NOW SOLD
Off to Belgium
JAP OHV engine for sale 1937 500cc Twin Port with magneto & carb.
Prewar Single cylinder J A Prestwich Overhead Valve 500cc engine in good condition.
It might be possible to deliver the engine to parts of France, Belgium or Netherlands. Talk to me.
These OHV engines are useful for projects and installation in a variety of 1930’s sports motorcycles. Some of the marques that used an engine like this include: Cotton, OK Supreme, Montgomery, Lady, AJW, Universal, Radco, Eysink, Husqvarna, Imperia, New Imperial, possibly Terrot (I think they used 350cc versions), and many others.
This JAP OHV engine comes with a magneto and a Bowden carb. The Bowden carb was often supplied for Douglas motorcycles. However, I know that AJW motorcycles specified it too. You may not need the carb. It comes with it anyway.
The numbers on the engine show that this is an engine from 1937. The first three letters are KOZ. KO shows that it is an OHV 500cc engine. Z is for “dry sump”. The letter after the first oblique is F. That shows it’s from 1937. The last two letters after the sequential number are S & E. “S” suggests that it has a double roller big end bearing and “E” suggests that it was originally supplied with a cast iron, dished-top piston fitted to standard engine. Of course, that may not be the case now.
All I know is that it was rebuilt a while back with a new big end bearing.
The engine cases have matching numbers, indicating that the two halves are a pair from original build.
Condition of the JAP OHV engine
As stated, I understand that this JAP ohv engine has been rebuilt. It is being sold on the basis that you are buying an engine that will still need to be dis-assembled and checked over as it has stood for a while. It turns over very smoothly and it has good compression.
All of the fins look good and the engine cases appear to be without damage. There are plenty of images that you can zoom-in on. You are also welcome to come and check it over (externally) before purchase.
Other JAP ohv engine parts and engines.
Occasionally, I have some. If you don’t see what you need on the JAP engine page here, send me a note with your needs.
Sometimes, I put a notice up on TheTimingChest Facebook page letting everyone know that something interesting is about to become available. It may be worth following the page.
Buyer notes
Shipping is charged ON TOP of the price for the item. There are too many variables to include shipping in the checkout, so please contact me before you buy and I will give you a shipping price.

JAP OHV engine for sale 1937 500cc Twin Port with magneto & carb
I usually ship to most destinations.
International shipping available. Let me know where you are and I will send you a price for shipping with tracking
Combined shipping available.
Viewing: Please come and check it over before you buy. It is at PE28, near St Ives in Cambridgeshire.
Collection: If you don’t want it shipped, I have plenty of space. If you can’t collect for a while, it’s not a problem. However, I will need to be paid very soon after the sale. Thanks.
Payment: Good old fashioned money on collection is preferred. I can accept payment through PayPal or by bank transfer as well. I can accept EUROS. Please ask.
Import Taxes: Please note that IMPORT DUTIES are not something I can control. If you are buying from outside the UK, there is a chance that you will have to pay import taxes. Import taxes vary from country to country. If there are charges to pay, it is the buyer’s responsibility to research the cost and pay the duties. The price that you see on my advert is for the item and not the item plus whatever taxes might be due.