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<div class='quotetop'>QUOTE (94ZR580 @ Jan 2 2007, 02:06 PM) <{POST_SNAPBACK}></div>
If you haven't ridden it yet I would not be cutting heads to address an assumed, unknown problem. Did you you look into the base gaskets? Maybe someone used fibre base gaskets and the cylinders are sitting too high. Exhaust ports should not effect compression numbers because you don't have any compression until the exhaust port is closed. Cutting the heads may have decreased the squish height, but did it adversly affect the squish shape? The shape of the squish band is important to proper combustion and, therefore, power and engine health. I hope you didn't make changes that will require more octane than premium pump gas to keep detonation at bay. I'd say don't cut any more until you know if you have any problems. Ride it and you'll find out if you caused a problem with indescriminent head cutting, or if it had issues when you bought it.[/b]
The exhaust port height does effect compression, the higher the port the lower the compression at cranking. What you do not know is what is the dynamic (running) compression the pipe design along with the max RPM of the engine will effect your dynamic compression. An engine with a high exhaust port and short pipes will have low cranking compression but it may have high dynamic compression and it may make a lot of power at high RPM. I would not modify your heads until you have determined how the engine runs. It may not need or want any more compression for trail fuel.
 
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