OutdoorKing Repair Forum Forums Collectors Corner Pictures of Antique Equipment Vintage Air Cooled Engines jap air cooled engine

This question could be answered by grumpy or any one else,i was visiting our local second hand shop and they have a small air cooled "jap"engine for sale.i have not asked the price yet because i want to do some home work.the engine is un-restored and not sure of its running condition but any thing can be repaired.
grumpy can you give me some info on these and what were they used for?...ken

J.A.P. (the brand name for John Alfred Prestwich's engine factory) was an English engine manufacturer that was very well known between the two World Wars, especially for the air-cooled V-twin engines they made for high performance motorcycles and the three-wheel Morgan car. After WW2 they were absorbed into Villiers. They made single cylinder engines as well as the V-twins, including some boring ones for Rotovators. You might want to start your research here:
http://en.wikipedia.org/wiki/JA_Prestwich_Industries

Some of their products were somewhat respected in high performance circles, but a lot of them were just air cooled stationary engines.

Thanks grumpy

Is there any technical information available on them, I have one on an old rotary hoe that I would like to restore.

Thanks

I don't know where you would get information other than in small scraps - probably you could make a start by looking for J.A.P. engine collectors or rotary hoe collectors on the internet.
http://www.donaldantiquerototillers.com/British.html

I haven't seen a stationery JAP engine in years. A rotary hoeing contractor dug up my yard with one of the 600 cc JAP-engined Rotovators in 1963 - that was the loudest, slowest, thumpingest "modern" engine I'd ever heard at the time.

There is quite a bit of information available on JAP motorcycles, and their post-WW2 racing engines, but I haven't seen anything on the stationery ones. You might start by finding the model identification plates for both your engine and rotary hoe, taking some pictures, and starting the process of emailing collectors.

cheers that was an informative read.

This J.A.P engine I have is a 2 stroke, it's currently not running. I think it's a spark issue as I had the plug sitting on the cylinder head and couldn't see any blue spark and then when I held it in my hand it only gave me a very little shock.

Looks to be a very simple engine, so I will pull it apart I think.

It's probably old enough to be a breaker-point system, so the process to fix an ignition fault is straightforward: check coil to flywheel gap, clean points, correct breaker gap and timing, check coil primary and secondary for open circuit, check wiring, and if it's none of those, try a different capacitor, then a different coil. Once you've found the fault, you can start the difficult part: finding a replacement part that looks like the original one.

If you need something like crankshaft seals or a new piston, you may be in trouble.

You might try sending a PM to Joe Brown, one of our moderators. Joe posted some very interesting information on J.A.P. engines in an early thread here (2002 - you can find it with a search), and has some personal experience with them. I have a few old documents on J.A.P. four-stroke engines, but nothing on two-strokes.