What do I have here?

[Zakradu398]

I bought a drag ported head and I know nothing about it. I know valves are bigger and not stock, along with springs and retainers. Anyone got a clue? http://m148.photobucket.com/albumview/albums/zakrad_u/Mobile%20Uploads/IMG_0945_zps0b5025bc.jpg.html?action=view&current=IMG_0945_zps0b5025bc.jpg

[DragonGunner]

Well if its ported is going to give you better flow and hp....not sure what a drag port is, but my guess is its ported on the exhaust side as well as the intake. Intake side is good, but too much out of the exhaust can actually hurt it unless its a really big bore built for just dragging. Most MX and XC ports should only have a intake port and at best a clean up on the exhaust side. Too much flow can cut back on your back pressure, with out proper back pressure even on 4 strokes it will cut power.

[Zakradu398]

Well if its ported is going to give you better flow and hp....not sure what a drag port is, but my guess is its ported on the exhaust side as well as the intake. Intake side is good, but too much out of the exhaust can actually hurt it unless its a really big bore built for just dragging. Most MX and XC ports should only have a intake port and at best a clean up on the exhaust side. Too much flow can cut back on your back pressure, with out proper back pressure even on 4 strokes it will cut power.

Looks stock on exhaust, possibly a clean up I got a bit of carbon build up inside but not sure how to get it out without messing up valve guides. The intake side looks good and even , the bridge is sharp enough to cut your finger, the outside of the intake looks a little bigger than stock but the rubber boot is also slightly ported.
I will get a pic

[Zakradu398]

http://m148.photobucket.com/albumview/albums/zakrad_u/Mobile%20Uploads/IMG_0937_zps26973d3e.jpg.html?action=view&current=IMG_0937_zps26973d3e.jpg

[Zakradu398]

http://i148.photobucket.com/albums/s31/zakrad_u/Mobile%20Uploads/IMG_0937_zps26973d3e.jpg (http://s148.photobucket.com/user/zakrad_u/media/Mobile%20Uploads/IMG_0937_zps26973d3e.jpg.html)

http://i148.photobucket.com/albums/s31/zakrad_u/Mobile%20Uploads/IMG_0945_zps0b5025bc.jpg (http://s148.photobucket.com/user/zakrad_u/media/Mobile%20Uploads/IMG_0945_zps0b5025bc.jpg.html)








I plan on putting in new valve seals and lapping.

[JOHNDOE83]

nice port job!

A drag port is the biggest with the most flow for the most HP.

Back pressure in a 4 stroke is irrelevant, backpressure will actually lower your hp and create a muffler in a 4 stroke.

Back pressure in a 2 stroke pipe matters, not in a 4 stroke.

[Zakradu398]

nice port job!

A drag port is the biggest with the most flow for the most HP.

Back pressure in a 4 stroke is irrelevant, backpressure will actually lower your hp and create a muffler in a 4 stroke.

Back pressure in a 2 stroke pipe matters, not in a 4 stroke.

I understand what porting is but thanks :p got any clue about those valves or springs?

Also, I talked to the previous owner and he said valves are bigger than stock, that is all he knows.


Curious if it's possible to guesstimate HP, it has 11:1 wiseco, stage 2 HC, this head, powerbomb header, yoshi shorty silencer, no lid, uni , and stock carb

[chronicsmoke]

I understand what porting is but thanks :p got any clue about those valves or springs?

Also, I talked to the previous owner and he said valves are bigger than stock, that is all he knows.


Curious if it's possible to guesstimate HP, it has 11:1 wiseco, stage 2 HC, this head, powerbomb header, yoshi shorty silencer, no lid, uni , and stock carb

What did you pick this up for if you don't mind me asking?

[Zakradu398]

What did you pick this up for if you don't mind me asking?

Stock head is messed up/ stripped bolts. This seemed like a good deal as long as head was in good shape which it is. I snagged this for $150 shipped.

[Zakradu398]

What piston will I need , I'm assuming my 11:1 won't have clearance

[Zakradu398]

The clearance is 1.5" intake and 1 3/100" exhaust I believe. Now I need to find out how big my valves are.

[Zakradu398]

1.5" intake and 1.3" exhaust so I should be good with up to 38.1mm intake and 33.1mm exhaust valves I believe.

[81dasher81]

oversize valves don't really do alot, i talked to a few guys who raced pro tt, they all say they dont go bigger on valves, you barely get any more power from them.. once in a while they'll go bigger on intake, but like i said they dont help you out alot.. a nice port job will help you more than anything.. which you have

[Thumpin440ex]

Kibble White springs maybe ? Port work looks decent. All about how much ya can get in and out with out hurting the scavenge effect of the exhaust.. Your prob in the mid to high 30 hp range. A 450 carb would help in both throttle response and mid to top HP.

John

[DragonGunner]

nice port job!

A drag port is the biggest with the most flow for the most HP.

Back pressure in a 4 stroke is irrelevant, backpressure will actually lower your hp and create a muffler in a 4 stroke.

Back pressure in a 2 stroke pipe matters, not in a 4 stroke.


Sorry but thats not true, I've talked with CT racing and another builder on this, to much flow and not enough back pressure on 4 strokes can hurt. I found this out by talking to them before my port job on the EX. I also talked to the KTM guru out west that is one if not the best porter about my 2002 KTM 4 stroke I was puttin in a quad frame, Seems the 2000 to 2002 KTM 520 are faster than the 2003 and up.....why? Because KTM put more flow into the head, mainly the exhaust side, more flow going out with less back pressure hurt the motor.

[Thumpin440ex]

Scavenging and back pressure is often refereed as the same thing, but it isn't. Gunner has a point.. You do need some back pressure in order to aid in scavenging. Thats why you see alot of heads on cars have a D style port in the exhaust port, also why companies sell epoxy to build the exhaust ports up at the lip. It is a fine line on how to tune the exhaust. All about that scavenge :D

John

[JOHNDOE83]

Sorry but thats not true, I've talked with CT racing and another builder on this, to much flow and not enough back pressure on 4 strokes can hurt. I found this out by talking to them before my port job on the EX. I also talked to the KTM guru out west that is one if not the best porter about my 2002 KTM 4 stroke I was puttin in a quad frame, Seems the 2000 to 2002 KTM 520 are faster than the 2003 and up.....why? Because KTM put more flow into the head, mainly the exhaust side, more flow going out with less back pressure hurt the motor.

Yes but the back pressure your speaking of is in the cylinder created by the valves and cam type, the port has nothing to do with that.

A clean up port job is just that, cleaned up. A mild port is cleaned up and sharpend a bit. A drag port is when everything is shaved down and sharpened to the thinest wall diameter possible for max flow.

Maybe I misunderstood what back pressure we were discussing, but in the 4 stroke world back pressure cannot be made with ports, only by valves, cams, pistons.