[Spitting Bull]

Hi slider - these are just thoughts - I'm not speaking as an expert here!  

Nowadays most of us are leisure motorcyclists who take a great pride in their bikes.  We have much more time for maintenance and I think that's part of the fun.  If my rear brakes squeal a little I'll remove the wheel to find out why. But years ago, people who needed their bikes every day to ride to work wouldn't have done that until the brakes squealed a lot.

If my bike begins taking five kicks to start it instead of one, I'll be looking at the carburetter, the plug, the points etc. etc.  The all-weather, every day riders would have just come out of the house a little earlier.  

(Of course this is a generalisation.  Not every rider is a leisure-rider, and there will be modern riders for whom the bike is an essental means of transport, and they can't leave it in pieces overnight as they will need it next day.  But years ago, more people were in that position).

If your bike was running too rich, or especially if it was burning oil, you could get away with it for a long time by taking off the head every now and again and scraping off the excess carbon.  It was quicker and cheaper than fitting a new piston and rings, and the bike stayed on the road ready for work.

We tend not to let faults get worse and worse until they become serious.  As long as our ordinary maintenance means that our bikes aren't running too rich and aren't burning oil, then I'd think there shouldn't be enough carbon build-up to require scraping off.

Of course, if you need to take the head off for any other reason (valves, gasket) it makes sense to look at carbon-build-up while you're at it.  But I do think that it probably needn't be a regular part of motorcycle ownership these days - mostly due to the way we use our bikes.

Tom