back history: bought a used 1999 zx-9 with 30K on the odo. dont know the service history but it had a clean title and previous owner was pretty diligent about regular oil changes and such. have a kerker exhaust (which has no baffles to create back pressure, pretty much a straight shot can only and is more for noise than performance). has BMC high flow air filter installed as well. dont know if the bike was rejetted or syced for the filter/exhaust. always run chevron 94 and did a recent seafoam stabilization for the fuel (but run the bike every week just cause i cant stop listening to it purr)
pulled the plugs. the threads and the plug tip has a very dark but light layer (not thick or carbonized) of oil on it. i wiped off the oil and the plugs look brand new (no carbonization or burned up areas), other than the black oil over em.
i think im running too rich because of the lack of rejetting with the exhaust. are there long term effects of running too rich (other than bad fuel milage and fouled plugs)? i heard if you run too lean you could fuck your engine for good. but what about running to rich? or maybe the oily plugs are from something else. comments? thanks guys/gals.