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Base and head gaskets - sealant or dry?
- Thread starter timtune
- Start date
New like mid 70's honda.
Uhmmmmm
Pretty sure he is referring to the gasket.
Clean and dry is key... and clean.
Lap the surfaces
Check head studs for stretch (I usually replace them)
If you are going to eliminate the base gasket , be SURE to measure piston to valve clearance.
If you eliminate the base gasket, apply 3Bond or the like
If you use the base gasket: smear it with grease and it will come off in one piece
NOW: What type of head gasket are you using?
If you're using a metal gasket, apply a thing layer of paint to the gasket, let it dry
If you're planning on ever taking the head off again, use a copper gasket. They're cheaper.
If you're using a copper gasket, be sure to anneal it before use. YES YOU ANNEAL A NEW COPPER GASKET.
All other head gaskets go on clean and dry. No goo or sealers, just CLEAN.
Torque the head GRADUALLY and re-torque after a couple of heat cycles, then again after 10 heat cycles.
TK4
Well-known member
That might work on a small block V8, but there ain't no way on a SOHC Honda CB750. It would involve removal of the motor from the frame.
Mad Mike
Well-known member
I use Permatex copper gasket spray on both sides. Never had a gasket fail.
It's not absolutely required, a friend that builds race engines introduced it to me, I use it on everything now.
Just use it, you'll be fine.
Relax
Well-known member
Copper spray on the head gaskets is one of the few things my engine builder does to bulletproof SXV motors, even though not specifically called for in the factory service manual (the one-liner that just says "Fit a new cylinder-head gasket").
Roadghost
Well-known member
You should be following the instructions in your service manual. The base and head gaskets on most bikes (but not all) go on dry. Strongly recommend you use reusable gaskets like Fel-Pro.
Mad Mike
Well-known member
The guy that introduced this to me builds stupidly powerful race engines for street cars. I think using copper is more common with race builders than back yard guys because it delivers clear benefits to them -- benefits that are not usually required for a regular overhaul.
If you're reusing a new steel/viton gasket -- I'd say it's not required - reusing one and spray copper is a must. A 20 0 year old NOS paper/copper gasket -- I'd say yes.
Copper spray is effective at sealing up small irregularities that could leak, it's also 50% more conductive that aluminum so even a fine sprayed on layer conducts heat away from hotspots - helpful in an air cooled head.
A $10 can will do a hundred motorcycle heads -- so why not?
Mad Mike
Well-known member
You can reuse most metal head gaskets. Steel gaskets will have lost some of their viton coating (the black plastic film printed on the gasket) so they benefit a lot from copper spray when re-used. No annealing for steel.
Copper it MUST be re-annealed to soften the metal -- if not it's too hard to form a good seal and you risk leaks. If you can't re-anneal a copper gasket, copper spray will work in it's place -- coat both sides.
There same people probably think a car tire is just fine on a mc.
It's cheaper?
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