Base and head gaskets - sealant or dry?

[Roadghost]

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.

Yes, agree. On an air cooled engine you can get the seal just as well with if you reuse a steel gasket on the same parts. I've done it on my Honda. Obviously the best option is a new gasket, and you don't want to reuse a gasket that is like, 10 years old. This doesn't apply to a water-cooled head though because the seal is different and a lot more critical. Not a fan of copper myself though some guys use them with good results, others warn against it. I never saw the point in copper when steel is perfectly fine and less expensive. Some say that copper has to be retorqued periodically because the vibrations make it crush and it begins to seep, but I have never seen proof of that.

When I was rebuilding one Honda engine I bought about three different steel gaskets. One of the three measured slightly thinner with Vernier calipers. I gambled with it just to get the higher compression, though I never thought it was significant. I think it was a cheaper Chinese gasket, but it worked fine.

 

[Brian P]

unless the gasket you should replace is no longer available , or you are forced into a teardown in the middle of nowhere , why would any normal person reuse a gasket ?

Those are exactly the reasons to re-use a head gasket ...

I've used the copper-spray stuff a couple of times on re-used head gaskets, haven't had an issue with it. Once because a new gasket of the thickness that I wanted and already had was no longer available, and once because I wanted something to get done and couldn't be bothered waiting for parts.

 

[Mad Mike]

unless the gasket you should replace is no longer available , or you are forced into a teardown in the middle of nowhere , why would any normal person reuse a gasket ?

On old bikes this was common practice. In the days an SOHC Honda like OPs was made, there were lots of bikes that had decarbonizing as routine maintenance.

You didn't replace head gaskets unless they failed or were damaged. Just like you dont on your lawnmower.

Late model water cooled engines have more complicated gasketing and tolerances, they take a lot more time to change if they fail and failures can be catastrophic -- this nakes it practical to renew every time. No so for the old stuff.