Milled Head ?
 

How much can be milled before it's junk? And if you can mill the head a little do they make a head gasket that is a little thicker than a stock head gasket?

ROD

Not a lot iirc .008" and that's already pushing it as far as the tensioner and chain guide. You could use a slightly thicker head gasket, but you dont want to go too thick or you'll alter the quench area in the combustion chamber.

Yes, it's 0.2mm max but there are some extra rules (so it's not always 0.2mm max)
The head height plays a role too, new is between 104.95mm and 105.05mm, the 0.2mm max is based on the 105.00 head height.
IOW: never machine it thinner than 104.80mm.
I'm using my MY00 head on the MY05 engine, machined to this limit and without issues, for 110000km. and counting.
:hello:

0.2mm max is based on the 105.00

So the OEM head gasket is 0.76 mm or 0.03"
Spoon head gasket is 0.46mm or 0.018

So if you have a head with 105.00mm and you use a spoon head gasket will it throw of the chain geometry?

The max you can resurface is 0.2mm, the diference between the oem and spoon headgasket is 0.3mm

Is that correct ?

The whole "max you can shave a head" is based solely on retaining proper cam degree, compression ratio/squish area. The head can be shaved MUCH more than the allowed oem spec, many do this to adjust compression, squish, or just maintenance clean up pass. We use adjustable cam gears to correct cam timing though

yes but what about the chain getting loose ?

That you can't correct with cam gears

That's what the cam chain tensioner is for. If you mill the head enough to cause a loose chain, you'll have MUCH bigger problems than that...like the pistons slamming into the head. lol

acording to billman250 if you mill the head to much it will cause rapid wear on chain , chain sprocket and guide , and that clicking noise all the way.

The geometry will be screwed.

now pistons hitting the head is another league of problem hehe

yeah, I've seen the post. I guess I'll agree to disagree. Not saying accelerated guide wear can't happen, but it would take other underlying issues and a lot more than a few thousands of an inch to make a difference. There is a port on the head that floods the timing chain with oil.

A human hair is ~.003" So two hairs worth of difference to cause major issues? yeah, no.

Well let's see what billman have to say about this.
Or another person with experience in the topic.