Databook

Would have preferred an older original version of The Book of the JAP but opted for a newer cheaper version.

And if one want, there is (not so good) scanned version that can be downloaded from the internet at https://motos-of-war.ru/wp-content/uploads/2016/05/The-Book-of-the-JAP-Engine.pdf

Albion BJ

Adjusted and simplified the scanned pages I found to only contain the BJ two-speed gearbox.

Notes.

- A5 Ball Bearing(s): 47x20x14 is equal to bearing number 6204 (originally SKF England)

- A35 & A36 Felt Washer & Retainer could be replaced by Honda oil seal xxxxx-xxx-xxx

- Use chain 415H

- Gearbox Ratios: 1st = 0,6 and 2nd =1

Cam Timing

According to the interweb

Model(s)	IN open	IN close	EX open	EX close	Ign.Adv.
	BTDC	ABDC	BBDC	ATDC	BTDC
175, 250, 350 sv	15°	50°	50°	20°	40°
500, 600 sv	16°	65°	65°	25°	40°
1100 sv	16°	65°	65°	25°	38°

Reference

 

Newsflash

Got me another JAP engine project too as well as the Howard GEM Rotavator ( rototiller) it is attached to. The engine is a 600cc s.v. Mark III Type 5

Engine number is:
UCZ/Z
94433\5

If I'm correct that would be:
U = 600cc Side Valve Engine, 85.7 x 104mm bore and stroke
C = Sports Engine
Z = Dry sump Lubrication
Z = 1933 Model Year

U is a standrd 6hp (4½ hp nominal) engine, according to The JAP book so what with the C marking?

The JAP Engine Reference there are more alternatives and the Mark III engine is recognized as a Sports engine.

My hopes were that I could get it started. By lubricating with the famous Omega Omicron  636 penetrating oil. So far I have got the valve lifter, throttle and most other leavers and functions to work.

Unfortunately the next step is to dismantle the cylinder head to see how bad the cylinder and piston is since the engine is stuck.

Parts List

The parts list is not easy to find but I finally found it, or so I thought.

Comparing the engine I have got to the sectional drawing in the parts list I found, shows that the are not exactly the same. From the parts number found on my cam follower (6170/F) compared to the ones in the parts list (6176 & 6177), one could believe my engine is older? But if the years given for the parts list, 1919-1926, are correct I doubt my engine is older than that.

J.A.Prestwich Industries

J.A.P might not need any further or deeper presentation, but anyway.

English engineering company and engine builder,  founded in 1895, defunct in 1965.

Made a wide range of SV and OHV engines, for motorcycles, stationary engines and cars. Both single cylinder av V-twin engines.

For me personally, I recognize the JAP brand mainly from their succes on the Speedway tracks.

N.U.T Motorcycles

There are a few sources on the internet about NUT Motorcycles, the name is derived from Newcastle Upon Tyne.

The short version is: From 1913 they competeds in motorcycle races and won the Junior TT at IOM. From 1914 they made motorcycles under the NUT name. Did not survive WW1, were declared bankrupt. Company (name) was bought and motorcycles were made from 1921 - 1933

Have not found much refernces to the NUT BTR (short for Board Track Racer from here on). Would like to hear from Trevor Hall and hear if he has any stories regarding the BTR's.

How it all started

For many years I've been drooling over pictures of old Board Track Racers as well as I allways wanted an old side valve engine to fondle with. Of cause there are a couple of them that I can pay a visit to at the local MC Collection whenever I want. That's just not the same.

The other week I was going through adds on the eBay and found this restoration project. An old JAP 250cc S V engine.

It was missing a lot of expensive parts as the Carb, the Magneto and the Oil Pump but I took a gamble that at least the internals would be possible to salvage and bought it more expensive than first planned, but what the heck.

When I later was scanning the internet for a parts list I stumbled over Trevor Hall's 600cc NUT Board Track Racer. From there on it was just to hang on and "go with the flow"

Rest of the few pictures of it can be found here.

The intention is NOT to build a replica of the above pictured racer. It is going to be my personal interpretation of a Board Track Racer, that will hopefully look a bit like the NUT