Topic: Barrel seal differences help please...

[Paul Lowe]

Am rebuilding what is a K1 as per engine numbers. The old barrel was poor so bought a low miles K0 barrel and pistons (so I was told).
Looking at manual and parts book it say K2 had metal pins and seal in between barrel and head for inner head bolt locations.
Both the heads I have show a place for these steel pins and my gasket kit (generic ) has little rubber tube type seals.
Based on pics can someone confirm K0 K1 barrels had these type holes or have I got K2?
Depending on answer do I need to worry about having these or just the two o-rings on centre rear stud?

Confused

[bjbuchanan]

You use just o-rings on the inner parts of the head. The longer tube type seals come in later models to help try to kill the head gasket leaks. They have way more dowels and make a lot more sense as to where the tubes go.

[Kevin D]

Service bulletin #42 describes the leak problem and the differences between the early and late cylinders. I tried to get the service parts offered for my flat decked cylinder but was told they are no longer available.

http://manuals.sohc4.net/CB750SB/750_42.pdf

Your photo shows a K2 or later cylinder, with counter bored stud holes.

[Paul Lowe]

Thanks for responses.

Hmm was assured the barrel was K0!

Since it has the dowel holes bored can/should I use them to help prevent leaks?  Is the head different between K0/1 and K2?

Don't want to remove engine again later but also won't be doing a lot if miles in it.

[bjbuchanan]

You can choose, if you don't run the tubes it is no biggie. The important one is the two prongs at the back. There is debate as to whether or not the tubes rly did anything

[flybox1]

I omitted the barrels.  No leaks so far.

[Paul Lowe]

Thanks so far. I figure the two input seals are high pressure and most critical where the return paths are low pressure. Thoughts?

Can anyone show pic of K1/2 barrel to show difference in this part?

Great to have such help when I'm in the shed scratching my head!

[Kevin D]

I figure the two input seals are high pressure and most critical where the return paths are low pressure.

That's correct. Pump pressure at two rear center, gravity return to crankcase at 8 studs with/without tube seals.

Have you visited the manuals section? Check the lube flow diagram there. Sorry I dont have pics, hard drive crash.
http://www.sohc4.net/cb750k-manuals/