Help/Advice on muffler installation '84 CB700s

[Stu]

Hi Guys,

This is my first post to the forum, so apologies if everything isn't formatted correctly.

I removed my mufflers to clean and repaint, and I noticed a bunch of black, sooty build-up where the four pipes join the engine. See Pictures, I shined a flashlight to try to show build-up better:



I feel like I should clean this build-up, but I'm worried about crud falling back into engine compartment.  I'm not a good enough mechanic to take apart the engine and seal off engine compartment from the inside.  Any Ideas on how I should address this build-up?

Also, I've ordered new copper compression gaskets for re-install, which went fine the first time I did this several years ago. This time the old copper rings seem pretty smashed in there.  Any advice on at least removing old rings?

Thanks!

[mollusc]

Try a dental pick to get the old copper out of there.  You do usually have to dig around a bit.
As far as cleaning goes, I would stuff a shop cloth in the exhaust port to stop stuff getting in.  Avoid using a regular paper towel if possible because they tend to tear and leave pieces behind (not that it should matter too much in the end).
The last pic looks like you may have a leak from your camshaft cover gasket.  If you don't deal with that, you're only going to get oily again.  The gasket from the 1996-2003 CB750 will fit.  You'll also need to replace the rubber washers that fit on the bolts that hold down the cover.