Topic: 'Decoking' a CB550

[Brian G]

...also known as 'decarbonising' on this side of the pond 

The BSA shop manual for my Rocket 3 notes:

Always leave a ring of carbon round the edge of the piston crown and do not remove the ring of carbon at the top of the cylinder bore (see Fig. B11)

BSA 1969 A75R Service Manual, Pp. B13

I've never seen this in a Honda manual and since I have the head and barrel off of my 550 I'm wondering whether to scape everything off or to follow the advice of Birmingham Small Arms. They must have had a reason for making the statement - OTOH, they are no longer in business   

Thanks,
Brian

[bucky katt]

when i would find that carbon build up at the top of a cylinder i would hit it with some Hoppes #9 gun oil, i always have a bunch of the stuff around and it really eats away the carbon fouling. i've built many many different kinds of motors and i have always removed carbon build up, though i would never use mecahnical force to do it, except maybe for a wood paint sttirrer after a solvent has sat on the deposits.

[bryanj]

If it don't wipe of with a cloth leave it there

[MCRider]

If it don't wipe of with a cloth leave it there

Would it be fair to say it depends on what you are doing? If its a teardown to fix an oil leak and nothing else, then leave it alone? But if you're re ringing it and lightly honing, its going to be hard to avoid removing those carbon bands.