Carbon Buildup Issue

A set of intake titanium intake valves with less than 4000 miles on them -



Close up of a couple of the worst ones -



And the head, which was not really that bad -



Yamaha makes a fuel additive ("Ring Free") that prevents this from happening. It can also be used in a higher dose to remove it.

My wife has a Ford Windstar that has 130,000 miles on it - knocked and pinged all the time, even with premium - first dose of Ring Free eliminated the knocking and pinging.

When using the higher dose, you are supposed to change the oil/filter and spark plugs.

I'll change the oil on the Windstar, those rear plugs are "well placed".