Quad Polsten spark plug?

Originally posted by tyler1
As the title says, it's off my Quad polsten, but its knackard, does anyone know if there's a modern equivilent?

The only markings are 6-M and its a Champion.

You'd probably need to look at one in the motor factors but translating your picture to the NGK codes:
http://www.spark-plugs.co.uk/pages/technical/ngkjpg.htm
you have a 14mm thread of about 10mm length, taper seat and short insulator. This would equate to a BM6F I think.

Having spoken to a NGK rep recently, he advised that the huge range of older plugs are now replaced with one equivalent because of material advances. Just about everything has a heat rating of 6 and the other differences are mechanical.

R.