dps650rider
XS650 Addict
Looking for some opinions on these spark plug pics from the right cylinder. Plug is black on the intake valve side and white on the other side. Left plug looks normal but a tad rich. Bike runs great with a fresh bore job, pistons, rings and valve seals. Valve stem to guide clearance was in spec when I put it together and compression is good in both cylinders at around 150 psi. At the start of the season plugs were good but this seems to have gotten progressively worse. Never see any oil smoke and exhaust smells clean if I give it some revs. Seems like it must be a valve seal problem but they only have about 2500 miles on them.