What can this mean my bike has 49,000 miles on it. It sputtered a little bit today after riding on the freeway for an hour after I was slowing down. Brought the bike home check the plugs Found a little bit of what could be or oil Or maybe on Burnet gas dark in color On 1 side of the spark plug threads. The electrode look perfect. After I seafoamed in the vacuum lines and clean the carbs the bike pulled hard in every year

 

First off, wow 49,000 miles and still running strong. Very happy to hear that.

Could be valve cover gasket leaking. I've also heard of unburnt gas getting on threads. It's most likely valve cover gasket starting to leak though. If it acts up again then you might want to look into it.

 

Is there any sign of blue smoke coming out of the silencer whilst you are riding along? If so, this could be worn valve guides or piston rings and would account for the oil on the spark plug threads, but if the bike is performing really well, then I wouldn't worry too much. If you have a compression tester you could test the compression on each cylinder and compare the results to see if any are down. To test for oil ring wear you pour a teaspoonful of oil into each cylinder in turn and check the compression figures again. If the pressure goes up then this would indicate piston ring wear if there is no difference but the pressures are down then this could be that the valve clearances are too tight, not allowing the valves to close fully. Oil on the spark plug threads is probably due to valve guide wear if the above test proves good cylinder pressure(s).

 

Thanks for all the feedback I really do appreciate it. the bike has absolutely no signs of smoke coming out of it. It really does drive well for his age and mileage however recently it started to sputter a little bit After I have it on the freeway for a while to come to a stop. the RPM's drop down and putting it back in first gear and pulling away from a stop it feels like it's going to die however it does it intermittently. And once you get past that point it pulls really strong through all of the gears. I treated it with seafoam in the carbs and a good blow out a lot of smoke then but that's the only time I'm going to check the vacuum lines but my feeling is that it's a carb related issue. I'll keep you posted as I Go through the bike