gs 850 head pitted?

[Guest]

Is this normal?

[Toasty]

Did you use a wire wheel on the mating surfaces...?

[Dogma]

Don't sweat it. Look on the head gasket to see where the real sealing happens. It's just a few mm around the bores, the area around the rear corner studs where the oil passages are, and a few mm around the cam chain tunnel. The rest just needs to be complete enough to keep the head level. There's no need to have a nicely machined finish all the way across the head. Where it really matters, the old gasket probably protected the head. The pits I think are corrosion due to moisture that got into the gasket, but not past the sealing faces.

I can't see enough detail in your picture to be sure, but I think it's probably OK.

[chef1366]

That's fine
How are the valves and seats?

[gsrick]

Message from the Ghost.....

... to get that head re-surfaced at a machine shop. Should be under $20.00


Eric

[Toasty]

Is that really okay to use as-is? I see a few deep dings on the fire rings, and the head gasket would hold even with the pits and scuffs?? I've always heard that even a hair sized scratch will compromise the seal...

[rapidray]

I would have that head surfaced if it were mine or I were building it for a customer. Do a minimum cut on it, just enough to clean it up. .010-.020 should be plenty. Ray.

[chef1366]

I would listen to Ray.

[kdo58]

This is a spare motor I had picked up. Five exhaust bolts broke off on my other motorn and it has 70, 000 miles on it. So the top end needs to be rebuilt on one or the other.

[bwringer]

I would have that head surfaced if it were mine or I were building it for a customer. Do a minimum cut on it, just enough to clean it up. .010-.020 should be plenty. Ray.

Yup.

They all have that pitting in the middle parts -- as noted above, this area is not crucial to sealing, and moisture seems to seep in over the years and cause the pitting.

A light resurfacing would make it nice and even in the important areas, but some of the pitting will still be visible.

I'm fairly certain you'll need to remove the valves for the resurfacing. Last time I had this done it was $45. YMMV, of course. Make sure you ask how the shop plans to do the job -- "throw it on the big belt sander" is not an acceptable answer, although it's one I've heard...

Next time you work on a cylinder head (and there shouldn't really be a next time with this bike), look into Roloc or surface conditioning disks instead of a wire brush. They're a lot less aggressive.

[rustybronco]

A 'flat' table saw, a flat piece of glass and some sand paper glued to the glass with contact adhesive should work as well. It would be better if you had a straight edge of some sort to check the heads surface for flatness as you go along.

[Nessism]

It cost me $100 to have both my cylinder and head surfaced. Used two different shops, on two different engines, and both charged the same. Both guys were very hesitant to cut very much even though I told him there was no problem with doing so. The pitting was pretty deep on both engines but the guys said there is no need to worry about the non-critical areas of the head. Couldn't argue with their logic.

[kdo58]

Well that is the least of my problems now that I took the cyl. Off , mine has no cross hatches left in the cyl. Bore a d one cyl. Bore has a small score mark. Not sure what I am going to do.

[chef1366]

Well that is the least of my problems now that I took the cyl. Off , mine has no cross hatches left in the cyl. Bore a d one cyl. Bore has a small score mark. Not sure what I am going to do.

Do you catch a nail on the score?

[kdo58]

I went out and checked , no my nail does not catch on it,