British Motorcycles

J.A.P. Motorcycles & Motorcycle Engines

J.A.Prestwich Logo

Brief History of the Marque: JAP

J.A.Prestwich was responsible for the design and manufacture of engines used in a great many famous marques and had numerous racing successes. JAP engines were still used in speedway bikes well into the 1960's. Complete motorcycles were built from 1904 to 1908, and subsequently the factory concentrated on supplying its proprietory engines to other manufacturers. After 1945, production was taken over by the Villiers factory.

The extensive list of manufacturers which used JAP engines includes:

Alldays & Onions
La Mondiale
Le Grimpeur
New Hudson
New Imperial
New Map
Royal Enfield
Royal Ruby
San Sou Pap

JAP engines were also used in a wide range of industrial and other non-motorcycling applications including lawnmowers, railcars and early Reliant 3-wheelers. Farm machinery included the Clifford rotary hoe.

Wed Oct 28 2015
stewm 0001 at
engine identification aplication
j.a.p single cylinder
hi stewart marshall here to try find out what my j.a.p engine is and what year if poss the only numbers on the engine is a/c 16603 and on the primery chain drive for the mag is birnal 6678 i hope you can help me find out what this is and what it was used in yours hopfuly stewart

Thu Nov 12 2015
loyolamccarthy at
Jap 500 long stroke
Hagen frame Jap
Can I get engine parts for jap 500 I need gear box & clutch unit 3speed albeum (Albion? Ed.)
Southern ireland cork

Sat May 09 2015
clive.girdler at
Jap 600 not returning oil to tank on gem
jap 600 side vlave
hi I have a Howard rotavator gem my 3 fitted with a JAP 600. There is not oil returning to oil tank but the motor seems to be running ok when I fired up for the first time. Any advice.?
kings Lynn UK

Thu Jan 08 2015
jh at
use of engine
jap howard gem
Hi I have gone an old howard gem with a jap 600cc side valve engine fitted the body is shot but the engine is good turning over with compression i used to use it in the mid 80s can the engine be used to form the basis of a motorbike thank you john hacker

Sat Aug 02 2014
timothypiller at
46 Roccio
JAP horizonatal
I am trying to aquire my grandfathers (Ernie Roccio) custom built JAP bike and wondering what to value the insurance on it, due to its innovative design and racing history, any help would be appreciated.
Patterson, CA USA

Tue May 27 2014
dc7073 at
engine parts
J.A.P single cylinder 2A/ T M6
i am after rings, shells and gasket, for this vintage engine, where do i start thanks dave

Mon Feb 17 2014
sergevidal.33 at
renseignements moteur JAP
JAP Moteur HB de course
Merci de m`aider à dater et identifier ce moteur. A t`il était assemblé par l`usine JAP?
Je n`ai encore rien trouvé sur ce modèle......

JAP-1960s-Outboard-FR-1.jpg will be posted-1402

Wed Jan 29 2014 frappi AT
ZEV Magnetoon the JAP engines Jap Jap

I am interested to know what years of JAP engines used the ZEV Bosch Magneto. Any info that you have thats easy to access that gives reference to the ZEV Magneto as used on Jap engines. Thank You, Mark Ohio USA

More information perhaps under Electrics

Thu Jan 16 2014 po2004 AT Motor Jap w tvin770 w tvin770 I am writing to you from Ukraine, I have to buy the motor from Motorcycles JAP................. Intirisuet you????tel+380974249600 Ukraine

JAP-770cc-V-Twin-Ukraine-1.jpg will be posted-1401

Thu Dec 19 2013
JAP stickers
JAP Speedway Bike

We have just finished doing up my 1970 4b speedway bike that I rode in GB and NZ. I am trying to get hold of some JAP stickers. Approximately 50ml high in black. Do you know where I could find JAP merchandise like this?

Any help would be greatly appreciated!


Nick & Ian Ross

Try this page for logo resources.

Thu Oct 10 2013
JAP CUSTOM have look to a custom j.a.p from greece!its built by a collector who couldnt find some parts

Different. Anyone know what that front end is, or what "JG" refers to? Ed.

Wed Sep 18 2013
Identifying engine
JAP possibly 4B
I have just bought a JAP Speedway bike with unidentified frame and engine. The only numbers I have found on the engine do not correspond with what I have read about the ID system used. Please can anyone help? There is an Amal 932 carb. The bottom of the block shows 11238-1 with H, then a larger 'S', followed by a standard size 'O', and beneath tta is stamped the letter R. On the forward facing fins at the frobt of the crankcase is stamped 12298SA. Thanks.

JAP-Speedway-Exeter-1.jpg will be posted-1309

Fri Jun 14 2013
Jock McNeil
1913 J.A.P. unknown
Jock was killed practicing at the Motordrome in Atlanta in August of 1913 with a bike it was said he brought from Scotland. Is there any old research from Scotland or a source for old stories from 1912?
Decatur, GA,USA

Wed Feb 20 2013
Fairchild-Roccio JAP
JAP Ariel- JAP
I noticed that this archive is the only webisite online that has pictures of the original Fairchild JAP that was created for Ernie Roccio to race. I am Jonny Roccio's (Ernies brother) grandson. My father, Ernie Roccio currently owns this bike, along with a 46' ariel that was raced by my grandfather. I have uploaded pictues of both bikes, and would be grateful for any information you might provide on them and on my families racing careers.

Washington, DC

(images emailed were thumbnails only)

Wed Jul 25 2012
J.A.P. engine parts
Hello from Finland
I am restoring a motorcycle with JAP engine.Engine number is 927988.The engine is missing a few parts: valve guides, push rod, oil pump is broken, the magneto gear wheel to the engine, exhaust pipe fixing nut, spare parts catalog would be a good.
If anyone would have these parts I could get my projects forward.

Tue Aug 14 2012
JAP Flatracker (Shit getter)
Photo to update Chris Bayles web site

Mon Jan 07 2013
1947 5 stud jap
jap 500cc 5 stud
This is Jim Apple, I still have the 47 JAP and it is still on my wall.
I noticed that you referenced that you had no photos on your web site.
I hope that this will fill the void for you


Mon Sep 17 2012
hartawans<at>yahoodot com
need help to identify this engine
JAP 1915
I have this engine few weeks ago. does anyone here know about this engine? It said it was JAP engine...but i never can found any information what JAP bike that had been use this engine...
I will appreciated any info/sources that I can use to seek the details about this engine

Jakarta, Indonesia


Thu May 10 2012
I'm looking for a cylinder with its piston for a 350 OHV SOC or SOR

Thu May 10 2012
JAP Engine
36212 500cc OHV
Dear Sir,

I have an engine: 500CC OHV with one inlet and one outlet vale and one exhaust pipe. The number of the engine is 36212.

Do you have an idea from which year the engine is?

Sun May 13 2012
boa48<at>hotmaildot com
Jap engine
Jap 1915
i have a engine that i believe is a Jap 1915 770cc engine.What bike could it come from? What kind of magneto, carburretor and gearbox was used on this engine? Anyone who knows where i can find the parts or a rolling chassi?
Kind regards/


Mon Jan 23 2012
JAP Water Cooled V Twin
I am looking for details of a JAP engine which was manufactured in 1939 and is a V Twin but water cooled can you assist

Sat Jan 21 2012
speedway jap 4b engine no
jap 4b rotrax speedway bike
can you tell me the year of my jap speedway4b? no is
JOS/W 75684/4C. thank you
east anglia uk

Fri Jan 13 2012
jap solo
any any
looking to buy a jap solo.could you please help out?

Thu Feb 16 2012
JAP crank???? HELP!!
JAP? big twin
88b on rods


Thu Dec 15 2011
fairchild horizontal
jap speedway bike
Hi everyone. My name is Ernie roccio and i have what was told me by Jerry Fairchild is the original and only horizontal he built for my uncle Ernie Roccio to race at Lincoln Park where he won the speedway national championship back in 1949. Ernie also used this bike to qualify for the 1952 world championship before he died racing in england. prior to the finals. My dad John Roccio loved this bike and Jerry made it all possiable. I grew-up with the speedway crowd since the 60's and feel fortunate that the lifelong friendship my family has had with the speedway racing circle very special..Briggo where are you?

Fri Oct 21 2011
j.a.p engine no
hi have found an old bike under a house can anyone tell me what this engine no means 8/68630\EXIL

Tue Oct 18 2011
Bédélia DB 12
I do not have a manual for my 1914 JAP engine what type of magneto was used on the twin model? Looking for a photocopy of the JAP engine manual will also be appreciated.
West Texas

Wed Oct 12 2011
JAP 750 cc engine
Many people are interested in the small JAP 750 Vtwin which is relatively common as it was fitted to the Lister Autotruck.A suitable piston for reco is the Villiers MK25 stationary engine,near identical,pin is 8thou different.Incidentally there is a Zenith on Aus ebay right now,maybe same frame as this forum,maybe using MT bottom end.Seller is a very active ebayer .Regards.

Sun Sep 25 2011
carburettor needed
JAP engine 150cc C1920
engine still in use on my dad's lawnmower but carb has been fixed too many times can anyone help us find a replacement have been told a Zenith 13DT/2 would have been original but can't track one down.Help anyone? (dad's 83 and still mowing strong! he was born in Tottenham just round corner from JAP and getting engine fixed is on his bucket list, one day i'd like to put it back on two wheels as nature intended!)
Thanks in anticipation
Jill, Scottish Highlands
Perthshire UK

Wed Nov 16 2011
nickbert-81<at>hotmaildot com
?? ??
Hi Everyone,
My name is Nick Bertram and I am the grandson of Herbert "Nicky" Bertram who was involved in the Camden Motordrome track in Adelaide in the 1930's.
I have some of his old pictures and a JAP signed letter regarding Engine Specs, I would like to know if the bike or engine in the photo is a JAP & what model is it?? Thankyou
Perth, Australia

JAP Speedway Bike 1930s

Tue Aug 16 2011
JAP v-twin 770 ccm 1916
cylinder Royal Enfield 180
The front cylinder has cracked the top. Is there anyone who has a cylinder to sell me.

Sun Jun 19 2011
Excelsior 250cc J.A.P. engine
I am searching Bayliss-Thoms 250 cc /J.A.P. engine 1936

Sat May 21 2011
jaclassicpool<at>gmaildot com
V-twin JAP engine
replica JAP
do you have Jap V-twin engine replica for sale,
please let me know, because i really need a engine.
Anything please let me know!
Sri lanka

Fri Feb 25 2011
JAP engine spare parts
JAP 350 year 1933
please help me! I'm in Italy, here is hard to find what I'm looking for. thank you very much in advace for your help!!!

could you please help me to find crankshaft with rod (lenght 172 mm) for
JAP engine 350 year 1933 10zz N°31751? I give you some other information: on the rod there is written: JAP 7102 6 3/4 -the engine has a gear box 4 speeds Burman CUCA I 280 - the engine is on an italian bike GANNA.
thank you very much!!!

Wed Feb 23 2011

jap 350 year 1933
hello, could you please help me to find crankshaft with rod (lenght 172 mm) for
JAP engine 350 year 1933 10zz N°31751? thank you very much!

Sun Feb 20 2011
rrmini<at>hotmaildot com
Fairchild JAP bike
JAP Laydown JAP
Hi I am Jerry Fairchild granddaughter. I can say my granddad was a great builder & great at networking in his days. To all of you who knew him I thank. He has been gone since just before Christmas 1989. His son Geralg-BUTCH is still here alive & kicking. I think of the fun my brother & I had at the races..It is great to see Jerry's name on the net-He would never had believed it.. best wishes to all the Racers out there.. in mind & spirit.. Robin Fairchild Stewart.
Lancaster, Ca

Fairchild JAP

Thu Feb 03 2011
JAP engine
Hi, I have been told that this is a 1915 JAP engine, I would love any information as to what bike this may have come from - for example what gearbox & carburetor would have been used with it - any other applicable information would be of great interest!

The numbers stamped on the engine are S1C & 4813D.

Thank you, Alan.


Tue Jan 18 2011
gtsubarugt<at>hotmaildot com
carb parts
howard hoe gem II
im after a carb or a rebuild kit my butterfly is half rusted away and so is the needle valve can these bits be replaced
new zealand

Howard-Hoe-Gem-II-NZ.jpg posted 1101

Mon Jan 17 2011
comficampers<at>wwwiresdot com
Engine # MTS/N888615
J.A.P. 750cc Short Stroke
Can anyone help me with info on this motor, is it 4 or 2 stroke,the approx years it was manufactured and was it made for a motorcycle or stationary implements etc?
NSW Australia

Sat Nov 13 2010
johnlamb224<at>btinternetdot com
engine number
jap por/r
could anybody please advice me what jap engine number por/r 40251 was fitted to,or where I may find the information thanks

Wed Nov 10 2010
cylinder head, rockers, valve pushrods
JAP 4B, 500 ccm
cylinder head with valves, rockers, pushrods urgently needed

JAP 4B 500cc Speedway Bike Zagreb

Sat Oct 09 2010
rabaraz at
Jap twin water cooled 750 cc engine
Jap engine number MTWD\V 62105\S
This engine was installed into:
Aveling Barford 3 wheel or
Reliant 10cwt 3wheels.
Is anyone able to provide any design about it?
Milan Italy

Sun Sep 05 2010
didjawh3 AT
JAP Motorbikes
approx 1924 v twin
I have a motorbike which i was told was a Raliegh it has a vee twin JAP motor but i can not fine any engine number that matches i think its a JAP motorbike
Eng.# 8/68640 EXTD
Frame 35008T
Gear box CRS NA
if you can help me thanks very much Allen Potter if any one knows what it is please let me know Thank you

It the engine is a JAP then it's probably not a Raleigh as it appears they did not use JAP engines.
thank you ...when i find out what this is i will let you know. It is very well designed with one bar on the forks are oval shaped and the headlight has a very a difference designed to secure the head light it the marking and enging number thats strange...
JAP stick out from the casting but the word Ottenham words confussing any way i'll find it i hope again Thank you Allen Potter
Perth Western Australia PS my friend and myself bought dozens difference bike and frames and wheel that have been in barn all over Australia

Thu Aug 05 2010
price help
JAP Speedway
my uncle is looking to sell his circa 1950 jap speedway bikecomplete and running (runs on methonol) but does not know how much it is worth can enyone help with a costing.
Cheers alan

JAP Speedway Bike circa 1950

Wed Jul 14 2010
aldofantini<at>hotmaildot com
JAP 350 1929
Hi, I have this JAP 350 1929 engine and I want to know the motorcycles it belongs. Thank´s

JAP 1929 350cc

Thu Feb 11 2010
ihtech at
Jap 500 cc sandbahn engine
500cc Jap Speedway bike
I have cams and designs for this engine. The race cams were designed by Rudolf Hofmann he used this design to win euro master championship in in the early 70s email me back I have cam and rod designs. I also have the cams also.


Mon Dec 07 2009
lydie-deceuninck at hotmaildot com
JAP gastank
JAP Verry old
I have a verry old JAP gastank 68cm long 13 large 11 high
Have somebody one idea ?

JAP circa 1910-1919 tank

Tue Dec 01 2009
wste at
Clifford Magneto
Clifford MK4
Hi there,
I was wondering whether any of you and /or your members would know where I might pick up a magento for J.A.P. 600 single cylinder engine>?
I looked up the manual for the engine and it states that this engine requires a:
Magneto, Wico, type A1041 B.Z.
Magneto rotation Anti-clockwise.

This engine is in a Clifford MK4, Rotary hoe build around 1956.

If there is no second hand magneto possible to source, would there be an equivalent? And if so where coudl I turn to enquire about that mag then?

Thanks a lot in advance for all your help.


Possibly some information on Wico Magnetos under Electrics

Tue Nov 24 2009
dwiese at
jap 2 cyl
one of my Listers, a lister auto truck, has a jap engine
westlock, alberta, canada

Tue Nov 24 2009
tom.veevers at hotmaildot com
jap 600 sv
can anyone tell me anything about.
ucz/r1108/8d and is it worth much to sell on. thanks , tom

Sun Nov 01 2009
charlesheyden at gmaildot com
Copyright to image: "JAP 500 Speedway 1949" image?
Japaneese 500
I am the author of a book of poetry, Poetry My Mother Would've Approved, to be published in the U.S. The photo of the JAP 500 motorcycle that I found through Google Images and on website is of interest to me for illustration purposes in a poem in that anthology. Do you own or know the person who has the copyright?

My publisher requires release of rights, solely for this book.
If you are the copyright owner, will you consent to and sign a release letting Publish America do this?

C. Van Heyden
PS. Attached is the image sought.
United States

Bert Knoester is the copyright owner. Ed.

Sun Sep 06 2009
DadnDavesengines at gmaildot com
JAP D270
Hi, Do you have any images that show the other side of this engine? We have just bought an old engine and want to see if this is the same, many thanks Barry
Qld, Australia

Sun Aug 30 2009
spekebay at
J.A.P. books
I am looking for the below two books, but re-prints would be fine also:

1. The JAP Story 1895 - 1951 from D.J. Buchanan (Publischers: J.A. Prestwich and Co. Ltd

2. The Story of the Racing JAP from Cyril May (Published by Cyril May)

Thanks in advance.


Jan W. Halfwerk
Tanzania, East-Africa

Sun Aug 02 2009
geoff.gradden at sigraildot com
JAP engine info
I have a JAP 84C 540cc speedway engine that's just bent a valve from colletts falling out. I would like to know where I can get an exhaust valve, collets and retainer. Also if anybody knows about conrods in this model. Its definitely non magnetic and highly polished and I assume its aluminium. As the 84C was a late model, are these prone to break and should I replace it with a steel rod? If so where would one be available?


Geoff Gradden
Sydney Australia.

Thu Jul 09 2009
AliaZ3Gun at Gmaildot com
JAP engine SV.600cc
I have an JAP LONDEN engine side valve 600cc with this serial number: UC/C is above this number 86405 s.i want to know,information about this engine and what's price this engine?thanks lot


JAP 600cc SV UCC

Fri Jun 26 2009
jura051 at
jap 175ccm
podaci o ovom modelu

JAP 175cc

Wed Jun 24 2009
Chater Lea 1910
...c1910 Chater Lea / JAP with 1905 pattern Auto Inlet Valve engine....I claim this to be the oldest V twin JAP in going you know of an earlier one?

More information under Chater-Lea

Mon Jun 15 2009
ramavneri at
JAP 1911
Ineed parts: geer box and magneto and manual book for JAP v twin 1000cc 1911.

Thank u

Sun May 31 2009
dgrinsh at hotmaildot com
JAP motorcycle 1911
JAP 1000 cc
need gearbox for JAP 1000 cc motorcycle and any other parts available. All info and parts welcome on this bike
Cincinnati, USA

April 2009
Hi my name is shane edwards & i live in sydney australia
I noticed on your web site that you have a JAP vtwin derbyshire side valve is this a 750cc
Would you be able to advise me where i could locate a work manuel for this

Thanks Shane
----- <rpedwards54<AT>>

Possibly something under Books and Manuals

Mon Apr 20 2009
cd.cross at btinternetdot com
Sent two pages from J.A.P Engined Motor-Cycles published around 1950, and several images of a JAP SV circa 1928.

JAP circa 1928 Sidevalve

JAP Engined Motor Cycles

Mon Apr 06 2009
markbaker at
J.A.P. Engines
Large capacity single cylinder or any V-twin n/a
Conacts of people/organizations I might approach in order to make a purchase? I have been trying for several years now with no success. Many thanks,Mark.

Wed Mar 18 2009
leobortolotti at
JAP engine
I have this engine, can any one tell me about and what bike it was?
many thanks

JAP F2UH Twostroke

Fri Jan 23 2009
tubehead at
JAP road Race special
JAP Road Racer
I have a complete road racer special with JAP cross flow head I am considering selling, if you or you know of someone who may be interested please contact me.

I have owned the bike for the last 8 years but have never used it, I have a small private museum specialising in unique vehicles.

It has a 1930-31 BSA frame with a "Uniweld" rear spring conversion.

Kind Regards

Geoff Edwards

New Zealand

JAP BSA Uniweld

Tue Jan 20 2009
bullet101 at bigponddot com
jap 770cc
royal enfield 180 ?
Could you please date the following jap v twin engines i have .? 1 is fitted to a royal enfield and the other came as a spare . first is 36781 and the second is 40443. there are no letters on either motor pertaining to engine number
Hi Mate
Have included pictures of the two motors . I have found a very knowledgable and helpful person who thinks the bike or at least the motor may be 1912 or 1913

JAP 1912-1913 V-Twin

Sat Dec 20 2008
pethans14 at gmaildot com
Howard rototiller V twin 1300cc engine
Howard 8
Any message about the V twin Howard 1300cc, from Denmark, now Wisconsin, is requested sent to [email above] thank you very much. I need a cam and the gear on the crank for this motor, presumably a Howard of Australian origin.
Cornell, Wi

JAP Howard 1300cc

Thu Nov 20 2008
tuta48 at
I Need help to identify JAP
Hello! I am from Slovakia, and I have motorcycle JAP.
I need a information about an JAP motorcycle engine from the year 1921 - ??,OHV, 1 cylinder - single - , 4 valve,2 blow-out. On the engine is scripture KN 06, on the basin is scripture JAP . I'd like to know, if you could tell me more about it.I send photo.
I also speake German! Or slovakei
Thank you very much!

Juliana Ptacek

JAP Motorcycle circa 1921 KN06

Thank for answert, I dont know, whot is on the engine : NK O6. It is not write JAP. Title JAP is only on the basin.


Wed Nov 19 2008
shoscombevale at
Jap London crankcase
Jap London
I have a Jap London crankcase with the letters YOS D marked on it, these don't seem to correlate with the letters on your site. Would you be able to tell me cc and year of manufacture from these letters please?
Thanks in advance for your help,
Bath, UK

London is not the model, it's where it was made. Ed.


Mon Oct 13 2008
iron-ariel at
JAP manuals
Finally found a source for JAP manuals-

Vancouver, Canada

See also Books and Manuals

Thu Sep 18 2008
jekkal at
JAP engine 350 cmm sidevalve
I am looking for a oilpump to my motorbike.
It is a French bike with a JAP engine. Year 1927 model I, maybee a whole engine.

Mon Sep 15 2008
jarmo.mursula at
Wantted JAP 500 or 350 OHV engine
JAP 1920 - 1930
I am looking ohv Jap engine from 20's or 30's any condition.

Jarmo Mursula

Sat Aug 30 2008
terencecarrington at
stationary engine
Jap N7  ??
Hi,i have a stationary Jap engine on a rotavator, could you advise me where to locate Wico ignition parts from.the engine No is 19266F.
Regard's Terry.

Possibly some information under Electrics

Tue Aug 26 2008
daiedegas at yahoodot com
Jap conrod
Jap 500cc
I am after a conrod for a motorbike Jap engine 500cc.
Unfortunately I don't have the engine or part number; but I can enclose a detailed sketch with measurement in “mm” millimetre. If an exact match is not available I can use a similar conrod as long as the length is identical or even slightly longer (but not shorter). I can adapt with minor alteration the diameter sizes of the top end or the bottom end.
Thank you for your time
L. Zanchi

JAP Conrod drawing

Wed Feb 27 2008
comeon7s at gmaildot com
JAP Engine parts available !!
jap all models
Here is a web site for J.A.P parts and complete engines ...for bikes,morgans,airplane
great white north

Wed Feb 06 2008
micheal.atkinson at btopenworlddot com
jap engine
jap sv v twin
hi i have a jap sv v twin engine 750?.i can not find any numbers stamped on the cases.there is a number on the brass arm on the lift at the top of the crank case on it is 3130511. thanks for in identifying the engine, model ect,,
derbyshire uk


Fri Dec 28 2007
lencam at bigponddot com
JAP Spark Plugs

I am looking for new replacement spark plugs to suit a 1947 JAP 5 Stud Solo 500cc engine.
Are there any new equivalents for the old Lodge R49 methanol plugs? They must have 3/4" reach with internal electrode & heat range to suit methanol.
Brisbane Australia

There may be some information on our fledgling page about Classic Motorcycle Electrics.

Sat Oct 20 2007
neatheryt at
JAP in the movies
In the movie :"Lawrence of Arabia" the actor is shown mounting a cycle on his last ride. The letters on the engine are JAP, but what is the bike?

I don't know which bike was actually used in the movie, but TEL died following an accident on his Brough Superior. Ed.

Wed Oct 17 2007
stubbs785 at btinternetdot com
information about J A P engine
JAP v twin side valve engine number 32198
has any one any information about this engine? please

Thu Sep 20 2007
ramavneri at
a rare v engine jap
1911 to 1914?
i have an old frame and v engine (1000 cc.) of a jap motorcycle.(1911-1914?)
i need a matching gearbox and the part that gives the spark to the plug.
i need all kind of info of the engine and the other parts.
thanks in advance,

21st Sept 2007
subject: Sheldon EMU
Email: toddjayporter at aoldot com
message: Hello,

I have been scouring the interenet for information regarding a bike that I am helping a friend sell. He owns several vintage motorcycles, however this one in particular has been a bit difficult to seek information on ie: value etc...

This bike, JA Prestwich Speedway is owned by my friend who acquired it in the early 1950's from a raceway in NJ.

The bike is in it's original condition and has several extremely rare characteristics that I think would be of interest to a prospective owner.

Before I waste time going any further, I would like to ask if you have any knowledge of websites and or locations that would have interest in this rare bike.

I would appreciate your reply either way and in advance thank you for your assistance.

Unfortunately I have tried to forward this message to Sheldon EMU and the server has timed out. This is where it guided me to.

Todd Porter


Tue Sep 18 2007
spyker at
Jap school project
JAP IY/I 1927
I need a information about an jap motorcycle engine from the year 1927. The motor code is IY/Y. We have to restore these engine for a school project. I now that the first I stands for 350ccm (70x90). The second I stands for the year 1927. But for what is the Y. I read that it stands for twoport exhaust. But my engine just has one exhaust.
I also speake German!
Thank you very much!

Thu Sep 13 2007
kflc at bigponddot com
Crank pin tightening torques required.
JAP 600cc mark 3 type 5
Hi there, can anyone supply a torque value so I can correctly tightn the crank pin nuts after centering the crank flywheels.

Fri Jul 27 2007
wilkglenn at hotmaildot com
Jap engines morgan cars

Was an early morgan car ever produced with a Jap engine?

Yes, Morgan JAP's were built during the 1930's. Ed.

Sat Jul 14 2007
swords at bigponddot com
JAP motor
F/E28549D 1922 300cc
Have above motor fitted to 20's Triumph frame. Need forward facing magneto chain case, inner/outer.

Tue Jul 03 2007
jabberncc at aoldot com
jap engine?
i have a jap engine it is small and has a 3 speed box the engine n0 is 2v/h 82187/3 can any one tell me what bike it was in and any other info please. it could be for sale. thanks. NIGEL

The engine number appears to be 2U/H. Ed.

JAP 2UH 2.jpg

Fri Apr 20 2007
biffhez at
Hi ,Ive come across a JAP engine ,its a side valve,with an integral head and barrel.I'm guessing its between 200 and 250 cc.Its has a mag platform to the ear ,and JAP on the timing cover.Also has JAP London on drive side .Is it from a motor cycle and if so what or a stationary unit.Regards Chris

JAP sidevalve Fife.jpg
JAP sidevalve Fife

Tue Feb 27 2007
debandstu at gmaildot com
1950 Howard Rotovator w/ JAP motor
I have this rototiller and I'm wondering if someone collects, restores or salvages parts from them. I also have the original manual that came with it. I'm in the Seattle, WA, USA area and wonder what you might tell me.
Seattle, WA, USA

SOLD Dec 07


Wed Feb 21 2007
hornetvip at
Piston+rings for JAP 600cc industrial engine
JAP 600cc
Need help to locate source for piston assembly +rings for above engine

I'm fairly sure there's someone who does such things listed in the Engine Parts directory:

Mon Feb 19 2007
pearsonriley at
JAP Engines
1937 engines
i have two engines at home, koz/f [serial]/s and koc/f[serial]/sm

the KOC engine has finning on the timing side of the case, where as the KOZ engine doesn't (if has this funny protusion that runs diagonally from the timing side.

how do i tell what i've got? also - will a J head fit (smaller bore); i need one for the KOC engine, as its going to be raced this year.

final bit - does the pilgrim pump indicate age of the engine? or where they used indiscriminately?



Fri Jan 26 2007
Jiwillia at msndot com
Speedway 4A/4B 500cc
I have cam for the JAP 4A/4B speedway engine with X stamped on it. Does anyone know what this signifies?
Devon, UK

Jan 9th 2007
As you can tell I am an Indian guy all the way (10 or 12 of them)
I need a set of OHV heads to fit to some Crocker jugs I got. Whole lower end
is Indian. I am told JAP, Matchless will work. Just what I need a new
[See forums. Ed.]

Tue Jan 02 2007
g-skilton at hotmaildot com
parts needed.
jap mk 2
does anyone know where I can find acylinder head for a J.A.P mk 2 motor these are the aluminium ones, also need a rocker box. thanks Geoff.

Thu Dec 07 2006
brufsup at aoldot com
I am assembling two JTOR engines and need new pistons. They have 80mm bores. Can anyone help please. Also one needs cam followers.

Wed Nov 29 2006
dupuis-marc at
jap couvercle
je recherche un couvercle côté entrainement pompe à huile et magnéto pour moteur jap 350 culbuté an 30

Robotrans: I seek a lid (cover?) side drive pump oil and magneto for JAP 350 engine collapsed year 1930
(it's a timing cover he's after) rebonjour, ci-joint les photos de la moto que je possède dont je cherche le couvercle entrainement pompe àhuile et magnéto.

salutations de la corse marc.
la marque est soit une soyer soit une radior pour le modèle je cherche encore!!

à bientôt marc.

JAP 350 France 3.jpg
JAP 350 France 3

Sat Nov 04 2006
renegade.geordie.john at
wickham trolley engine
I am looking for a book on the magneto fitted to the Wickham trolley v engine in the 1930's, can you help me please ?
Suffolk, England
Hi, it is a Lucas mag, fitted to a J A P twin.

Peter Scott Motorcycles may be able to help - they specialise in magneto repairs:

Alternatively, try the section at Bikelinks on magnetos

Sat Oct 21 2006
luukrabbers at
J.A.P Diesel D270
Have jou any information of thees JAP?

JAP Diesel D270.jpg
JAP Diesel D270

Tue Oct 10 2006
pethans1 at hotmaildot com
Identifying Jap engine
I have recently purchases an engine at a swapmeet here in Denmark, I would imagine its a JAP, but no numbers or letters are found on it, the motor is all steel, bore is 88,3 mm stroke is 115 mm. Magneto and carburetter is british, KDV 50A4 and Amal. If anybody can tell me what it is I will appreciate this very much.Thank you

JAP Vtwin Denmark.jpg
JAP Vtwin Denmark

Fri Jul 06 2007
pethans1 at hotmaildot com
JAP Engine Denmark
Sidevalve large displacement
The question asked about the enormous sidevalve engine found in Denmark, can not be answered to the current address( email) please write to pethans1 at hotmaildot com with information about this engine.
Thank you very much. Peter Hansen
Wisconsin USA

Sat Oct 14 2006
bslark at
outboard motor
J.A.P. See-Bee [?]
Any information on this motor? we want to display it in the museum with JAP powered motorcycles
b/ham alabama USA

There is information on JAP outboard motors here:

Wed Sep 20 2006
JAP aero engines
Because of my interest in Martinsyde aeroplanes I am looking for information concerning JAP aero engines... read on

Thu Sep 07 2006
ken.judec at gmaildot com
new v twin JAP motor
I have heard that someone is making new JAP engines now. Is this correct??

Fri Sep 01 2006
rbbmarkey at
JAP single

I have a JAP single and from the info provided in the codeing link I know it is a 600 side valve sports 1933 UCZ/W but can anyone tell me what the W stands for. Also what gear boxes can be used with this engin any info greatly accepted

JAP 600SV 1933.jpg
JAP 600SV 1933

Sun Aug 27 2006
hornetvip at
JAP old industrial generator drive eng.
Need help to identify JAP industrial engine,single cyl. 86 mm bore (now)with follw.markings on crankcase:6T59587G
Can you pls help??

Fri Aug 18 2006
chimpilin at
Moto JAP
Motocicleta JAP 1949
Adquiri en una desarmaduria una JAP 1949 500 cc obtener el manual u otro atecedentes a fin de restaurarla
Chile, Curicó

Robotrans: Adquiri in one desarmaduria a JAP 1949 500 cc to obtain manual or the other atecedentes in order to recover it

Wed Jul 26 2006
happyhamrax at yahoodot com
350 RACING 1927
have a collection of parts trying to put together need some info and a source of parts
main bearings are they ball journals or loose rollers and cage as other jap have worked on
also dont have timing covers ,does anyone know if should have oil pump as flywheels i have are oil fed any help please thanks shaun
I only have the engine have enclosed some pic,s the inner timing cover dos,nt match the outer,I prezume inner correct and racing/speedway etc as rear mounted magneto if anybody could let me know if rollers and cage mains(as some jap.s have worked on) or ball journals ,also if pushrods should be enclosed or open as you can see by photos looks like tubes have been cut but as racing may have been like this std ? Havn't the foggiest this early /model any help /spares would be appreciated shaun

Jap 1927 350 Engine.jpg
Jap 1927 350 Engine

Fri Jul 21 2006
solano at btconnectdot com
60 degree jap engines

were there any and what were they used for

Thu Jul 13 2006
rushman69 at hotmaildot com
Lost JAP powered speedway bike
Unknown frame with JAP 500 Engine
Hi. This is a wild shot in the dark. My father used to race speedway in the late 50's and early 60's before going going into pub management. In the mid to late 70's he was manager of The White Hart Inn, Devonshire Hill lane, Tottenham, London N17. When he moved from the pub in around 1975 (ish) he left his JAP powered speedway bike in the cellar of the pub to be collected at a later date. He never did collect it and when I chased it up a few years later the present owner said they had had a clear out and took the old bike down to the local dump. Now I am hoping against hope that someone rescued the bike and that someone out there someplace might know the current whereabouts of this machine. If not to sell then to send me pictures and get some more history of this bike and some old pictures of it in its prime from me. Maybe someone knows something or heard a story about such a bike being found in a scrap yard. Anyone with the slightest inofmation please contact me at rushman69 at hotmaildot com. Many thanks.
London/New York

Mon Jun 26 2006
CLLMCL at AOLdot com
I have an old jap speedway bike I have been racing, how can you tell what year it was made in?

Mon Jun 19 2006
moragfraser at hotmaildot com
JAP engine
I have a jap engine no F/E 26328/D
I wonder if you could tell me more about it.
Many thanks
Mike Clifford.
Aberdeenshire, Scotland.

I think it's a 375cc sidevalve 1922 model with a cast-iron flat-topped piston. Ed. Thanks for that. Do you have any idea of the value of this engine? I have never had it running but its not seized, It has carb, Gearbox, chains , gear change , kick start, although it needs a clean up and perhaps the kick and that sort of thing would need chroming or what ever finish it needs. Any ideas? Thanks Mike.

Try the page on Motorcycle Valuations. Ed.

Mon May 29 2006
neelix1961 at
J.A.P staionary engine
?? 100cc i think
Hi anyone got a gasket set for a amal carb
no 379/9 for my jap engine any one help

Thu Apr 06 2006
martyn.hague at
Jap engine
Racing V twin or 1960's speedway
I am trying to purchase either of the above to restore, and would love to know if anyone has an engine for sale or knows where to look.

Mon Mar 27 2006
davidmorys at
JAP Single cylinder
Serial number IY.WMS 86239
I am trying to identify this engine a 350cc side valve (from the letters) but its not got twin exhausts. Year I presume is either 1930 or 1950.
Is it a motorcycle engine it looks similar to any other JAP in layout but there are no JAP identifying marks, name or otherwise apart from serial number.
Your help would be appreciated.

Thu Feb 23 2006
rosbaldiston at
jap speedway motor
i am in the process of pulling a jap speedway motor down...i've taken the oil pump and cover off... do i need to pull the magneto sproket and chain off to get the timing case off....ggreatly appreciate any help.... russell
brisbane australia

The JAP directory at Bikelinks would be a good place to search for more information
I'm sure that I've seen a site in Bikelinks which has JAP manuals to download but it's not listed in the JAP directory.

Tue Feb 07 2006
concretesu at aoldot com
J.A.P. engine
Looking for info on J.A.P. engine F/U 9861.Such as cc. Year, use on type of motorcycle , equipment.Thanks Toni
United States

The engine appears to be a 300cc SV 1923, and may not have been used on a motorcycle.

Mon Feb 06 2006
t.eronen at gmaildot com
J.A.P racing engine
Hi. I have one interested JAP engine. It is 600 cc ohv racing engine, year is 1930. It is twin port head and very larges both valves, engine number is UOR/W,....I cant remember those numbers.
Do you have any ideas, how is using this engine?

There is a page on JAP engine numbers here, but this one is not listed.
Another similar page of JAP engine serial numbers.

JAP 600cc OHV Engine UOR-W.jpg
JAP 600cc OHV Engine UOR-W

Mon Jan 23 2006
renegade.geordie.john at
Hi I am after some gen on the Jap 600 side valve engine as I am about to rebuild on, can you help me ?

Mon Dec 26 2005
demarscomics2005 at aoldot com
J.A.Prestwich V-Twin engines
Do you have any photos and information on the JAP racing V-twin engine called the Mark II buit in the late 40s I am artist and would like to have primary and timing side photos of this model for sketching. I believe Mr. Hagon used these in his sprint or drag racing bikes, but I can't find any data on these particular engines.

Thu Feb 23 2006
demarscomics2000 at aoldot com
J.A. Prestwich V-twin engines
Re: my first inquery on J.A.P. racing V-twins. I enclose a photo of an engine that I believe may be a Mark-II racing V-twin model, with duel magnetos. Perhaps someone can identify it as such...thanks.
L.A. California, USA

JAP Mark II racing V-twin.jpg
JAP Mark II racing V-twin

Wed Nov 23 2005
kingfish42 at
J A P Engine
What brand of motorcycle did Peter O'Toole drive at the beginning of the movie "Lawrence of Arabia"? It had a J A P Engine. Thank you. Robert

That motorcycle was a Brough Superior, and an account of Lawrence's association with the marque and his fatal crash may be found here:

Wed Nov 02 2005
1939 600CC SV J.A.P. ENGINE
I have a partially complete engine as above (ucz/g 6850/8) which I am trying to get some information about.Can you advise me?What machines were they fitted to? Where can I get a parts list or drawing as I need to know exactly what is missing. Did it have a dynamo or did it rely on acetylene lighting. What sort of magneto did it use?
Your help would be much appreciated.
Kind regards
David Griffiths

Fri Sep 23 2005
hailwood at hotmaildot com
JAP engines
I have what I believe to be three JAP motorcycle engines. I want to find out some information about them and would like the details of the Marque specialist please.

Mon Aug 01 2005
jcc.silveira at
Jap Engine with parallel cilinders
Has JAP Factory bild an engine with 2 cilinders parallel?
Can you send me a photo? What is the manufacturers year?
Thank you
José Carlos from Brazil

Could find no record of a JAP parallel twin. Ed. Tue Nov 08 2005
eddiebrant at aoldot com
Jap Motorcycle Engines
JAP made a 250cc parallel twin and a 500cc four in 1952. Look at the 1953 motorcycle show edition of "The Motor Cycle".

JAP also built a 500cc SV twin which was used in the AJW. See article in MotorCycling Dec 9 1948. Ed.

JAP 250cc parallel twin 1953.jpg
JAP 250cc parallel twin 1953

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