Topic: CB350 K3: do I need to replace the base gasket now?

[Tugboat]

Had to remove the head last night on this CB350 to fix a stripped-out spark plug hole (not me!!). When I was wiggling the head to break it free from the jugs, I noticed that the cylinders were also pulling free at the bottom. I’m not planning on pulling the cylinders to avoid having to hone them and install new rings. By disturbing the base gasket, am I asking for leaks if I just button the whole thing back up? Or do I need to pull the cylinders now and replace that gasket?

[70CB750]

Tough question.

Did the base gasket get torn?  Or just loose?

But if you don't replace rings, you don't have to hon cylinders.  Honning is for seating of new rings. 

That said, I would pull jugs off, replace the gasket and put jugs back on.  Gaskets are cheap and it may save you some frustration in long run.

[grcamna2]

If you decide to pull the jugs off to put a fresh cyl. base gasket down(I would)please be careful to keep an eye out for the cam chain roller assm. that sits in the center channel between the cylinders,it has 2 little half moon rubber thingys that keep tension on the lower roller shaft so it stays centered correctly & tightly between the two cutouts in the crankcase .I pulled my cylinders right off w/ one motion and one of the little rubber buggers fell right down inside the lower cases & I had to "find"another one before assembly  . The good part was that the little rubber tens./holder came right out at the next oil change  The other thing to do when you pull the cylinders is check the condition of those 2 cam chain rollers & see if the rubber is starting to pull apart.There is a seller on Ebay w/ the name "Pawelzack" in Poland.He sells excellent quality replacement cam chain rollers that will last a LONG while.

Tug,if you decide not to replace the(original?)lower cyl. base gasket it'll weep a little bit of oil & not be too much of a problem...;but if it's the original one from 40 yrs. ago I would replace it along w/ the cam chain rollers & a new cam chain.