Planing head or not

After reading
members.tripod.com/gpz_rider/technical/FAQ2000.htm

And after I bought a K810 kit, I was thinking about planing the head on the old zephyr 750.

What do you think?

What comp is the piston kit.
If it's 10.25 - 1 you don't want to go higher with pump gas.

The exhaust seats are right near the sealing surface. Milling the head more than just a nominal amount will hit them which is not an ideal situation (particularly if you are the guy doing the cutting.)

Why plane it, is it warped?

If anything street port job and cams would really bring it to life!

I think you are right, I'm not going to mill it.

You are kind of putting the cart in front of the horse aren't you? I would wait until you take the head off and then check it for straightness first. If it's within spec then leave it alone and move on. If it isn't within spec then have it surfaced. Don't fix something if it ain't broke.
Rick H.

The seats are cast in and are quite large but I doubt hitting them would be a problem if it were milled to take out minor warpage. .004" is the limit before it has to be milled. I've seen worse. On the "junk head" I just installed I cleaned up the casting slag and lines, ground out the seat ridges where the ports enter the seats and adapted the intakes to the larger intake manifolds for my 33's. Just that light porting made a lot of difference. The bike always had a surge of power "coming on the cam" as it got to the 7-8000 RPM range even with stock cams but now when I get to 7000 it wants to bury the redline. It's like I gained a couple more cylinders and someone kicked me in the ass. :woohoo:
When I first got the bike in 75 after 1000 miles I grabbed a handful and it felt like the devil grabbed me by my jacked and yanked be forward. :ohmy: I got use to the power but now it's like I got a new more powerful bike. :evil: The Andrews 1X cams I have are great but now it's time for larger ones and a 1075 kit.
Using the power is good for the soul.
Steve

Depends on your final engine setup, and what cams you use. but probably not necessary unless you are below 10.25/1. decking the head will also change the valve pocket location on the pistons.

What is more important is the squish. One of the benefits of a large overbore is that the ring around the dome of the pistons can be used to create a "squish band". If the squish (piston to cylinder head) clearance is large (over .045") then using a thinner head gasket, thinner base gasket, or decking the cylinder block to reduce the squish can be beneficial. This will lead to an increase in static compression, and cranking compression all things remaining equal. this will also change the valve position relative to the piston dome. measuring and claying your pistons becomes very important

If you get longer duration cams or re-time your cams for a later intake closing point you can effect the cranking compression. 12/1 static comp can have the same cranking compression as an 8/1 depending on the cams. It depends on more than the pistons alone.