I put new spark plugs in my bike last year and they have only ran about 6000 miles. Took a notion to pull one out and compare the new to the old. The old ones were still working fine but I decided to replace them when I did the valve check and antifreeze change. The porcelain on the old plugs were slightly a brownish tinge. The new plugs are still white. Is that normal? I would have thought they would have changed color a bit. Bike is still running the same, start good, and fuel mileage is the ssme. Only thing different is I replaced the original paper air filter with an oiled one which was the same size. Just wondering if it is getting more air flow and thus running leaner.