KDXRIDER.NET

On my recently acquired '98 KX125, I found that the cylinder head has perforations of sorts. From what I can tell about the bike, ( see here: http://www.thumperta...__fromsearch__1 ) it is an ex-pro bike, possibly with a Pro Circuit Engine. I've seen heads like this before, but I can't for the life of me remember where, and now that I own one, I'd like to figure it out. Has anyone got any information on this head design? Advantages or disadvantages? Looks neat that's for sure!

Hard to think the holes would help anything.

Could be some backyard idiot hack with a drill thought it would be a good idea, but I'm curious to know what would be achieved by doing this?

I saw that pic when you posted it over at TT. It puzzled me then and it puzzles me now. The only idea that my crazy brain can think of the idea behind it goes like this...

Charge velocity gets faster and denser at the outer edges of the cylinder than in the center as the piston pushes upward. The little ports in the head help direct the denser mixture to the spark plug to help insure a good mixture around it. Once fired, these same ports would allow the burning mixture to reach the outer edges of the cylinder quicker helping to promote a faster and more equal burn.

Eh, just a crazy idea! Please post up if you ever find out what they are really for! BTW, you thought PC might have something to do with the engine. Did you contact them about it?

Since the holes start in the squish band, I would suspect SS is correct. I'd send a pic to Ron and get his 2 cents.

i'd run it then compare with a "normal one".

I have seen this before. Maybe not as crude, but I thought even some of the "Phat-heads" heads had these.

My take is the holes are there to increase combustion chamber turbulence. That's the whole idea of the squish band. As the piston comes up and squishes the gases out from the squish band area, they flow to the central combustion chamber in a turbulent manner. The gas flowing through these "nozzles" would add to that turbulence. Maybe yes…maybe no???

With the holes in there it is lowering the compression.