Just curious, Who has ported their head?

[iceman.kcmo]

So i have a stock Cracked head sitting around. Thinking about playing around with it. Has anybody ported their head? I know there is some work to be done in there. I saw this site and thought it was pretty neat.

http://www.eurospares.com/ex2501.htm


and kinda this thread

http://www.ninjette.org/forums/showthread.php?t=9698


I have kinda been toying around with pulling the head and jugs off the bike and re-ringing it, but it probally doesn't need it. Still runs real good. Just looking to get a little more toothpaste out of the tube if you know what im saying.

[Racer x]

I need to get it done . I am having an engine built it will have extensive head work .
From what I read looking into it for doing it myself. Everything I read said don't . Other than obvious flashing .I would be surprised to find any in a motorcycle engine. But it could happen.

One thing I found about the new head is the ports are very small. So the best thing to do is go with bigger valves. Then port the head . There is a hole for the clean air system in the exhaust port that will need to be welded shut .

With out a flow bench there is no way you can tell if you cause more harm than good . Air velocity is the thing .Not volume.So shaping is critical . So I will have to pay some one to do it.

[iceman.kcmo]

What about Grinding the valve seats to the "margin"? A bigger valve is just something bigger for the air to hit before it gets to the chamber. My uncle builds and races bikes and that is what he does. He doesn't put bigger valves in it. The valves already overhang the cylinder a little. That would just be more shrouding.

I dont plan on makeing anything bigger. Just work on the floor on the intake side, and the bowls. If i remember correct, the roof of the exhaust side leaves a little to be desired. But i mainly want to work on the bowls.

Did you see this picture? its on one of the websites i listed. good reading there.



This will get alot straighter path to the chambers.

[Racer x]

WOOO . I want to see more of that.

[2WheelGuy]

I have a ported head on one of my pre-gen race bikes. The work was done by Mike Norman at G-force. He is one of the most knowledgeable EX250 engine builders. He built most of the fast bikes out here. I remember him saying that the ports are very restrictive and proper porting yields the biggest gains on these motors. I don't believe he used over sized valves. I may even have a spare G-force ported head in my spares collection that will come out when I do my spring cleaning.

[Racer x]

I was speaking of over sizing the valves on new engines. 1mm is what I have seen. My over all point is I don't think it is something you can just do yourself. But from what I have heard it is worth 4 to6 hp when done properly.

I would love to see some close up photos of a professionally ported head .

[iceman.kcmo]

Originally Posted by 2WheelGuy

I have a ported head on one of my pre-gen race bikes. The work was done by Mike Norman at G-force. He is one of the most knowledgeable EX250 engine builders. He built most of the fast bikes out here. I remember him saying that the ports are very restrictive and proper porting yields the biggest gains on these motors. I don't believe he used over sized valves. I may even have a spare G-force ported head in my spares collection that will come out when I do my spring cleaning.

If you do decied to sell that head, Let me know. I will be interested. Can you say where the mains spots it was worked over at?

Im not planning on putting bigger valves in, I just want to work on the ports.