Cylinder head o-ring question
 

Ok,, so I'm finally getting around to messing with the blown o-ring gaskets on my 97 gg 250. Tonight I rolled the bike into the center of the garage and started in,, 25 minutes down and I have the cylinder head in my hand. Yes the inner o-ring was crunchy and traces of blowby in two passages. I guess that's the smoking gun. I go thru the sleeves of gasket kits from engine kits I have done or helped others do. I also got a couple given to me from guys leaving the gg fold back in the early days. Out of everything I have a set of newer 250 o-rings and I think a set for this. The outer o-ring is not black but a brownish. Is this a cyl head o-ring? Or for something else? Size is perfect.

Steve,

Brown is good, likely EPDM, better than BunaN rubber. I've had inner head orings like this but never an outer.

Ok,, great I feel better about putting this back together. Thinking about taking the head up to Mike up in Dupont to have it surfaced. since I did have an issue.

Check the cyl too, especially the o-ring grooves. Easy to clean up the surface on a glass plate with some #400. Probably even do it on the bike with a small plate and stuffing the bore and water jackets.

Usually when that rubber is hardened and takes a set, its a sign of high temps. Could the bike have overheated for another reason and caused this?

I swapped out carbs and stayed with the jetting from the old carb. May need to rethink that,, it's the same sized carb but a newer one. Also an airstryker. I did not think of rejecting for that factor at the time. Sounded good and ran 100% so I figured carb was good.