Unknown Engine needs new spark plug

Hi Folks,

I recently purchased this locomotive with an engine that appears to be from an old moped or motorbike - it's two stroke with an integrated 2-speed gearbox and what appears to be a decompression valve on the top to kill it.

Does anyone know what it is, or how I might find out? I need to get a new spark plug as the previous owner forgot to put it back in, woops!

I can't provide much more information sorry, the spark plug thread appears to be 12mm based on measurement. I've looked all over it but can't find any badge or logo from the original manufacturer, although i did find a serial number if that would help

As you say, not a lot of information. 12mm is a fairly standard thread. The other important measurement is the thread length. If you can measure this then look on some European moped websites you may find something that will work.

The make of the carburettor, and number if visible, might at least help identify the country of origin.

If the engine was built between around 1950 and 1965(?) Newnes Motorcycle Data Book may help as this gives basic specification and service data for most of the motorcycles, scooters, mopeds and light cars sold in theUK over that period. Including carburettor make and number.

My copy is of the second edition which only goes up to 1961, I think there was third edition with a later cut-off date. It's fairly comprehensive, covering some makes I've never seen or heard of elsewhere.

Clive

There was a moped engine with a 2 speed gearbox, Mobylette or Motobecane, maybe. I am surprised that the plug is 12mm, though, back in the days it was 14 and 18mm and the first use of 10 and 12mm plugs was by Honda which was a novelty at the time. The approximate bore sizes of the plug thread in the head would be 10.4mm for 12mm and 12.5mm for 14mm.

Hi all, thanks for the information that's super helpful

mart: yes i think i've mis-measured, the thread INSIDE diameter was 12.4mm which would make it an m14 thread

roger: measuring the thread it appears to be around 10mm so will see what i can find

clive: the carburettor is made by "bing", but i'm fairly confident that it is not the original carb - it's tricky to make out in the photos but it's being held away from the engine block by lump of steel about an inch long, doesn't look very factory!

This looks to be a remarkably useful site for information: **LINK**

https://www.myronsmopeds.com

MichaelG.

NSU Quickly.

NSU Quickly.

I only know of two mopeds with a 2 speed gearbox. Quickly and Mercette. My Mercette used a 4 stroke OHV engine.

If it is indeed an NSU Quickly motor there are specialists in the net for these things. Google "nsu quickly Zündkerze" and it will throw up a Bosch spark plug.

+1 for NSU Quickly.

Newnes says:-

Bosch W240T11 plug, breaker gap 12 thou, timing 24° btdc,

Carburettor Bing 1/9/1, main jet 56, needle position 2.

Shedloads of information on the internet.

Clive

Edited By Clive Foster on 16/06/2023 23:24:15

it absolutely is a Quickly, thank you very much I didn't expect to get an answer so quickly. The previous owner did tell me the name but I misheard it as "LSU" which would explain why I couldn't find that!

Deleted.

Edited By Robert Atkinson 2 on 17/06/2023 10:26:52

So it is an NSU engine, my friend had one for a while and we shoehorned the carburettor from a Villiers Midget lawnmower engine onto a home made manifold for it. The beast would go nearly 40 mph. One interesting thing about that motor was the chrome bore in the aluminium cylinder, his was worn right through over about 20% of the surface and it still ran.