441 Victor Spark Plug Evolution?

[Big Diehl]

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.

[limeyrob]

Did you check the timing? Retarded timing can result in a sooty plug too.

[JulianS]

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.

[Big Diehl]

Interesting, although the 66-68 service manual does not reflect the change with the Special.