Head Skim Problem

[Mikey427]

I had my head in the machine shop for a camshaft bearing repair and the guy skimmed my head without even asking. I didnt measure how straight it was before, but since the head was not off due to overheating or a blown gasket, I think it might have been ok.
The main problem though is that I dont have a clue how many times the head was skimmed before and how much he skimmed it. There is no data on the clearances in any of the manuals, the only thing i know from the race manual is that the stock base gasket is 0.2 mm and that the race one is 0.1. So theoreticaly, if the head was down by 0.1 i have nothing to worry about. I have a brand new head which I am saving for latter, so maybe i could measure the height difference, but i think thats problematic as well. I tried with a caliper and it is bloody inexact. Another issue is that the skim was probably done at an angle, because the valves on one cylinder are touched a little bit, but on the other side, they are intact.
I am thinking i might have to get yet another skim and to have both sides even and then get a fatter custom gasket, either head or base. But maybe (and i really hope so) this is not neccesary. Basicaly I am now looking for a reasonable wayt to measure how much the skim took off and if that is within the limits. If the skim is at a slight angle and it wont mess with the compression too much, so be it.
Any ideas how to solve this problem?

[Flatowtornowt]

i would suggest a dry build to find out the squish

[rmkd177]

. Another issue is that the skim was probably done at an angle, because the valves on one cylinder are touched a little bit, but on the other side, they are intact.

Are you saying:-
That the head was skimmed with the valves in the head?
And that the more appears to be taken off one end or front to rear?

Regardless of how much is taken off the head this does not affect the squish. If its any consolation when i tune an engine i have the maximum they can take off...without intruding on the seats...this can vary as Kawasaki's are notorious for not being consistant...it can be as little as 0.3mm up to 0.8mm.

[Mikey427]

Yes, exactly as you say, the squish is not relevant here and yes, the skim was done with the valves in. As for the angle, what i meant was from left (cylinder one) to right (cylinder four). But now that I looked at it again, I realized it is actually only exhaust valve number one in cylinder one that was touched, and the inlet was intact, so either the valves have different clearances which is very probable, or he messed up in both axis. Or maybe that one valve just was not sitting right due to carbon. I dont know. But really, the angle does not worry me that much, I can live with that. My main problem is if the tolerance is within limits. Here is a photo of the scraped valve, the shiny spot is it. I have the spring retainer slid on, dont let that confuse you.

[rmkd177]

My main problem is if the tolerance is within limits

What tolerance and what limits are we talking of here ?????
You seem to be particular about this and yet leave your valves in when work has been done on the head and also left in for the skim. The valve's need to come out to check them and at the very least lap them in before reassembly.

[Mikey427]

Sorry, I probably dont make myself very clear.
I had the head in a machine shop to get the cam caps skimed and to get the cam bearings rebored, because they were gone. This job does not need the valves to be out plus i was not sure if the guy would be able to do the job. He said he wants to see it first. Thats why i didnt go through the hassle of removing the valves, thinking in the worst case i will just take them out afterwards to clean the shavings properly. When the guy saw the head, he said he will do it and told me to leave the head there. So i did. I never asked him to do a skim on the big surface that meets the headgasket, and as i said i doubt the head even needed it, but he simply did it anyway without even asking. He said they skim every head they have, that it is their policy or something like that. They probably dont want people coming back saying the shop gave them a warped head. If I knew he was going to skim it, of course i would take the valves out. In fact they are out now, i will lap them, i checked the wobble and i got new oil seals to put in.
The tolerance i am worried about is the valve to piston clearance. I dont know how many times the head was skimmed before and how much the guy took off. As far as i know, the head has no skim limit marks, so i wonder how the guy knew if the head is still usable after the skim. It didnt seem like he really gave a toad either. It looks like he simply did a quick skim and that was the end of it for him. WHether the skim was still ok apparently didnt concern him much. The possible wrong angle is another thing, but thats a secondary detail for me. I just dont want the valves meeting the piston.
You seem to have some experiece with this. Judging by the valve scratch, do you think the head is past the limit?

[rmkd177]

I would say it will be ok. There appears to be plenty of carbon on the valves suggesting it had more than enough clearance
prior to the skim. What is generally overlooked is the affect a worn camchain can have on valve timing and valve to piston clearance. When the camchain wears the adjuster takes the slack up from the rear and so pulls the cams backwards..retarding the valve timing...which brings the exhaust valve closer to the piston at the 'check point' (12 degrees BTDC) but takes the inlet valve further away at the 'check point'. This is why a race engine on tight clearances has a tendency,if not checked regularly to 'drop' valves...'drop' usually refers to the valve coming in contact with the piston and the subsequent damage, the exhaust valve is more often than not the culprit.

[cargo]

And the moral is overhaul your top end regularly

[Mikey427]

Thanks, i feel a bit better now

And dont worry, a new cam chain and chain guides were the first things i ordered.