So I got a '85 LT250R, gonna shave the head, how much is normally taken off? I don't need to run AVGAS but if I have to I will.. meaning that if I take a little too much off it isn't a big dealio to me. I raised the exhaust port a little bit while I was porting it out so I have to do something to gain some compression back.

 

Without remachining the squish area about the max you can take is .015. If you can cut the squish band the correct angle and width, then take .020 to .030 to stay with pump gas.

 

should I just copy the old angle of the squish area?

can it be changed to improve performance?

 

For good wide power, I would stick with the deminsions of the old squish. A smaller narrower squish will increase top end, but the Zuki head has a good design to begin with. A lot of R&D goes into aftermarket head designs, but the factory stuff is usually real good. Bolt it on and use a piece of solder to measure squish clearance. It shoud be around .035 minimum. Any more than that and you can take it off considering it doesnt get you into trouble on the head part as forementioned. The compressed gasket usually goes almost 1mm by itself.

 

interesting. so basically increasing the chamber that has the spark kernal will increase the top end? well, technically it would be smaller though because the head would have to be cut to get to that point anyway... but still... I understand the concept.

It looks like the squish area starts at about .025-.035" so I will just cut to that spot, and see what kinda PSI I end up with. then go from there. I'll clay it too to see how much clearance there is.