The Inside Line Podcast: Tech Edition | Cylinder Head Modification 2

Porting and polishing a motocross bike's cylinder head is a sure-fire way to get more power... Or is it?

The Inside Line Podcast: Tech Edition | Cylinder Head Modification


When talking about engine mods for motocross bikes, the phrase "ported and polished" gets thrown around a lot. But do we all know what that really means? Turns out, according to Andrew Flores, Engine Research and Development at Race Tech, polishing is the last thing you want to do to intake and exhaust ports. We get into all the different ways a cylinder head can be manipulated and what each modification does so that you can have a better idea of what head mods are available and if any are right for you're motocross machine. 

The bottom of a cylinder head.

Removing material creates more space for more air/fuel mixture, but it also slows down the flow speed.

Looking down a modified intake tract. A rough texture is actually better for fuel atomization - polishing has a negative effect on fuel suspension.

Exhaust port.

Where cylinder heads get bolted up for flow testing.

Different radiused inlets.

The complete flow bench machine with different inlets and fixtures, as well as velocity probes.

Each intake tract is molded to better understand and see the negative space.

Andrew Flores, Engine Research and Development.

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