Porting

[Coop88]

What is porting? Is in the manifold between the Carby and the engine or is it the actual inlet and exhaust part inside the head? Do I just polish down all the rough imperfections or do I actually grind away and change the metal aswell?

I've got a pitster pro 155z engine that is stock as it came. I'm using a 26mm oko flatslide. How much metal can I ground away? Are we only talking 1mm? Or bigger?

Any tips be good thanks or just a link to a decent YouTube vid of it. I was just hunting around but didn't have much luck. I've looked at other threads on here but they aren't basic enough for a nooby

 

[zwebx]

Where can I take my bike to get ported and polished? What exactly does it involve? Does anyone know of any places in west aus?

taking the head off the engine, removing rocker gear and cam and removing the valves (i did anyway) and then using a die grinder take out material while considering the flow of air and how it behaves or you do somthing like swirl it, making the air swirrl around the port for faster airflow im not sure about a shop.... if you were in melb i would do it...

 

[Coop88]

Thanks man I wanna have a go but I might try on my ****ty eBay bike before I do it on my new one lol. How do you know how much to take away? Is it different for different size engines? Thanks man

 

[motorman]

Is it when motorman has a few too many Ports while camping to warm up and get's a bit lose?

Yeah I'm positive that's it!! haha

 

[my67xr]

here is an old lifan 125 head i had,
i gave the ports a clean up with a dremel type die grinder, using a carbide burr, and the stone burrs, and finished it of with some sand paper rolls.
i basically opened up the ports,
matched the intake side to the gasket size, and took some metal away from the valve guide area, and the short returns (inside edge of the port where it turns down towards the valve heads), this was done on both the inlet and exhaust posts
i also took a bit of metal out from just below the valve seats, to straighten the flow, and removing any restrictions.


exhaust side before,

exhaust side half way through porting, it was smoothed out with some 180 grit paper after this stage

inlet side before,

inlet side after porting,

combustion chamber before,

combustion chamber after,

you can compare the before/after shots, seeing the raised hump around the vale stems and then see it cut down and smoothed out etc
the combustion chambers shots show the areas around the valve that have been smoothed out.
and you can see inside the intake/exhaust ports where it is a heap smoother now.
this took around 1.5 hours to do, and made the engine run a fair bit better.
it gave me more low down torque, and also gave it a bit more top end.

cheers, craig

 

[my67xr]

the exhaust port pics above are from 2x different heads, i forgot to get a before shot.
and i didnt get a before pic of the combustion chamber with the valves removed.

when porting the head, you need to be carefull not to grind the valve seats, where the valves seal to the valve seat in the head when closed.
the intake port should be left slightly rougher with the sandpaper swirl marks on it, to aid the mix of fuel and air.
the exhaust port can be polished up like a mirror if you want to go that far but doesn't really gain much more from it.

 

[macca97]

when i ported my head i didnt polish the intake and made the air turn which helped the fuel atimize, but i polished the exhaust port.

 

[DHZ_XR8cing]

Porting the head dont always opening up the whole port. It is more the process off taking out metal that gets in the way of the air flow and making it less restrictive.

 

[Coop88]

Awesome man thanks heaps for the detailed pics I finally understand what everyone is on about! I'm not worried if it makes too much of a diff or not just wanted to give it a go. Cheers