Tiger T100s 500cc engine knock

[T100striumph]

Hi all,
On the way to work today 10 mile trip, my bike developed a deep thumping noise, sounds like bottom end under acceleration. Have owned 51 years so used to all the normal noises. Any ideas would be welcome before I start a complete strip down.
Nev in NZ

[R]

sounds like bottom end under acceleration.

We think you have hit it in one ?
Drain the oil, and see if any debris comes out.
Big end shells in particular.

51 years is pretty good service. ?
Have fun !

[iansoady]

Does it have the bronze timing side bush or ball bearing?

[Rex]

My old T100S had the plain bush main bearing. I think it was a model designation which only lasted from 1967 to the 1970 model year.

[Barryhill8]

The engine, finally found the number, is a Villiers 147cc 30C. Does anybody know what spark plug to use?

[Rex]

probably get more replies if you start a new thread about Villiers spark plugs?

[Rex]

So, how did the 500S engine knock turn out, or even the Villiers spark plug?