Hello all what spark plug does everyone recommend in my bsa b40 running electrex works ignition?

Many thanks

 

Electronic ignition or not I think it has no major impact. Start with what is recommended for B40 trials riding.

You may find some answer here http://www.bsaotter.com

Think electrex is delivered with correct cap.

Remember that modern petrol doesn´t foul plug as much as before. Long time running may be necessary before reading plugs. If black colour after short time it might be oil contamination and it hasn´t much to do with spark plug grade, but oil taking part in the combustion process and it should generally be avoided.

 

 

Many thanks I Carl would you know what the standard plug is?

 

Many thanks

 

 

 

 

 

 

 

 

 

 

 

BP5ES is good, 4's are better if you can find them.

Rupert Ratio "Unit Single Manual" states for 1962 bikes.... N5. I would try a projected N11YC or even N12YC and see how it goes. Projected spark plugs must not bang into something (piston or valves) N5 is non projected as normal of that day. Think N5 would equal N9 projected, or just about. A plonking trials bike may need a little hotter plug. Do not replace original Electrex cap. It might sit there for a reason (suppression)

2 hours ago, b40rt said:

BP5ES is good, 4's are better if you can find them.

Used on 1967 WD B40.

On 1/27/2023 at 11:12 AM, b40rt said:

Used on 1967 WD B40.

Thanks b40rt