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Author Topic: Hi-velocity porting  (Read 1504 times)

Offline trunkbuster

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Hi-velocity porting
« on: December 07, 2014, 05:17:36 PM »
Well, still plugging away at my track bike when I can. I wanted to show what I'm doing to my head :bmp: This was supposed to be part of the track bike post but it came up separately after I got logged out and logged back in...  Anyway, I reduced the intake port size to create a "choke point" for the incoming air/fuel charge. What that does is similar to what happens when you pinch the end of a garden hose, the water flows faster and with more force. The difference, though, is that instead of the pressure coming from a "push" it's coming from the pull of the piston's intake stroke. I didn't come up with this idea, I'm just relating it in this thread in case someone else wants to do it. 
  I recommend this mod for bikes used for road racing or other events where the throttle openings vary along the entire r.p.m. range. The result is a more linear power curve; when you twist the throttle the power tracks right along with it instead of dipping or tapering off. Torque is also increased.  This mod would hinder a bike used mainly for W.O.T. activities due to the extra air intake needed at the higher r.p.m.s.  This is the second time I've done this mod, the first was on the first Hayabusa I built and the result was extremely improved acceleration up through the entire r.p.m range! I posted a few pictures back then but they were too small, I didn't explain what I did either.
  Okay. To start off you'll need to completely disassemble the cylinder head and clean and degrease it thoroughly.  If you're a DIYr I'm assuming you already have basic hand tools and some mechanical know-how.
Some special tools you'll need are:
> A Dremmel tool
> 0-1" and 1-2" micrometers or a Vernier caliper
> a pack of 60 grit Dremmel sanding drums
> a "T" gauge set
> one or two sticks of modeling clay
> a few tongue depressors
And last but most important, JB Weld to build up the intake ports.
The intakes will have to be roughened in order for the bonding material to adhere.  Use the Dremmel with a 60 grit sanding drum and come in from the valve side to roughen the bottom area of the port about a 1/4 of an inch before the intake valve opening.  Be very careful not to damage the valve seat! To be on the safe side, stop and start the tool after inserting in the port.
  Clean out the debris and wipe the surface with electric contact cleaner or denatured alcohol.  Once you've got the head prepared you'll need to measure one of the intake valves to calculate how far to shrink the port down.  The "magic" number is 30% smaller, or the recommended 65% of the valve size.  To find that out, measure the valve diameter:


Next, take your measurement and multiply it by .33. Subtract your result from the initial valve measurement.
The formula is simple: Valve dia. - (valve dia. X .33)= "New" port height OR Valve dia. X .654= Choke point height
You now have the measurement you need to transfer to your "T" gauge:


« Last Edit: December 07, 2014, 08:00:50 PM by trunkbuster »
2003 Katana 7/12: Daily Rider
2006 Busa: "Thing 3", 1430+cc weekend bike
Suzuki GSXR 750 (multiple years): Track bike
Do, Try, or Die!

Offline trunkbuster

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Re: Hi-velocity porting
« Reply #1 on: December 07, 2014, 05:39:10 PM »
Get the modeling clay ready and start making balls slightly larger than the diameter of the intake valve. Once you've made one make sure all the others you make are the same size as the first. Once you've got your balls in hand :? Insert them, one at a time, about half way into the valve seat area. Make sure each one is inserted about the same depth. What you're doing is setting up the base of the choke point for the JB Weld. It will look something like this when you're done:


Break out the JB Weld, a clean Phillips screwdriver, tongue depressor, and something to mix the stuff on:


Position the head so that the bottom of the ports are nearly horizontal to the work surface but still pointing slightly downward. The angle will determine how much surface area is covered and also how much material you'll have to use to build them up.


Mix the epoxy per tube instructions and then roll the mixture onto the clean tip of the screwdriver.


While still rolling the screwdriver, insert it into the throttlebody side all the way down to the clay, but don't poke into it. What you'll want to do now is roll the screwdriver clockwise against the left side and counter-clockwise against the right side of each port then roll the tip as you retract it. This rolls the epoxy back onto itself. Once it's rolled off repeat until you've built it up to the point of near closure, but NOT completely. It will look like this:




« Last Edit: December 07, 2014, 07:33:02 PM by trunkbuster »
2003 Katana 7/12: Daily Rider
2006 Busa: "Thing 3", 1430+cc weekend bike
Suzuki GSXR 750 (multiple years): Track bike
Do, Try, or Die!

Offline MJ Williams

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Re: Hi-velocity porting
« Reply #2 on: December 07, 2014, 05:52:55 PM »
Do you have objective acceleration measurements such as "before the mod it took 2 seconds to go from 100 to 150 hp and after it took 1.75 seconds"? Also what was the difference in torque. Thank you
Have a Harley, spent lots of money on it, thought I had a fast motorcycle, bought a Busa, realized all I had was a fast Harley, not a fast motorcycle!

Offline trunkbuster

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Re: Hi-velocity porting
« Reply #3 on: December 07, 2014, 05:54:30 PM »
Give the epoxy at least 48 hours to set then remove all of the clay. At this point you are now ready to begin shaping the epoxy to your pre-measured dimensions you set your "T" gauge to earlier.


As you're shaping the choke point ensure it is the same width as the port but don't take too much material out at one time. Start with the sanding drum a little at a time and measure with the T gauge between each pass so as not to go over the height you need.  When you get close use a strip of 120 grit sand paper on your finger to get it where you need it. It should look something like this when you're done:




Once complete, wash the head off again and use pipe cleaner to clean out the valve guides. Reassemble your motor, put it back in your bike and you are ready to rock and roll :bike:  While your engine is apart, though, you can do things like adding adjustable cam sprockets to add even more umph.
2003 Katana 7/12: Daily Rider
2006 Busa: "Thing 3", 1430+cc weekend bike
Suzuki GSXR 750 (multiple years): Track bike
Do, Try, or Die!

Offline trunkbuster

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Re: Hi-velocity porting
« Reply #4 on: December 07, 2014, 06:04:13 PM »
Do you have objective acceleration measurements such as "before the mod it took 2 seconds to go from 100 to 150 hp and after it took 1.75 seconds"? Also what was the difference in torque. Thank you
Hi! I wish I did! That would make this post complete. I did this to my bike about 4 years ago. Here is the site I got the info from: http://www.mototuneusa.com/think_fast.htm The performance difference I felt after I did it to my own bike was like night and day. If I had the funds I would take it to the dyno around the corner here and get the data myself 8)
« Last Edit: December 07, 2014, 06:39:27 PM by trunkbuster »
2003 Katana 7/12: Daily Rider
2006 Busa: "Thing 3", 1430+cc weekend bike
Suzuki GSXR 750 (multiple years): Track bike
Do, Try, or Die!

Offline trunkbuster

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Re: Hi-velocity porting
« Reply #5 on: December 07, 2014, 07:02:41 PM »
 I got the idea from http://www.mototuneusa.com/power_news_--_homework.htm  This link gives more detailed instructions and the theory behind why it works. This is the link to part 2: http://www.mototuneusa.com/power_news_--_the_2007_superbike.htm You may want to bookmark that site for future reference.
 
« Last Edit: December 07, 2014, 07:19:43 PM by trunkbuster »
2003 Katana 7/12: Daily Rider
2006 Busa: "Thing 3", 1430+cc weekend bike
Suzuki GSXR 750 (multiple years): Track bike
Do, Try, or Die!