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.

[Big Diehl]

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

Yes, but I will give the timing another look. It wouldn't be the first time I got that wrong.

[limeyrob]

I suggested it because I had a similar issue with a Matchless single, timing had slipped and I was chasing a rich mixture that didn't exist. It also benefitted from a hotter plug and I did read somewhere that modern petrol can soot plugs because it has additives to prevent combustion in high pressure injection systems.  I'd like to track down the source in case that's nonsense!

[scifi]

Have you changed your cool N4 to the hotter N6Y,?   It should clear some of the soot.

I used to have a Rover 6 cylinder car, that used N5 plugs, but cylinder 5 was oily and needed an N8.

Edit.....   My mistake..  the N6Y is not hotter, it is the extended tip version, which may or not foul the piston.
              So maybe try the N5 or even N6, to get a hotter plug.

[Big Diehl]

I had a heck of a time finding N6Ys. Found some on eBay and I am waiting for delivery. Meanwhile I am traveling so I will let everyone know about the results.  I did find this in the 67 owner's manual:

[limeyrob]

Having had a run of plug problems with my Road Rocket I recently changed to  Denso W20ES-U at the recommendation of SRM.  These have fixed all the issue and were not pricy.  Equivalent to a B7ES

[Big Diehl]

Found this old spark plug equivalent chart. Looks like, for the N6Y, B8ES is the correct equivalent. These are also hard to find without resistors (BR8ES).

[Big Diehl]

Actually, it calls for a BE8ES, no clue what the first E is for? I can find reference to the second E, but nothing that explains that letter. That doesn't matter though since they are nowhere to be found on the web.

[Big Diehl]

Having had a run of plug problems with my Road Rocket I recently changed to  Denso W20ES-U at the recommendation of SRM.  These have fixed all the issue and were not pricy.  Equivalent to a B7ES

Noted! Thank you, if the N6Ys don't do the trick, I will look for the Denso equivalent you listed.

[Andy Kay]

I am currently using the NGK B7ES with no problems on my 68 Victor Special.
As for carburation, it's a minefield, the owners handbook gives different jet sizes and needle position to the workshop manual. The jets and throttle cut out alters for every year model and is different to the B44 roadster.
On top of all that the jets and needle position actually in the carburettor didn't match exactly to any of the information given.
Even so the old girl runs fine.

[Big Diehl]

I am currently using the NGK B7ES with no problems on my 68 Victor Special.
As for carburation, it's a minefield, the owners handbook gives different jet sizes and needle position to the workshop manual. The jets and throttle cut out alters for every year model and is different to the B44 roadster.
On top of all that the jets and needle position actually in the carburettor didn't match exactly to any of the information given.
Even so the old girl runs fine.

Thanks for the input Andy.  I would gladly try the B7ES however, they seem to be rare without resistors. I ordered a couple from Amazon, and what arrived was BR7ES. I sent them back. Does NGK even make non-resistor standard plugs anymore?

[rhyatt]

Has anyone explored BISK plugs.
I've heard they're good and a good heat range.