I had a Doctor Appt this afternoon which resulted in some additional errands.
Gators playing Roundball again tonight so there will be no smoke show until tomorrow.
Again I imagine it will anti-climatic for most.
I do think that there are some that will be interested in the attached Video as it is directly related
I made this video back when I started doing this...
It's all about discovery af facts vs myths.
I do all my testing with an open mind, without any preconcieved ideals that I need to prove.
The consistent repeatable tests don't lie, the numbers are what they are always.
My only objective is and always has been to make certain the process is driven by the actual data.
This video is simply an overview of how I went about doing my Pocket Port and giving a glance in what is involved.
Some things that I have learned from testing my Pocket Port as well as gggGary's Madness Pocket Port...
The cut on the left side at the opening of the port is an intentional enginered design that I call Vaning.
That is because it's intent is to provide a slight constriction to accelerate the air just prior to the swelling within the port.
In doing so it also does a great deal to aid in creating Swirl which is an important ingredient
for Maximum burning of the fuel mixture and increased power. Something that should not be overlooked.
The Increased Velocity equates to Kinetic Energy which pushes against the air slowed by the opening
or swelling section of the port creating a High PRESSURE Zone right before the MSCA (Minimal Cross Sectional Area).
This is what creates the force for the inertia not only while the valve is opened but even more importantly
while it is closed to maximize the power of the mixture to pack the cylinder once the valve once again opens.
My testing as evidenced within this thread as well as the testing on my own Pocket Port,
make it obvious that there are Little to NO gains to be had from doing this.
(Disregarding highly built race motors, this dicussion is about street/ hot street set ups).
The port is already too big. Making it bigger only slows the Ultra important VELOCITY!
The Port is so cavernous that streamlining the air flow by removing these casting flaws produces no gains.
This is due to the Port's inefficiency. An example of this is the Flowball testing.
I can place a 6.3mm (1/4") flowball into the stock port virtually anywhere (excepting the SST) without disrupting flow.
Clearly these casting flaws are nowhere near that, making it obvious that they will have even less effect.
The fact that the XS650 ports are too large is something that has repeatedly been mentioned within this forum by a multitude of members.
The fact is that the Stock head already flows enough CFM. The testing is very clear and irrefutable.
To achieve any gains from Pocket Porting, there has to be other work done.
The cavernous volume needs to be shrunk to make the port EFFICIENT!
In an Efficient Port, I can place a 4mm flowball anywhere within the port and see a disruption.
My smallest flowball (1/8) of an inch causes disruption in nearly 80% of the port.
In a Stock Port I can get disruption with a 1/4" flowball in less than 10% of the port (SST just before the valve mainly)
The remedy for making the Ports flow better is in REDUCING the Volume!
This is best done by building up the floor, Decreasing Volume which Increases VELOCITY.
That also has the added benefit of making it possible to recreate the SST's profile
allowing us to slow and or direct the flow over this critical area.
Proper shaping of the raised floor also allows for directing the air towards the roof,
providing gains in Velocity throughout that region as well while maintaing CFM.
The other way to make gains in the XS650 Port is Valve/Valve Seat work.
This is where any gains (or losses) at low lift are created. There is a lot to be gained in this critical area.
The Improved CFMs gained from this area are every bit as Important as those made anywhere else within the port.
Certainly one needs to exercise caution if DIY. There is the Potential of flowing it too fast at the low lifts if one gets too slick.
That is if the rest of the Port is Efficient. A well done 3 angle on a Stock Head has shown substantial improvement in the Total CFM
However on a Highly Efficient Port that "extra" speed can become disruptive.
That is why I ended up placing a simple 45* angle on the D45 F head. Indeed that is what the "45" Stands for.
I absolutely DO Recommend placing a 30* "Back cut" on both the Intake and Exhaust Valves regardless.
Provides a nice bump at the low lifts for Velocity as well as CFM.
The Valve and Port work together, so there is no one size fits all way of doing it.
This stuff is VERY difficult to do and get right without being able to test.
A 2mm difference can cost you 3% or more ((4-5 Cfm) as seen in the attached diagram.
Again.. as always, do what you will with the information,
"You can lead a horse to water, but you can't make them drink".
The Video (which includes the 3 angle Valve job) and some pics attached....
... whatever it takes, get the oxide layer off, clean with acetone and immediately bond it in place. That'll give you the best adhesion you'll ever achieve.
