Cylinder head-resurface?

I took apart the 900 last night, trying to figure out this major smoking thing. I'm literally going thru everything, found a valve guide that needs replacing..
But..
Can anybody comment on this pic of the head surface? It's right next to #4, which is the one that is burning oil. It looks a bit like a casting issue, sort of pitted a little. Still, they look to be in the .001-.002 deep range..
Should I just resurface it and be done with it? or is this normal?
Thanks!
K

I'd have it milled and don't forget to replace the valve guide seals while you are at it.

Zippy

any idea how much you can take off safely?
I've got new seals in place, but don't want to go much further if this is too screwed up...
thanks.

Thats the cyl block .
Forget that ,,,,,,,,,,,,
IT DOES NOT SEAL THERE

Just air moves through there .

The seal is at the liner and that copper crush washer around the stud hole .

If you had a bad seal at either place it would NOT make it smoke .

Don't go milling on the cyl.


(Sorry ,I messed up ,the copper crush washer is part of the gasket.)

Post edited by: MDawnz1, at: 2007/09/12 16:46

MDawnz1 wrote:

Thats the cyl block .
Forget that ,,,,,,,,,,,,
IT DOES NOT SEAL THERE

if you looked closely you would see that it is infact the head and that the hole is a valve seat.

i took 30 thou off my 750 head and it just stated touching the outside of the valve seats. with yours the marks look like they are just from the old head gasket a light skim at the machine shop to clean it up should do the trick, and shouldnt upset the cam timing to much.
the exhaust studs will have to come out, machine shop can do that for you though.

It's not uncommon to find that some surfaces of the head can develope this kinda look. There are some "pockets" in the cylinder block that sometimes leave a "similar impression" in the corresponding head surface. You my not know if you have any overall warpage yet? .020" should be "safe" though, as long as it hasn't been cut before? Get it "flat" again and see how much it takes?

no warpage other than about .002 between 3 and 4, the rest if really straight, i checked it on a straightedge that I checked on a milling machine bed, so i am pretty confident it looks good.

I would leave it alone if it's straight. The previuos poster is correct. The oil only flows in a few areas in the head. Center o-ring, or gasket area on earlier versions, and stud(s). You should really check cylinder leak down hot, to determine condition. Valve guides, and stems, are a good oil burning source, but ring alignment and cylinder taper seem to be common. If you have it apart already, have you measured your ring endgap? Those head gaskets are pretty thick and cushy. I like to put a little Yamabond in the center o-ring channel, and immediate surrounding are.and a swipe on the head center area as well. A good tourque sequence with a good tourque wrench. Anyway, it seems to work for me. 2 cents worth, if that.

yep, yep and....yep. I did a leakdown test on all 4, cold though. #4 was 15% or so thru the crankcase, the others in the 7-10% range, thru the crankcase..think I did not do a good job with the honing/rings.
got it all apart and have gone thru the head completely. Valves all the right size and tru, has new viton seals from before, did find two guides that are questionable though. Checked end gap on new rings the first time, but not piston/cylinder wall clearance. This time I checked everything, taper/out-round all good but one cylinder 3thou over and another 2thou over max.
I use the single head gasket with permatex in the middle where the o-ring was, gona try yamabond.
It's weird that so much oil is getting into #4, and yet that one has good clearances, new seals and the guides are super-nice.
What do you mean by the head-center area, is this the area around the center o-ring/cam chain well?
I think now the best thing is to just get another 900 cylinder (thanks Brian kz10006), and get it bored to either new pistons or the set I have, new rings, and take better care installing them. It's good to be able to check off for sure a bunch of stuff as good, so at this point it's got to be the block/pistons.

Simple question ,,,,,,,,

Don't get mad ,,,,,,,

Are all the rings on that cly. installed with the marks UP ?

Like I said , just a question .

WHAT THE!!
yeah, marks on the second ring set up, but there are no marks on the first ring set. chamfered a slight bit on both sides as best i can tell...
thought maybe i had the scraper ring overlapped, like on jeffs z1 ent website, but no, they wer in good.
I did get the rings from jeff, maybe i should have called and checked with them, but even with a 10x lupe i could not see any 'n' marks on the top ring...