Topic: 750 top end oil leak

[flybox1]

I dont know about the latter K's, but on the F2/3, there are 4 studs which pass through the head but are also in the vacant fin spaces between 1&2 and 3&4 in the head.  these studs are exposed to the elements, and can rust.  if they dont have the crush washers on when torqued down, the heat cycles can allow for a gap under their torque nut, and weep oil....
The main issue is, you cant reuse old 'crushed' crush washers.  New ones, or anneal the old ones....
Thousandson said he re-used the old ones.  I suspect this is (or will be) the leak spot.

F2/3 Head Diagram  #14 below.  Part #90441422000
Notice its UNDER an Acorn nut #15
The acorn nut itself adds another layer of protection from oil getting down the threads, or rust/moisture creeping up.

[madmtnmotors]

Are you guys referring to #14 in this diagram?: http://www.hondachopper.com/engine/fiche_pages/K7/K7-Head.pdf

Never realized these were potential problems.

No. The diagram you are referencing is for a K7/K8 and part #14 in the diagram you reference is a plain washer used at all head nut locations. The 77' and 78' "F" models are different in that four of the head nuts are acorn nuts, and these four acorn nuts use copper washers in lieu of the standard plain washers to prevent oil weeping out of the locations where the four oil returns were abandoned in the 77/78 "F" models only. The 77/78 "F" has a unique head casting that exposes the shafts of four of the studs to the atmosphere so they could no longer be used as oil returns. The barrels are also unique and require a fat little o-ring at these four locations at the base of the cylinders to keep the elements out of the crankcase and to keep oil from getting pushed up from below.

flybox1 has the correct diagram.

[AintNoEasyWay]

Ah ok, thanks for clearing that up!

[flybox1]

The 77' and 78' "F" models are different in that four of the head nuts are acorn nuts, and these four acorn nuts use copper washers in lieu of the standard plain washers to prevent oil weeping out of the locations where the four oil returns were abandoned in the 77/78 "F" models only. The 77/78 "F" has a unique head casting that exposes the shafts of four of the studs to the atmosphere so they could no longer be used as oil returns.

Yes!  Just like cam tower pucks, these 4 copper crush washers keep the outside out and the inside in