I did replace the pucks with new Honda ones and the head was torqued to 10 ft/lbs then up to 15 ft/lbs.
I just did the top end on a 78 750F AND my 78 750K with aftermarket gaskets, no sealer, and no leaks after 1000 miles on each. Peak torque @15ft-lbs
Did you re-torque? After the initial head torque I will let the engine sit for 24 hours, loosen all the head nuts, then re-torque. This is an effort to avoid taking the engine back out after 500 miles just to re-torque... AIN'T gonna happen!
Are the four barrel holes on each side returns and the o ring holes supplies?
Yes.
I do have another new gasket I bought for my bike (78CB750F) that didn't end up fitting...but that's another story all together.
I'm pretty sure the late model F and K head gaskets are the same. I'm also pretty sure the head gasket is asymmetrical and will not fit if it is flipped 180.
The 78 750F was an exercise in engine removal for me due to an oil leak that should have never been. I ended up pulling that engine THREE TIMES chasing a PROFUSE oil leak that left my shin covered in oil on each subsequent "shakedown" run. I started simply, just replacing the "pucks" the first time. Second time I went all the way to the base of the cylinders, where I found that the four abandoned oil returns (specific to the 77/78 750F) were missing the additional fat little O-rings (5.5mmx3mm) that are required to keep oil from being pushed up these abandoned studs and out the openings in the head (again unique to the 77/78 F model). SURELY this must have been the issue, so the engine goes back in, only to be blessed with my shin bathed in hot oil yet again!
Soooo.... after pulling the engine for the THIRD TIME, with the engine on the stand, after removing the cam and cradles, staring at the top of the head while contemplating removing the head YET AGAIN, I happened to notice that one of the cam bearing bolt holes was not filling up with oil (lots of oil puddles in the top end).
Now one side of the bearing cap uses a stud, the other side uses the bolt. Interesting thing about those cam bearing caps is that the stud that is used on one side of the cap have "bottomless" holes where they thread into the head (i.e. they go all the way through and are exposed to the atmosphere in the cavity above the spark plug well). These studs typically require thread sealer if they are removed in order to prevent oil from weeping past the threads.
Okay, enough about the studs, we are talking about the bolt side of the bearing cap (towards the rear of the cap). Took me a while to wrap my head around how the oil flows through the cam tower to the bearing. First of all, these bolt holes are not supposed to be bottomless. Apparently a P.O. had used the cam TOWER bolt where the cam BEARING CAP bolt should have been used (the tower bolt is a little longer than the bearing cap bolt). Being a curious sort, I grabbed my little squirt can of oil and squirted oil into this bolt hole, only to see that oil appear in the head cavity below, exposed to the atmosphere, in the vicinity of the head nut under the "coin" rubber puck under the cam tower. Apparently some goob of a P.O. used the cradle bolt in place of the bearing cap bolt punching through the casting! Crank down on it hard enough and it can "punch through" the casting, exposing this bolt hole to the atmosphere as well. Upon closer inspection of the cam tower, where this bolt passes through on its way to the threads down in the head, you will see that the oil feed for this cam bearing passes through this bolt bore. This bolt has oil under pressure behind it!
Pour some oil down these bolt holes and see if these holes will hold oil (i.e. bottom of bolt hole still intact). If any of these holes do not hold oil, then these threads will now require thread sealer, unless you prefer copious amounts of hot oil spewing out onto your shin while you ride, because that's what mine was doing to me. After careful consideration of what I had found I narrowed my options down to two solutions:
1) Gob up the bolt with thread sealer, bolt it back together, and call it done. Two problems with this solution were the possibility of thread sealer getting scraped off the bolt as it passes by the oil feed hole in the cam tower that passes through this bolt bore, potentially packing this oil feed with thread sealer and starving the cam bearing of oil.... not good. The other drawback to this solution (if you can get it bolted back together without plugging the oil feed) was how is the next guy supposed to know that these threads require sealer? They won't, and after some future disassembly/cleaning/reassembly, this new owner is then trying to chase down this inadvertent major oil leak.
2) The solution I finally settled upon was to use a threaded stud with a nut at this location also. This permitted me to use liberal amounts of thread sealer without fear of plugging the oil feed passage by removing the cam and cam tower before installing the stud. This made installation of the cam a little tighter than usual since the bearing cap I was dealing with was the one on the sprocket side of the cam chain tunnel. It was a little tight but far from impossible, there is no need to remove this stud during future teardowns (except for top of head resurfacing), and if the stud were ever removed, hopefully that future owner might think to themselves "why'd they do that" (use a stud in place of a bolt)?
By all means check for this potential condition, especially since it isn't supposed to exist! If I hadn't seen it for myself I never would have believed it.
Best of luck and keep us posted.
