, the amount of energy necessary to clear the cylinder of
exhaust gasses is almost zero !! (so much for the supersonic nozzle "problem" !!)
By placing the port's smallest cross section, or "choke point", below the valve seat,
the flow's maximum velocity pulls the exhaust gasses out after the bottom of the power stroke.
When this happens, the piston is actually pulled up for the exhaust return stroke !!!
It's not 100% "free power", because the energy comes from the last of the expanding gasses from the power stroke. But, it turns out that this tradeoff of energy results in more power gained through using the gasses to pull out the exhaust than to use them for a longer power phase.
In other words, the power stroke end gasses are being used to
make the exhaust stroke effectively into a mini 2nd "power stroke" !!!
Call it the "Power Upstroke" !!!
On the flow bench, these "Mach 1"
exhaust ports really "scream" and ear plugs are required
Superbike High School !!
A couple of months ago, at Northern California's McKinleyville High School,
I helped auto shop teacher Mr. Dave Backman teach Superbike Engine Technology
to his students !!
Power News reader and AFM racer JD Grow told his former high auto shop teacher about Power News. Dave liked it so much that I was invited to do a seminar for his class !!
Learning to Think Out of The Box
McKinleyville High School's auto class ROCKS !!
A Power News "Report Card" From Mr. Dave Backman !!
Your analytical mind, your natural inquisitiveness of things mechanical, coupled
with your practical and logical thought processes, has developed you into an
“outside the box” thinker. I cannot thank
you enough for your visit to my class, I am looking forward to your return.
is the best !! "
Mototune USA 's
Rocks !!! "
The Power Behind Power News ... Budweiser !!
P O W E R V O T
World Supersport VS Power News
Who Do You Think Won The Test ??
Learn How to Do it Yourself:
Smaller Intake Ports Gain 7 % More Power