Spark Plugs

Hi can anyone tell me what spark plugs should be in the 400cc engine. Cheers Chris

Hallo Cliffy,
Chapter 5 of "Learn Your ABC" in 'Articles' could give you some ideas. But really, the ABC isn't fussy.

Further to my words to Cliffy, the following:-

Sparking plugs have come a long way since 1920. In those days there were more than 100 makers and types in the market, some of them quite good, some of them really weird, but nearly all claiming to be THE BEST! In fact, a lot of them, very clearly, were fairly dismal!
I have examples with mica insulators (which weren't compatible with leaded petrol when that came along) and with spiral electrodes that were claimed to burn away without changing the spark gap. I saw a 'plug once with its own built-in priming cock!
If what you want is a SHOW bike, then go for period 'plugs.
But if you want a GO bike, better fit modern!