yup, mirror finish on the exhaust or best as you can, this aids on the carbon built up to min. getting the port floors and roofs equal is the key, the air has to move down the tube at equal speed. I did an idea i read on the golf head. At the point to the inlet valve, changed one side past it sligtly bigger. Not much tho. The idea was to spin the air past the valve stem. Air pressure one side was greater than the other, making the air going in twist past the valve head. This swirl idea was to aid in the "laying" on top of the piston. better spead of the fuel and air mix.
The CFM increased of course, and the proof was on the dyno in the end. Plus the better fuel econ.
The valves seats. i asked a friend who owns a machine shop, to lathe the cast down by 0.5mm and knocked the seats back in. This makes the valves seat more flush in the chamber. Badly done in the chineese factorys by the look of it.
as too 200cc yup i do see then around. i rekon the bike breakers have a few floating around on the shelves.
I use a dremmel and all different grades of paper. flap wheels and drums.. Mind you loads more fiddly on a bike. The ports are a lot smaller.
Stones to start with shaping.
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Originally Posted by Weldangrind
Like you, I've done quite a bit of reading about porting and polishing, but I've only done mild work so far. I'm interested in trying a kit I saw that had all of the necessary bits from Standard Abrasives: http://www.summitracing.com/parts/SAI-260001/?rtype=10
From what I've read, it's ok to make the exhaust bowl and port mirror-smooth, but the intake needs some texture for proper atomization. I've also read that one has to be careful about how much material is removed on the intake side; the goal is to smooth out the short-side radius and blend the bowl (and pushrod area if equipped). It would sure be nice if we could quantify the results on these bikes, so we know if we're helping or not.
How are you sinking the valve into the head?
On the 200cc engine possibility, do you have much of a supply of 200cc OHC Hondas in the UK? I've read that they're kind of scarce. |