Rocker box sealing questions

[GLJ]

Starting to assemble my engine. I've read through Jim's excellent thread on top ends. But I have a couple of questions. When applying sealer to the head for the rocker box there is no sealer around the 4 studs in the middle of the head. I'm wondering why? I've torn down 2 engines and both show evidence of having sealer there. Does anyone know of a reason not to? Last question is Yamabond 4 the a correct sealer for this application?

 

[Jim]

Does anyone know of a reason not to?

Doesn't hurt if you want to, but it's not necessary... there's no way oil can work it's way up the studs. If it gives you a warm fuzzy.... go for it.

Can't help you on the sealant.... I'm a Permatex fan.

 

[Signal]

I have been using Yamabond 4.
I believe 4 could make it more difficult to disassemble but have had no problems splitting cases etc using the 4.
Yamabond 4 has an equivalant Threebond 1104.
http://650central.com/
Scroll down the page to find threebond. MMM uses it enough said.
What is the sealer in your photo ?

 

[GLJ]

What is the sealer in your photo ?

The pic was Jim's. I believe it is Permatex.

 

[Jim]

Yeah... Permatex Aviation sealant.

 

[5twins]

I always put sealer on those center spots for the very reason you stated - Yamaha did originally. I don't know if it's really needed there but they did it so I do too. I apply the sealer with a trimmed down acid flux brush. Basically, I "paint" it on the surface, spreading a thin, even coat over all of it.

 

[TwoManyXS1Bs]

I always put sealer on those center spots ...

Crankcase venting pressures can push oil into those zones...