New pushrod tubes needed?

[montmil]

... So the question now is, sealant on the cylinder base and head gasket or not ?  If so which product? I have hymolar but it's brush on.

Do the cylinders on your '79 R65 have the large o-rings? If so, technically, you don't need any jug-to-case sealant. Should you elect to use a sealant, and YamaBond is a good choice, use a dab about the size of a small fingernail. An almost translucent smear is adequate. Avoid excess sealant around the upper case studs as these are oil passages for the rocker assemblies. And don't forget the two small o-rings per jug.

[Barry]

A 79 model should have the cylinder base O rings.

[79beem]

Yep, I have base and upper stud o-rings.

Chris Harris doesn't use any goop on the cylinder base with o-ring types.

What about with the head gasket?
Necessary or overkill?

[Matt Chapter]

What about with the head gasket?
Necessary or overkill?

Negatory on the goopy head gasket.  One side is stickum, make sure you get that side going the right way.

[montmil]

Yep, I have base and upper stud o-rings.

Chris Harris doesn't use any goop on the cylinder base with o-ring types.

I would not recommend Chris Harris as an ultimate Airhead authority. Some of his videos and tech tips are way off base. Both Oak and Snowbum agree that even with the base o-ring, a little sealant is not a bad thing. Your call.

[Bob_Roller]

Is cylinder base oil leakage a common condition

I've replaced the cylinder base O-rings twice since owning my '81 R65, in '98 and 2014 .

Both times, I had the heads off and thought it was wise to replace them while I had the opportunity, only took an hour to do both cylinders each time .

[nhmaf]

Odd that you felt the aluminum temps were lower than the silver solder temps - I used common copper pipe soldering and flux, with a melting point of about 400C.
I have some aluminum solder for brazing - it doesn't melt until well over 600C.    Had no issues at all with the silver solder on the OEM tubes - just have to make sure that they are scrubbed clean and properly fluxed, though, or the solder won't stick.

Hylomar works fine, but I'm a convert to the more easily obtained Yamabond now.  As others have said, technically you shouldn't need it with the base o ring cylinders, though I suppose you could CAREFULLY put a VERY light amount on areas that are not going to be near the O-rings or cause excess sealant to squeeze into the O-ring's groove.

Definitely no goop on the head gasket - you'll notice they are slightly asymmetrical with respect to the lower 6oclock stud hole and the pushrod tubes - they will only go on one way, or else it is likely that the headgasket will be rubbing on the pushrod when the engine is assembled and running.

[montmil]

Here's all the YamaBond you'll need for the jug to case:

[montmil]

... Definitely no goop on the head gasket - you'll notice they are slightly asymmetrical with respect to the lower 6oclock stud hole and the pushrod tubes - they will only go on one way, or else it is likely that the headgasket will be rubbing on the pushrod when the engine is assembled and running.

Lettering on the head gasket faces [size=12]out[/size], i.e.: toward the head and toward you while facing the cylinder. Confirm pushrod passages through the head gasket are centered over the pushrod tube openings.