Why copper washers on motorcycle head?

Question

The head on my motorcycle is secured by 10 nuts, 4 of the nuts use copper washers, 6 use steel washers. Why is it necessary to have copper washers? The copper washers are used on the outer most bolts.

Answer 1

Copper compression washers are common where the nuts are known to back off do to vibration.

Answer 2

For future reference, always give year, make, engine size and model # when asking questions. We need all of that info to give an informed answer.

Copper washers are used as sealing washers, to prevent oil from coming out of the bolt holes.

A previous owner may have installed copper washers, as a short-cut to repairing a problem.

Look for your bike here -

http://www.bikebandit.com/parts/

Check if the washers on the head are different numbers or the same.

Different numbers would mean copper washers are probably used.

Edit -

The copper washers are used as sealing washers.

According to bikebandit - the outer stud holes of the cylinder, are used as oil galleys.

Oil from the crankcase, is pumped up through the stud holes and then diverted to lubricate the camshafts.

There are metal "seals" built into the head gasket, to prevent the head gasket from leaking oil.

Answer 3

guardrailjim has it right, the copper washers are used on the studs that also serve as oil galleys.  On those studs, the hole in the block is larger than the stud and oil is pressured up through the hole to the camshafts.

Answer 4

Sounds like your previous owner just grabbed any 4 washer from the parts bin.

Good luck...

Answer 5

Although others have identified that they are compression washers and are probably holding back a fluid, compression washers cannot be reused they should always be junked (recycled) and replaced.

Answer 6

could be to avoid back-out, the only other use i've seen for copper is to seal a fluid...maybe to battle oil leaks?