KLG L777 spark plug

[Greenfield]

Has anyone got any suggestions for a modern equivalent spark plug for the old KLG L777 fitted to many BSAs in the 30s?
Would a Champion L87 do the job?
Cheers

[militaryron]

The real modern equivalent is Champion L82C but I've been getting better results (Less failures) with Bosch W8AC. Both available from the "Green Spark Plug Co" quite cheaply. I've also bought NOS original KLG F70 and Lodge C14 on ebay, but more expensive of course.

I have a couple of those lovely KLG L777, brand new in their tins, and their special plug caps,  I just keep them for display. Ron

[courtney]

There's a good alternative list at this link below that may be helpful.

https://www.nortonownersclub.org/sites/default/files/2021-09/KLG%20Lodge%20Spark%20Plug%20Chart.pdf

Lodge H14 may be ok and there is one for sale here reasonably: https://www.lmslichfieldltd.com/H14-Spark-plug-Lodge

I'd look for NOS old plugs or even good used ones. You'd probably have some luck at a jumble if there's any local to you.

I found Bosch to be the best of the modern equivalents. However, I put the old KLG K1, which must be as old as my bike, back on my bike (a B2) and it starts and runs better than any modern equivalent.

[Greenfield]

Many thanks
When I got a new bike/car in the past the first thing I would do was to change the oils, plugs, points and filters etc before I drove them. Unfortunately in recent years I have found that replacement plugs have sometimes failed after a year of little mileage and have resorted to putting the old plug back in. You wouldn't think that there was much to wear out in a spark plug apart from the electrodes after thousands of miles.
I'm gradually working my way through the B21 and of course it's fitted with the wrong plug. It will be renewed.

[courtney]

I read something about it being the unglazed insulation of modern plugs not being ideal for old vehicles and rich starting and running conditions. Once they're fouled up a bit, they're junk most of the time.

For some reason, one of the first things I did was remove the old KLG and put a modern Champion one in, but it was rubbish. Hard to start when hot and from cold after tickling. Also tried NGK and Bosch. After reading up, I thought I'd put the old one in and it has been faultless.

[militaryron]

The old insulators were proper Porcelain. Modern plugs are little more than chalk it seems. Ron