The blue color would only be present in the exhaust, since it is a
result of oil being *burned*. Somehow, oil (and quite a bit of it) is
getting into the combustion chambers.
Some thoughts:
Take a look at the inside of the carbs and manifold. If there is an
oily film there, you're sucking it in through the crankcase breather.
If not, it's either getting past the rings or the valve guides.
What kind of oil did you use during the break-in period? When did you
change it?
How much of an overbore? Are you *sure* you've got the correct pistons
and rings to match the overbore? (I hesitate to suggest it, but as
someone else said, sometimes mistakes are made.)
Run a compression test.
Guy Weller wrote:
>
> OK, here are some more accurate checks on the problem:
>
> Steady tick over at 800rpm.
> Slight blue colour to exhaust. If run in garage it soon becomes
> uninhabitable (as does the kitchen and the whole of the rest of the
> house 'cos there is an interconnecting door which isn't fume proof) -
> not popular with "her indoors".
> No revs change when I remove oil filler cap. very slight, I mean only
> just detectable with the help of imagination, positive pressure at oil
> filler cap.
> Steady stream of air from end of disconnected crank vent hose, can
> feel it against my face, but no colour in it - i.e not blue even when
> directed across white paper.
>
> When I blip throttle there is a good belch of exhaust, quite blue but
> also whitish cloud. (but it is not steam!) Oily smell.
>
> Definately consuming oil, about 1/2 pint per 300 miles I would guess.
>
> Remember, rebore, new pistons and rings 3000 miles ago.
> Reconditioned head with new valves and valve guides this weekend
>
> Guy
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