Early Jap industrial engines

Having owned and worked on a great number of Jap industrial engines over the last 40 years I am wondering how many really early examples remain. The A to Z puts the start date of manufacture at about 1937, we know this to be incorrect as the 4/2 was the first engine into production in late 1934. This was followed by the Jap 5 then the 4/3 and the 6. The twin cylinder 55 was the last to be introduced. I have seen several jap 2as with 1936 stamped in the air case.
So if you have an old Jap sitting about take a look at its engine number. The oldest models as said above are the 4/2. Very early examples have a cast iron construction and a 3 part air cowl.
Lets see if we can uncover some early models.

Regards

D.Riley.

I'll start us off with my all cast iron 4/2 bought locally but with no history.
P15904 UVX (1940?) Been worked on in it's past as it is now bored +.040. It has pins through valve stems instead of collets.
Runs lovely!

That's a good early one. The pins through the valves are another early feature as is the 18mm spark plug.

My 4/2 has the serial number R6917SUVX and is of 1935 manufacture.

I thought your post was going to prompt lots of replies!
Yours must be one of the originals, any photos?
Don't hear much of the 4/2 I guess quite a few were made although being the oldest more have been scrapped. Really tried to find some history for mine but all I came up with was that it was under a guys bench for years and surfaced after he died when the engine was going for scrap. A local engine enthusiast heard about it and saved it but as he was up to capacity in the engine department advertised it for sale. I paid £45.
Do you know what yours was used for?

Alan

Not sure what mine did. When it came it was on a cast iron bed plate and had been directly coupled to some thing but not sure what. It was the first engine I bought I would be about 9 or 10 at the time. That was back in about 1979 it cost me £10.00. Will see if I can post some pics on here, but have never done it before.

Dale.