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So right away, these images alone give a great idea as to why we only get a massive 14hp from a 230cc engine.
The intake side of things really isn't too bad, but there are a few things I observed right away with just my eyes. The intake port is smaller than 30mm. Without going and digging out my calipers to measure, I would estimate it to be around 27-28mm. The casting around the valve guide is rather obtrusive into the port, but surprisingly, there is very little in the way of flow restriction from the short side radius. There is a little bit there, but way less than many other heads I have worked with. On the right side of the port is also a slight intrusion into the port that causes a small narrowing of the ports cross section about halfway down the port. It's nothing big, but another flow restriction.
The exhaust side of things is by far the worst. The pictures really don't do it justice. There has to be at least a 30% reduction in cross sectional area at the valve guides greatest protrusion into the port as compared to the exhaust valve area and port size. The exhaust is literally leaving the valve to slam into a huge bottleneck halfway out of the head.
I would honestly not be surprised that proper porting to simply even out and open up the restrictions in the ports, as well as a port match with a tapered reduction through the port could easily pick up a 20-25% increase in power without altering the lovely powerband this engine possesses. I may not even bother decking the head at all.
Oddly, I have never been more excited to do head porting in my life. Now I just need to find the time lol.
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