Head Gasket Questions - OEM with Overbore & Coolant Leak

[boosted-lt1]

Hey guys - Couple of questions on head gaskets and to possibly rootcause a leak.

Combo: 2000 CR500 / '89 Motor / '86 style HF-1 head / 1.5mm Over

Running a Cometic 85-88 (thicker) head gasket to get compression down with HF-1 head and pump gas. Started up the bike and I'm leaking out of the front of the head. Actually most of the coolant is bubbling up through the stud/nuts on at least 3 of the forward studs. It was hard to tell if the leak was actually coming from the gasket area or just dripping down from the studs. I did not use gasket sealer and did not check head for flatness (although head was re-installed as-is and didn't leak before)

I re-checked torque and they were good. Gave them about an extra ¼ turn. This improved the seal but still seeing little bubbles coming up the forward couple of studs.

I’ve ordered Honda gasket P/N 12254-ML3-881 which is the 3 layer for ‘85-‘88. However I’m not sure I can use this with a 90.5mm bore – Can anyone confirm? Without removing the gasket from the package it looks like the ID is about 90.2mm.

If I can’t run this OEM gasket due to my bore size, can anyone recommend a good one? With or without sealer?

I have not taken it back apart yet to check, but I suppose if the head measures more than 0.002” out for flatness I’ll need to work it in with some light sand paper on a granite plate?


Thanks,
Scott

[OUTKAST INC.]

I have an extra head that is cut to use o rings and no gasket , stock compression 1995 , works great and runs cooler than stock ...

[boosted-lt1]

Thanks for the info. But I'd rather not introduce a whole lot of machining here or have to buy a new head just yet if you meant you have a head for an offer.

Seems this thing should be sealing and I've either got a bad Cometic gasket or a warped head. I'd still like to know what is the largest bore you can run with an OEM head gasket.

Thanks,
Scott

[lms1977]

I have an extra head that is cut to use o rings and no gasket , stock compression 1995 , works great and runs cooler than stock ...

I like that idea sounds like a better solution than the gasket