Big bore head gasket

cknight · Post by **cknight** » Sat Oct 21, 2017 1:53 pm

The Bore-Tech 66mm gaskets are a good quality piece (made by Cometic). I've used those for many years with 358cc and S12 applications, with no issues. Regards, Chase

GregMcN · Post by **GregMcN** » Sat Oct 21, 2017 3:08 pm

Unfortunately the bore tech ones were too big for my bike hence going for the copper.

Greg

cknight · Post by **cknight** » Sat Oct 21, 2017 3:56 pm

If you have the solid copper gasket, and the top of the sleeve is flush with the top of the cylinder block, a copper spray sealant should be OK. If the sleeves are slightly above the block, a light coating of something like Permatex Form-A-Gasket will help seal around the oil passages, as the solid copper will not compress like a composite gasket. Is this for street or race usage? Regards, Chase

CharlesM · Post by **CharlesM** » Sat Oct 21, 2017 5:27 pm

My head and barrel are totally flat and oil does weep from the gasket. On that basis I will use sealant for the next engine rebuild. The bike is working hard though, revving to about 10,000 with high compression and high lift cams so I can forgive a bit of weeping.

If it's not too late, i recommend getting two. Then if you have to pop the top off you don't have to mess about annealing the gasket when you just want to fix the issue and put the engine back together again.

GregMcN · Post by **GregMcN** » Sun Oct 22, 2017 2:01 pm

Thanks Charles, CK

Bike is just for the road and liner is flush so will get some spray sealant.

Ordering 2 gaskets would have been a good idea but as I was not 100% sure I was ordering the right thing I just went for the one........... hopefully will work OK.

Greg

malcolmgb · Post by **malcolmgb** » Tue Oct 31, 2017 5:13 pm

Cometic will make a custom gasket to your specification, I won a voucher for a gasket of my choice once, rather naively I didn't realise who I was dealing with until I visited the factory and after talking with one of the Directors didn't continue with the prize, looking back I wish I had asked for a 'T' shirt or other momento.