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 Acme, AJW, Aliprandi, Alldays & Onions, Ambassador, Argentre, Ariel, Atala, Austral, Automoto, AWD, Bown, Bücker, Brough-Superior, Brown, Calthorpe, Chater-Lea, Corah, Cotton, Coventry-Eagle, De-De, DMW, Dollar, Dunelt, Eysink, Favor, Fusi, Ganna, Grindlay-Peerless, Hagon, Hazelwood, Imperia, Invicta, La Mondiale, Lady, Le Grimpeur, Lea-Francis, Majestic, Matchless, Meray, MGC, Morgan, New Imperial, New Map, Nut, OEC, OK-Supreme, Onoto, Osa-Liberty, Radior, Rex-Acme, Rover, Rovin, Royal Enfield, Royal Ruby, San Sou Pap, Soyer, Sparkbrook, Stylson, Terrot, Tornax, Trump, Ultima, UT, Verlor, Vindec, Wolf, York and Zenith.

JAP engines were also used in a wide range of industrial and other non-motorcycling applications including railcars and early Reliant 3-wheelers.
 

JAP 500 Speedway Bike 1949

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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 order...do you know of an earlier one?

More information under Chater-Lea

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Mon Jun 15 2009
ramavneri<at>013.net
PARTS
JAP 1911
Ineed parts: geer box and magneto and manual book for JAP v twin 1000cc 1911.

Thank u
Ram
Israel

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Sun May 31 2009
dgrinsh<at>hotmail.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

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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>optusnet.com.au> 

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

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Mon Apr 06 2009
markbaker<at>ihug.co.nz
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.
NEW ZEALAND

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Wed Mar 18 2009
leobortolotti<at>libero.it
JAP engine
JAP F2UH
I have this engine, can any one tell me about  and what bike it was?
many thanks
BOLOGNA ITALY
 

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Fri Jan 23 2009
tubeheadxtra.co.nz
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 

Christchurch 
New Zealand
 

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Tue Jan 20 2009
bullet101bigpond.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
Australia
...........
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 
 

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Sat Dec 20 2008
pethans14gmail.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
 

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Thu Nov 20 2008
tuta48szm.sk
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
Slovakai
 

............
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.

Juliana

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Wed Nov 19 2008
shoscombevaleyahoo.co.uk
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,
Melissa
Bath, UK

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

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Mon Oct 13 2008
iron_arielyahoo.ca
JAP manuals
Finally found a source for JAP manuals-
books4cars.com

Wade
Vancouver, Canada
English

See also Books and Manuals

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Thu Sep 18 2008
jekkalpost10.tele.dk
Oilpump
JAP engine 350 cmm sidevalve
Hi
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.
Denmark

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Mon Sep 15 2008
jarmo.mursulanetikka.fi
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
Finland

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Sat Aug 30 2008
terencecarringtonyahoo.co.uk
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.

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Tue Aug 26 2008
daiedegasyahoo.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
London
 

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Wed Feb 27 2008
comeon7sgmail.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

http://www.cameronracingengines.com
great white north

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Wed Feb 06 2008
micheal.atkinsonbtopenworld.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

JAP_Vtwin_Derbyshire

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Fri Dec 28 2007
lencambigpond.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

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Sat Oct 20 2007
neatherytsbcglobal.net
JAP in the movies
Unk.
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?
USA

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Wed Oct 17 2007
stubbs785btinternet.com
information about J A P engine
JAP v twin side valve engine number 32198
has any one any information about this engine? please
manchester

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Thu Sep 20 2007
ramavneri013.net.il
a rare v engine jap
1911 to 1914?
hi, 
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,
Ram
Israel

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21st Sept 2007
subject: Sheldon EMU
Email: toddjayporteraol.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
NJ (USA)
 
 

Nixon_JAP_1

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Tue Sep 18 2007
spykeraon.at
Jap school project
JAP  IY/I 1927
Hello!
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!
Austria

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Thu Sep 13 2007
kflcbigpond.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.
Australia

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Fri Jul 27 2007
wilkglennhotmail.com
Jap engines morgan cars

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

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

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Tue Jul 03 2007
jabbernccaol.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

JAP 2UH 2

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Fri Apr 20 2007
biffhezbtopenworld.com
identification
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
Fife
English
 

JAP sidevalve Fife

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Tue Feb 27 2007
debandstugmail
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

JAP_Howard_Rotovator

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Wed Feb 21 2007
hornetvipsapo.pt
Piston+rings for JAP 600cc industrial engine
JAP 600cc
Need help to locate source for piston assembly +rings for above engine
Lisbon

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Mon Feb 19 2007
pearsonrileyxtra.co.nz
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?

ta

NZ

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Fri Jan 26 2007
Jiwilliamsn
JAP CAM
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

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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
project
RG
[See forums. Ed.]

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Tue Jan 02 2007
g_skiltonhotmail
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.
london

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

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

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

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Sat Nov 04 2006
renegade.geordie.johnvirgin.net
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
English
.........
Hi, it is a Lucas mag, fitted to a J A P twin.
J.E.HOLMES
 

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Sat Oct 21 2006
luukrabberswanadoo.nl
enginge
J.A.P Diesel  D270
Have jou any information of thees JAP?
holland
 

JAP Diesel D270

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Tue Oct 10 2006
pethans1hotmail.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
Denmark
 

JAP Vtwin Denmark

Fri Jul 06 2007
pethans1hotmail.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 pethans1hotmail.com with information about this engine.
Thank you very much. Peter Hansen
Wisconsin USA

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Sat Oct 14 2006
bslarkbarbermuseum.org
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

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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

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

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Fri Sep 01 2006
rbbmarkeyyahoo.co.uk
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
IRELAND
 

JAP 600SV 1933

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Sun Aug 27 2006
hornetvipsapo.pt
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??
Sincerely
F.Martins
Lisbon

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Fri Aug 18 2006
chimpilinterra.cl
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

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Wed Jul 26 2006
happyhamraxyahoo
HELP
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
queensland
........................
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

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Fri Jul 21 2006
solanobtconnect
60 degree jap engines

were there any and what were they used for
london

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Thu Jul 13 2006
rushman69hotmail
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 rushman69hotmail. Many thanks.
London/New York

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Mon Jun 26 2006
CLLMCLAOL
JAP
I have an old jap speedway bike I have been racing, how can you tell what year it was made in?
VA

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Mon Jun 19 2006
moragfraserhotmail
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.

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. 

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Mon May 29 2006
neelix1961hotmail.co.uk
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
weymouth

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Thu Apr 06 2006
martyn.haguevirgin.net
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.
Sheffield

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Mon Mar 27 2006
davidmoryshotmail.co.uk
JAP Single cylinder
Serial number IY.WMS 86239
Hi
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.
Regards
David
Bretforton

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Thu Feb 23 2006
rosbaldistoningram.com.au
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

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Tue Feb 07 2006
concretesuaol
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

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Mon Feb 06 2006
t.eronengmail
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?
Finland

JAP 600cc OHV Engine UOR-W

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

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Mon Dec 26 2005
demarscomics2005aol
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
demarscomics2000aol
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

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Wed Nov 23 2005
kingfish42cox.net
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

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Wed Nov 02 2005
DAVID1950HOTMAIL.COM
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

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Fri Sep 23 2005
hailwoodhotmail
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.

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Mon Aug 01 2005
jcc.silveirauol.com.br
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

Tue Nov 08 2005
eddiebrantaol
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 250cc parallel twin 1953

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If you have a query about JAP motorcycle engines, or wish to share your knowledge of these classic British machines, please contact us!

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