Hi Victor Enthusiasts -
I have recently purchased a'67 Victor Special round barrel, not running. After a performing a basic maintenance once over, replacing a cracked coil, doing a carb rebuild, and adding a new plug, she started right up! Although seemingly running well, the N4 plug color was much too sooty. Doing further research into this bike I find that the plug recommended for that year was N6Y. The 69-70 models used the N4.
So, why the change to cooler plugs in the newer models?
FYI - newer models were also equipped with a battery, ran a bigger carburetor main jet, had a lower needle position, and also had a longer exhaust.
Did you check the timing? Retarded timing can result in a sooty plug too.
I think the plug change was mid season. Below parts bulletin from October 1967 change 10768 says B44 Roadster but I suspect it applied to the VS also. Why the change I don't know.
Interesting, although the 66-68 service manual does not reflect the change with the Special.