As for the carbon/deposit issue...ALL gassers have deposits...just check your
spark plugs...they will all have a coating of deposits of some sort
Turtle is again spot on and one of his comments telling of one aspect (to me)
Over-lap and if there is any back-flow...telling to me that the exhaust is NOT
scavenging well enough for that amount of over lap...or the swirl designed in is
going in the wrong direction. A good head tool and die grinder person should
know HOW2 manage that...but...they can only do with whatever material the OEM
has cast into the CC
Another potential cause is that the valve timing to the piston exhaust stroke
has the intake open too early...but that goes again to the scavenging of the
exhaust system.
Do note that with a turbo, scavenging is tougher to manage, but it still can be...especially
by the OEM...who had a clean sheet during design architecture...
There are many, many factors in just that and the OEMs has a much better picture
than us on the outside (normally) as they have the whole and total specification
along with test data...
Turtle...thanks for educating me on a two injector system...now there
will be some fuel in there during the initial compression stroke and
very lean to boot...meaning that there is now pre-ignition potential
that was NOT there with one DI injector...