Head milling

I need to get my cylinder head milled. How much can be removed without valve interference? Stock head, valves, cams and pistons in a '78 KZ1000 LTD. I think I'd like the compression upped a little for mid range torque improvement.

A couple guys on here will probably know for sure but check out this article on another forum...
forums.dragbike.com/forum_posts.asp?TID=15431

racer54 wrote:

A couple guys on here will probably know for sure but check out this article on another forum...
forums.dragbike.com/forum_posts.asp?TID=15431

Thanks for the link. Nads is asking about a motor with domed 10:1 pistons. Not exactly my situation, but informative. I didn't think there was that much clearance between pistons and valves. Maybe Larry C. will chime in.

Why not check PTV before disassembly, then you will know how much room you have. You do know that this will retard the cams.

is head warped?
how far down the hole is highest piston?if your just trying to raise compression id rather zero deck height by taking it from bottem of cylinder first,or possibly running thinner base gasket.
cylinders are easy to come by,once a head is excessively decked youre stuck with it.

A stock head will generally clean up between .004 - 010" cut off the deck. That's nothing to worry about with the stock cams, valves, pistons.

Put it on the machine and take .002" for the first cut. You'll see immediately where you stand. I have yet to get a virgin deck head in here that's needed more than .010" to get it right. .008" is real common.

You may see there are little triangular spots that coincide with the same shape on the head gasket. Do not try to remove them. They don't hurt anything. It varies from head to head as to how much they show up. Some they do, some they don't. Be there when they deck it so you can stop them from over cutting it to remove those marks

Look at your block. You'll see they match the little cavities in it between the cylinders.

You'll see 2 of them in this pic on one end of the head.

This head belongs to Stonemaster. His didn't have the marks at all. Sometimes all 4 show up.


Regarding that Dragbike post. Jay is right on the money about moving out from center. I've pistons have to be recut for P/V because the head was decked all the way to the valve seats. It caused the valves to tag the outer edge of the relief pockets on 106 centers with little K410 cams in a 1385 motor.

When you start ripping metal away in serious chunks, you have to take the time to check things. The owner of that motor didn't. He followed some advice he got from someone who said it would be fine because he read it in a forum on the Internet

Ok Mods... Where's are damn DROOL Emoticon we asked for?

Damn it Larry, I just have a LUV/HATE relationship when looking at your work.... I think I just got wood...:blush:

Beautimuss....

Head Decking check.... No doubt....

As in my case, No name (MRE) states cylinder not decked more then .010".... Well, installed everything and as I rotated the crank by hand (Thank the the KZ gods) the valves hit the piston domes... WTF... :blink:

Disassemble and take a better look at the measurements...
Larry had it decked ~ .004" on the head, ever so slight and that measured out to specifications all the way around....

On the cylinder... whoa measured anywhere from .010" - .017" as I went around the cylinder.

Double up the cylinder base gasket and all was good...

OMR

APE Jay wrote:

Why not check PTV before disassembly, then you will know how much room you have. You do know that this will retard the cams.

I didn't anticipate milling when disassembling. My head is retarded enough. I don't need any more retardation. I'll take the minimum off and be happy.

Tom.. You accomplishing the milling yourself or 3rd party?

If self, images please during the process would be way cool to see the milling process in action...

OMR

PLUMMEN wrote:

is head warped?
how far down the hole is highest piston?if your just trying to raise compression id rather zero deck height by taking it from bottem of cylinder first,or possibly running thinner base gasket.
cylinders are easy to come by,once a head is excessively decked youre stuck with it.

The warp measures between .003" and .004". I just figured if I have to pay to have the head milled I might get some free torque. It now seems like too much involved to be worth it. I'll have it skimmed minimally.