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by Mal Marsden - 06/16/22 7:00 pm
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Allan G, Gary Caines, Gordon Gray, Hillbilly bike, kommando, ned37, SpeedyV
Total Likes: 12
Original Post (Thread Starter)
by Gary Caines
Gary Caines
I have a newly acquired 1969 BSA 441 Victor Special. The manual calls for a Champion N4 spark plug. I've looked at several references that say that a Champion N4-C is not compatible with my engine. Years ago I had a BSA Gold Star and I had difficulties with Champion plugs going open internally, I'm assuming from vibration. I also burned a hole in a piston in a 74 Trident I had, apparently from too hot a plug. I finally had the best luck with NGK plugs holding up in my Gold Star. I also had good luck with Autolite plugs. What is the best plug to use in my 441 Victor? I have read a considerable amount of conflicting information.
Liked Replies
by Allan G
Allan G
Where did you read that the N4C wasn’t compatible? The standard N4 is no longer available and the N4C is the direct (C meaning copper core) replacement.

The N4 part of N4C is dimensionally and heat range identical to the old N4.
3 members like this
by kommando
I have run projected spark plugs in Unit Singles for 40 years (C15,B25,B40,B44), never had a hole in a piston or the gap close up.
2 members like this
by LarryLebel
1 member likes this
by kommando
Don't expect ebay seller databases to properly cover an over 50 year old motorcycles. As Allan says the N4-C was a direct replacement for the N4 with a copper core, it can hardly be incompatible with a B44. My B44 is twin plugged so no point in giving you my plug numbers as its non standard in that and a few other ways.
1 member likes this
by Gordon Gray
Gordon Gray
Originally Posted by LarryLebel

I should know better than say anything but that’s hard for me to do.

Larry’s plug is 3 heat ranges hotter (?) than the plug I use. Unlike kommandos bike mine are all pretty much stock.

This darn “no longer produced” stuff with plugs is a pain. I’ve been doing some research today and I’m getting conflicting information on the plug cross overs.

It used to be simple.

1 member likes this
by quinten
[Linked Image from]
1 member likes this
by Shane in Oz
Shane in Oz
Originally Posted by Gordon Gray
Site I used ( today) clearly says BOTH the B8 and B7 are replacements for N4. How can that be?

Confused in NC…….I knew better.


Originally Posted by Allan G
I have a bsa article somewhere which kinda agrees with your B8ES =N4, though modern cross references say different. In this particular article it goes on to show the N3 equivalent is equal to B9ES.
Apparently NGK and Champion spark plug numbers are about half a heat range offset from each other+ as well as running in opposite direction, so the Champion N4 is about an NGK B7.5E* and the N3 is B8.5E*. Alternatively, an NGK B8E* is about a Champion N3.5 and the B7E* is about a Champion N4.5.

Just in case we weren't confused enough already, Champion's 'N' is 14mm, 3/4" reach (yes, they really do mix metric and imperial), NGK's 'B' prefix is 14mm and 'E' suffix is 3/4" reach

[+] I read that years ago, but don't remember where, or even if the source was trustworthy. Take it with the appropriate sized grain of salt.
1 member likes this
by Richrd
Just to confuse Gordon even more, ngk no longer makes non resister plugs.

Try to order a b7es or bp7s and see what you get
1 member likes this
by Gary Caines
Gary Caines
I'll come look you up. I'm a member of GABMA and I've been going to British In The Blue Ridge for over 20 years now. I only live about 10 miles east of Hiawassee on 40 acres in the middle of the woods. I'll likely be riding my 68 Triumph Bonneville. My cell is 706-994-5704. Looking forward to exchanging tales. The BIBR rally is really good and they even give away a motorcycle in a drawing. This year it's a 1969 Triumph Bonneville.
1 member likes this
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