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11-14 Exhaust Porting

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I have a 13 KX250ZDF and I have decided to try my hand at porting.  This bike already has widened intake ports (stock), so I will just smooth and knife-edge the divider for better flow around it on the intake side.  The exhaust port is what needs a lot of work.  I would like to see some photos of exhaust porting, and intake if anyone has good examples (especially 13 model intake port job).  I have searched and found a few things.  My '11 head porting pics are on here, but I know what that looks like, and I'd like to see some other work.  Thanks in advance.

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how much experience do you have doing porting ?

It is possible to "Take Away" some power if done improperly.

Just a suggestion, The guys who design these engines are pretty smart and use flow benches and dyno's to determine air / fuel charge flow.

Due to Mass production, some of the "trueness" of the porting suffers. So I usually look for the imperfections in the castings and take them out. Remember on the intake side, you want a slightly rough finish to help the fuel / air charge "Tumble" and achieve better mixture.

on the exhaust side, you can remove the flaws in the castings and smooth port and polish this side. It looks cool and also helps keep the carbon from building up in the port.

I would have to say, where you will make the most improvement on flow is the area where they install the valve seat. There is usually a overhang of material or gap where they meet. This area should be blended perfectly, if material is missing and there is a void below the seat, I will use some aluminum epoxy and fill those gaps and blend the epoxy to make a smooth transition.

I would not expect too much from the porting either ,it can help a bit but to get real HP out of the motor you are going to have to get oversized valves and seats, and aftermarket cams, and their running gear.

Al

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I don't know why people think they are Mitch Payton.....leave these Fuel injection bikes stock, meaning pistons,

cams, whatever and just throw a decent pipe on it if you need it.   if you are not a pro, you don't need

the tiny bit extra power and worry about reliability.  Faster guys where I race and practice would trounce

most of us on a clapped out 04' yz250f..........learn to deal with it.

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I don't know why people think they are Mitch Payton.....leave these Fuel injection bikes stock, meaning pistons,

cams, whatever and just throw a decent pipe on it if you need it.   if you are not a pro, you don't need

the tiny bit extra power and worry about reliability.  Faster guys where I race and practice would trounce

most of us on a clapped out 04' yz250f..........learn to deal with it.

your dear right :thumbsup:

your dear right :thumbsup:

Sorry dead right  :thumbsup:

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Mitch Payton ? Who is he? ............

Plenty of other guys building fast 4 strokes. ( reliably )

I built a kx250f that could pull a stock kx450f so I know a bit about it.

anyways , if you don't have the experience, best to do minimal stuff.

Al

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Besides, it's fun to do stuff like this! Sorry I can't help with a pic Adam. I probably used your pics as a reference point for mine anyway. Please keep us updated on your progress. BTW I got the exhaust polished very smooth from top to bottom. I just had it pulled apart after about 30 hours and even with the carbon, it is still very smooth. Also, your dual FI genius is still paying dividends for us. Thank you!

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