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Speed's Best Friend
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Discussion Starter #1
Im looking to buy a ported head, I find several descriptions on how there ported. I heard 5-angle, CNC. Whats the difference, whats the best?

Also, I am planning a very mild trail build, but it has been recommended to me to look for a +2 port. Apparently they cost the same and will work about the same with a mild build. However I will have more flow if i choose to add a larger TB and bigger piston. Does that make sense? Are there any draw backs?
 

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Im looking to buy a ported head, I find several descriptions on how there ported. I heard 5-angle, CNC. Whats the difference, whats the best?

Also, I am planning a very mild trail build, but it has been recommended to me to look for a +2 port. Apparently they cost the same and will work about the same with a mild build. However I will have more flow if i choose to add a larger TB and bigger piston. Does that make sense? Are there any draw backs?
5 angle may be refering to the number of angles used when reworking the valve seats in the head.

CNC means = computer numerically controlled. What that is, is after a port has been reworked and it's design/shape proven it will be mapped/digitized into a program so the CNC machine can cut/reproduce exactly each and every time.

The +1 or +2 you're hearing refers to the valve size. Typical thinking would say a +2 is too big on a mild trail build, especially on a ss/sb. the valves are too close and become crowded to the cylinder wall at lift, which reduces overall flow. On a 105+ cylinder bore they are less crowded and then the benefit of the bigger valve helps. You can't just have big valves tho, you need all the other mods to allow them to work to their potential.
 

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Speed's Best Friend
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Discussion Starter #3
For purely financial reasons, Im going to get the head, cam and a sb 11:1 piston now. Then plann to switch to a 105.5 cylinder and 11:1 piston with a 54mm TB later. So does it make sence to get the +2 head now, or will the crowding hamper my performance with the stock bore piston now?
 

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For purely financial reasons, Im going to get the head, cam and a sb 11:1 piston now. Then plann to switch to a 105.5 cylinder and 11:1 piston with a 54mm TB later. So does it make sence to get the +2 head now, or will the crowding hamper my performance with the stock bore piston now?
I run the 660 motor, I've ported 660s and worked on the 450 heads also. I was porting in the early 1980's when porting was very important because heads came from the factory flowing less then 70% of their potential. The heads we see today out of Japan are already flowing at over 90% of their potential and designed to work in the entire RPM range. If you wish to add power by opening up the head you need to take baby steps and define what level rider you are and what type of riding you plan on doing. The +2 valves and HV porting will give you a motor that screams at 9000-10000 RPM (perfect for drag racing but terrible for woods racing) but less to desire at 3500 RPM; you will notice the loss at 3500 so be prepared if that is an RPM range you're often riding at. +2 valves and HV porting will require more intake volume and exhaust volume along with a cam that can push and pull the flow at High RPMs. This is not a Low RPM consideration so as I said before, take baby steps. You're on the right track with the 105.5 and 11:1 for more torque and big HP numbers. You can add head work as you adjust to the new found power and define you horsepower objectives.
 

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Speed's Best Friend
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Discussion Starter #5
I run the 660 motor, I've ported 660s and worked on the 450 heads also. I was porting in the early 1980's when porting was very important because heads came from the factory flowing less then 70% of their potential. The heads we see today out of Japan are already flowing at over 90% of their potential and designed to work in the entire RPM range. If you wish to add power by opening up the head you need to take baby steps and define what level rider you are and what type of riding you plan on doing. The +2 valves and HV porting will give you a motor that screams at 9000-10000 RPM (perfect for drag racing but terrible for woods racing) but less to desire at 3500 RPM; you will notice the loss at 3500 so be prepared if that is an RPM range you're often riding at. +2 valves and HV porting will require more intake volume and exhaust volume along with a cam that can push and pull the flow at High RPMs. This is not a Low RPM consideration so as I said before, take baby steps. You're on the right track with the 105.5 and 11:1 for more torque and big HP numbers. You can add head work as you adjust to the new found power and define you horsepower objectives.
Thanks, that helps. I have no intention of Drag racing and spend very little time at 9000 rpms. I soley ride trails and am looking for more power in the mid rpm, top of 3rd, middle of 4th. Ive been taking my time building the quad the right part at a time. I already have a decent intake, +3 TB, DMC duals, Dynatech ignition and a PC5 to pull it all together. So the next step is the Head work and cam. The big bore may not be till next season. I also plan to do a clutch and HD springs when i do the head, even though its probably not necessary.

Can you elaborate on the different methods used to port the heads and what I should look for when buying one?
 

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Thanks, that helps. I have no intention of Drag racing and spend very little time at 9000 rpms. I soley ride trails and am looking for more power in the mid rpm, top of 3rd, middle of 4th. Ive been taking my time building the quad the right part at a time. I already have a decent intake, +3 TB, DMC duals, Dynatech ignition and a PC5 to pull it all together. So the next step is the Head work and cam. The big bore may not be till next season. I also plan to do a clutch and HD springs when i do the head, even though its probably not necessary.

Can you elaborate on the different methods used to port the heads and what I should look for when buying one?
I have never seen or used a CNC ported head, however, unless you're shooting for a record holding bike or doing professionally heads up drag racing I really can't see why a CNC machined replication of a "hand massaged" head wouldn't fit your needs. Regarding the throats, generally when the throats are cut from a head the person porting/selling you the head will ask what your intentions are and suggest a percent-over that will fit your riding style. (e.g. 90-95% cut throats would be full drag racing application). When they cut the throat from a head your calculating a percentage of the diameter of the valve you are planning on running and matching (cutting) that to the throat which is the area around the seat as the air enters the combustion chamber (e.g. a 30mm valve at 90% would be 27mm, so you would cut the stock diameter throat to 27mm) This measure is critical in producing a fire breathing monster but also may produce a hunk of aluminum that will fall on it's face due to the loss of fuel/air velocity into the combustion chamber. Again, define what RPM range you plan on riding most and be careful when you over size valves and cut throats. I wouldn't go over 85% for a trail riding, hill climbing, rough terrain bike. The same logic applies to the cam selection, look carefully at duration, overlap and when the intake valve closes after BDC if you want a bike that performs well in tight woods and rough terrain. Don't build a head that's bigger than your cam or you may be sadly disappointed.
 

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Speed's Best Friend
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Discussion Starter #7
I have never seen or used a CNC ported head, however, unless you're shooting for a record holding bike or doing professionally heads up drag racing I really can't see why a CNC machined replication of a "hand massaged" head wouldn't fit your needs. Regarding the throats, generally when the throats are cut from a head the person porting/selling you the head will ask what your intentions are and suggest a percent-over that will fit your riding style. (e.g. 90-95% cut throats would be full drag racing application). When they cut the throat from a head your calculating a percentage of the diameter of the valve you are planning on running and matching (cutting) that to the throat which is the area around the seat as the air enters the combustion chamber (e.g. a 30mm valve at 90% would be 27mm, so you would cut the stock diameter throat to 27mm) This measure is critical in producing a fire breathing monster but also may produce a hunk of aluminum that will fall on it's face due to the loss of fuel/air velocity into the combustion chamber. Again, define what RPM range you plan on riding most and be careful when you over size valves and cut throats. I wouldn't go over 85% for a trail riding, hill climbing, rough terrain bike. The same logic applies to the cam selection, look carefully at duration, overlap and when the intake valve closes after BDC if you want a bike that performs well in tight woods and rough terrain. Don't build a head that's bigger than your cam or you may be sadly disappointed.
Got it, thanks for your help.
 

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A +2 ported cylinder head set up for a 54mm TB will loose no power down low. You will however gain a ton up past 5500:
Baselined before the swap from 44mm TB to 54mm so its back to back test:



Driveability:
 

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Speed's Best Friend
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Discussion Starter #9
Thats very interesting. So do you recommend a +2 reguardless? I remember when I bought my +3 TB. I asked the builder if the +3 was a significant difference over the +2. I was told everyone gets a +3 reguardless of what they order. It was cheeper for the builder that way, even though he typically charged more for the +3.

Do you have any recomendations on the different methods to port a head. It seems to me that the CNC would be more consistant, where something else may depend on if the guy got laid the night before. I can also see that it may not matter as much for the build Im looking for.
 

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the biggest benefit to cnc heads is the time it saves to create it. Its much easier to change a cnc head that is almost dont than starting fresh. You get the repeatably factor as well and you can do some smoothing in the programming. i would say most people probably have between 6-15 hours in hand porting a head depending on what is done where you could have a cnc head and save 15 hours and the builder spends some $$ it just depends on how people want to do things
 

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A +2 ported cylinder head set up for a 54mm TB will loose no power down low. You will however gain a ton up past 5500:
Baselined before the swap from 44mm TB to 54mm so its back to back test:



Driveability:
I'm having trouble reading your dyno graph and understanding which lines represent which bike? Bottom dotted line is Torque...for 54mmTB? and top solid line is what? it doesn't peak at 81 HP, closer to the 72.9 number. Sorry for the misunderstanding on the graph but I am genuinely interested in seeing the data.

If you are going to show dyno numbers and suggest the benefits of the larger ports and TB diameters please elaborate on the cam used in that motor and what compression piston was required to off-set the intake valve closing beyond 60 degrees after BDC. He's building a bike to ride trails in the Appalachian mountains, therefore, I advised him accordingly.
 

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Speed's Best Friend
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Discussion Starter #13
I'm having trouble reading your dyno graph and understanding which lines represent which bike? Bottom dotted line is Torque...for 54mmTB? and top solid line is what? it doesn't peak at 81 HP, closer to the 72.9 number. Sorry for the misunderstanding on the graph but I am genuinely interested in seeing the data.

If you are going to show dyno numbers and suggest the benefits of the larger ports and TB diameters please elaborate on the cam used in that motor and what compression piston was required to off-set the intake valve closing beyond 60 degrees after BDC. He's building a bike to ride trails in the Appalachian mountains, therefore, I advised him accordingly.
I was reading the graph as the dotted lines are torque and the solid HP, the lighter lines being the +2 head. It was the head that was switched, not the TB? So max HP is at 80+. I would be interested to know what cam and piston were used. I dont think i need anywhere near 80hp, just interested.
 

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Speed's Best Friend
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Discussion Starter #14
the biggest benefit to cnc heads is the time it saves to create it. Its much easier to change a cnc head that is almost dont than starting fresh. You get the repeatably factor as well and you can do some smoothing in the programming. i would say most people probably have between 6-15 hours in hand porting a head depending on what is done where you could have a cnc head and save 15 hours and the builder spends some $$ it just depends on how people want to do things
Eric,

Im glad you chimmed in since you'll be the one installing what ever i decide to get. I sent you an email awhile ago, just after you dynoed my quad. Ive decided I couldnt foot the cost of the complete build at once. Im going to do it in stages, starting with porting, valves and springs, cam and SB 11:1 piston this spring and 734, better intake and clutch this fall.
 

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I was reading the graph as the dotted lines are torque and the solid HP, the lighter lines being the +2 head. It was the head that was switched, not the TB? So max HP is at 80+. I would be interested to know what cam and piston were used. I dont think i need anywhere near 80hp, just interested.
The lighter lines didn't show up on my computer screen. I copied the image to photoshop and reduced the light then added contrast and now I see the light lines. I'll speak for myself only and say I have not found a HV head and high lift long duration cam build that works in the woods on a 660 motor. If you're racing tight trails with your buddies you won't have the response out of the tight 90 degree turns (2000 - 3000 RPM off throttle on again) and up rough steep hills as with the Lower RPM motors. Fuel injection may be a different animal, let me know how it works out.
 

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Speed's Best Friend
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Discussion Starter #16
The lighter lines didn't show up on my computer screen. I copied the image to photoshop and reduced the light then added contrast and now I see the light lines. I'll speak for myself only and say I have not found a HV head and high lift long duration cam build that works in the woods on a 660 motor. If you're racing tight trails with your buddies you won't have the response out of the tight 90 degree turns (2000 - 3000 RPM off throttle on again) and up rough steep hills as with the Lower RPM motors. Fuel injection may be a different animal, let me know how it works out.
I really appreciate your input. Im sure there are different circumstances for everything.
 

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If it's too loud your too old
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A +2 ported cylinder head set up for a 54mm TB will loose no power down low. You will however gain a ton up past 5500:
Baselined before the swap from 44mm TB to 54mm so its back to back test:



Driveability:
8.5HP is a nice gain for just a TB swap! If I'm reading this right on this set up just swapping from a stock TB to a 54mm TB gained 8.5HP right?
 

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Speed's Best Friend
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Discussion Starter #18
Yeah, i originally read that wrong. The debate was over a power loss in the lower range when going to a +2 head. This shows the differences in TB. Still cool though, i would like to know what piston and cam. The 54 TB is on the list.
 

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This build has the HDD5050 cam which is a short duration/high lift cam. I posted to show that the build has over 40ftlbs of torque at 3000rpm with a +2 port with or without a 54mm TB(and out of a 686).
 
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