General Purpose Motorcycle

built for the British Ministry of Defence

By CCM Armstrong
Now owned by Harley Davidson

This page is Here to be of help to any who ride one of the Armies Motorcycles and wish to enjoy it to the full. From just saving money on servicing to Customizing to suit your needs as I have done.

Picture of a Standard Armstrong MT500 (not mine)

Some History On My Armstrong
( the Information is underneath so scroll By  the boring stuff )

   I have owned My Armstrong since summer1994  with 6000kms on the Clock  it lasted well till the beginning winter when the  Engine blew up completely destroying the piston, snapping the Gudgeon Pin in 2 parts (half is still wedged between the Crank Webs) splitting the Barrel. Investigation showed partial seizure due to Oil failure. 
   I boxed the bits and Mothballed the whole Bike Thinking I might be able to sell the frame and bits to cut my losses.  I got a New job and bought a Kwak Z1260, I still looked round for a new engine occasionally and never advertised the bits. The summer of 95 passed the Zed  was great,  looked good  very fast but the winter was a different story. Living out in the Sticks means narrow bumpy B roads covered in Mud and oil from tractors, Snow and Ice that might not get cleared for days and rarely gritted. 140bhp at the back wheel with road slick tyres was  No fun at all !!.

 The Armstrong had to come back !!   I looked in earnest now for a new Engine ,   New from Rotax was £4000, M & C Motorcycles Cricklewood was stockpiling any spare engines, and breakers just didn't have any , I managed to get a few parts of another broken engine.
  Then a I found an advert in MCN  under Rotax for a company specializing in the Engine, a quick phone call and they agreed to look at my pile of bits and try not to laugh to much.

After visiting and Talking to Them about the Problems I had ,and the Bits  I needed to replace as new . It was suggested to fit a larger Piston and Barrel from the 601 Rotax Engine, Flow and port the Head (the army spec is very restricted compared to a standard Rotax ) and fit with a higher lift Cam. Also increasing the Compression Ratio  ( Army Spec has 2mm less Stroke than the standard Rotax for the same height barrel).  The engine was re-built using the 2 donors and a mix of New and second hand Parts.

  It has taken 2 more years to finish the modifications with the changing of the Carburetor from the 30mm Amal  to a 36mm Delorto  and a custom Stainless Exhaust to let the engine breath properly. Until this was done the engine Ran badly (still Better in many ways than Standard).

Problems I found with the Standard specification of the Army Motor Cycle:
  Lack of ability to Cruise at a good speed Loaded (motorway)                                      Done
  Fuel efficiency  was way below the Quoted  figures (Army as well as Rotax)                  Done
  Could use more Power generally                                                                                  Done
  The Head Light is a waste of time                                                                                 Done
  The Pannier System could be improved or rather changed for my uses                            Started
  No pillion Pegs fitted                                                                                                     Done
  My version had a front Right Side stand ( I preferred the Rear left Side Stand )               Done
  It could be difficult to start , especially when Hot                                                           Done
  Reliability of the Army Spec Rotax  Engine after Military Service was Hit and miss         Done
  The Fuel Tank needed at least 1 more Gallon                                                                Waiting

MT500/570Detail Specification

WHITE = Army Manual      GREEN= What I have Found
RED= Modification I have done and the results

PERFORMANCE

• Acceleration : 0-100k.m.p.h (60 m.p.h.) - 9.5 sec    Dunno but its a lot quicker 6.5 ish
• Max speed : 150 k.p.h. (93 m.p.h. )   yes down hill with a pillion   95+  unstable over 95
• Braking distance : 50-0k m.p.h. to rest 13.1m
• Turning circle : 4.25m  (14ft)
• Minimum constant speed : 3/5 m.p.h. (5/8 k.p.h.)
• Water crossing : 0.5m (20 inches) approx.  don't even try it    
• Fuel consumption : 53m.p.g.        yeh right   32- 37mpg       55-65mpg now we are talking
• Range : 150miles approx     90-100miles if your lucky  165-185miles still needs another Gall

WEIGHTS AND MEASURES

• Dry unladen weight : = 161 kg (354lbs)  42%front, 52%rear  
• Kerbside Weight unladen Fully Fueled: 170kg (375lbs)
• Max. width : Across handlebar : 835mm
• Max. length : 2.140m
• Wheel base : 1.445m
• Ground clearance : Unladen 0.22m
• Fuel : Low octane (2 star) petrol        Unleaded          Unleaded      
• Fuel Capacity :  13 liters  ( 2.85Gal)                 Will increase by 1 Gallon soon
• Oil Capacity :  3.2ltrs  (0.7Gal)

ENGINE

• Type : Air-cooled single cylinder four stroke single overhead Cam
• Displacement : 481.3cc                         569cc       ( is thinking of a 640cc later )
• Bore & Stroke:  89mm x 77.4mm        92mm x 77.4mm   (Rotax normal stroke is 79.4mm)
• Power : 32 B.h.p @ 6200 RPM  about 25B.h.p  (at the back wheel)  39B.h.p so far  (65B.h.p for the 640)
• Torque : 38 Nm @ 5500 RPM
• Ignition : Solid state, auto advance, independent of alternator/battery system  
• Lubrication : Pressure feed to engine and g/box. Dry sump with integral filter
• Carburetor:  30mm Amal                     36mm Delorto  130 main  58pilot
• Air Filtration : Large paper element            Ram Air sponge (largest that will fit )
• Gearbox : Five speed integral with engine operating through multiplate wet clutch
           Stronger Clutch Springs
• Transmission : Self lubricated "O" ring chain running on hardened steel sprockets 5/8" x 1/4"
       Standard  17 tooth front and 47 tooth rear
        DID comp 520 chain and  Custom Aluminum Rear Sprocket 47 tooth with Pattern front  11 up to 19 tooth (normally 17-18)

ELECTRICAL

• Battery : 12 volt 5 Amp/Hr       14A/hr battery
• Alternator : 190 Watt 3 pole
• Headlight : Main beam/Dip 45/40 Watt. Park light 5W       100/80W Halogen
• Rearlight : Tail light 4W  5W. Stop light 10W (operated by front or rear brake)
• Direction Indicators : Front and rear 21W              10W system
• Horn : Front mounted

CHASSIS

• Frame : Welded steel box section, oil carrying with sealed taper roller steering bearings
• Sub frame : Welded steel tubular section bolted to main frame
• Swing Arm : Welded steel box section with sealed needle roller pivot bearings and cam type chain adjustment        Solid Bronze Bearings  
• Sump Protection : Pressed steel
• Footrests : Safety folding type     Pillion Pegs Added   (small people only)
• Seat : Single seat (emergency pillion rider capacity)   (pillion pad to extend seat)
• Forks : Telescopic, hydraulic damping, sealed     ( will add Comp forks soon with disc brake)
• Dampers : Telescopic, hydraulic damping, load adjustable, sealed   ( Olins are standard)
• Wheels :  Front 21" (90-90 41.54S) 24psi  28psi  Rear18" (400x18-64R) 22psi 25psi
• Brakes : 140mm front & rear drum type            ( 230mm disc with Brembo twin pot Caliper on Marrsochi Magnum 45mm Comp Forks)
• Plastics :
  Headlight cowl    Cut to allow removal over Brake cable and Rack fitted
  Mudguards      Enduro Mud Deflector fitted to the front
  Side panels          Harley Davidson panels  ( drives HoG Mad  :o)   )
  Chain guard
  Air filter box       Removed   for ram air filter
  Seat base
  Tool box
• Panniers : 2 x 23 liter capacity. Made from canvas to T9005B (Water and rot proof). Material double thickness throughout. Colour BS641. Will accept 2 x standard 5 gallon fuel containers    Yeh  right   ( they are Genuine Harley Accessories though, I got the sticker to prove it  )   single layer Canvas, waterproof for about 5 mins.   2 x Army 58' patt large packs for the back rack    2 x Army Resporater Bags for the tank  and  2 x Grenade boxes for the head light panniers and loads of Bungee's  (need to modify the racks to take 2x5 gall fuel cans  safely they sort of fit)
• Paint Specification : Colour Drab olive green     Matt and Satin Black (mostly Mud though)

Buying an MT500 is  fairly simple there are several  Dealers round the country who have bought them of of the army Sales Auctions and  some are always available privately in MCN or Trail Magazines:    The problem is getting a good one for a fair price  

Dealers Price from £750 - £1500 (i have heard of one  going for £3000)  
I wouldn't pay more than £950 - £1000 for a MOT able bike .   
£750 range is normally stripped of all lights, Panniers etc  for off road only.
You have to  look  the bikes over from top to toe, note any new looking parts  i.e. horn, switches, handle bars, leavers etc. All will be clean  and normally newly painted  with a coating of oil on the engine to make it shine. If you find Sand paint or they  say it was in the Gulf then ignore it ( it may be ok but most  where thrashed and full of sand ) Make sure you can hear it Run if they wont start it or cant , ignore it. Low mileage bikes are a good  start ( only a ruff Guide considered with the rest of the condition)

IF YOU DON'T KNOW WHAT TO LOOK FOR IN A BIKE TAKE SOME ONE WHO DOES

Dealers :-   Some i have tried  some are just  Addresses to me

M & C Motorcycles   (Expensive)   110 Cricklewood Broadway London NW2 Tel. 0181 450 050	LMS Ltd, (was AMBR) 5 The Holding, Watling Street, Weeford, Lichfield. WS14 0PL Loads of bikes good prices
Crook Brothers Blackburn Old Road Hoghton Preston Lancs PR5 0RX Tel. 01254 852660 Fax. 01254 853334	Force MotorCycles 92 Station Rd Barton under Needwood Burton on Trent Staffordshire BE13 8DS Tel: 01543 255 770 New Bikes

Private Buying : Prices  should range from about  £800 - £1200
  Again £800-£900 is a good price
Similar Checks to that of Dealer Bikes and other Second hand Bikes   hopefully the bike is reliable or the owner has sorted any problems from the dealer.  Check the Chain and Sprocket for wear, the Cam belt, and the spark plug. Again hear it  Run

For Private Ad's   try MCN  or Trail / off Road mags
There are usually some Armstrong's for sale on the Auto trader website.

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Once you  have got your Armstrong Home  and it Runs with Tax and MOT  you have to keep it on the road :   Spares and  parts can be very Expensive in a limited market. however there are ways round  some of the Costs  :o)  here are some useful numbers for bits :

CCM ARMSTRONG    for new bits Expensive But Fast  takes Credit Cards 01254691600

Dealers above  can sell second hand parts cheaper  AMBR is the best I have found  but doesn't take credit cards   nor does M&C  so takes a while to post and clear checks.

ANDOVER NORTON  (Rotax Main Dealer)  Importers of Rotax Engine spares
 Good for Cam Belts,  Oil Filters, Gaskets, Clutch Cables etc   Credit Cards  01703 366405

IN-CHAINS   Cheap Chains Sprockets (Will make rear Sprocket in  Aluminum for about £17)
                    ( Front Pattern Sprockets £8 ish ) D.I.D V6 'O' Ring Chain £50
                      The set I am running has lasted a year so far (5000mils approx) and still has plenty of life
                     Also good for     Tyres & Bearings  Fork seals etc         Credit Cards   01425 474800

SPORTAX   Engine tuning ,  all engine parts many second hand as new, Air Filters
                       Cam belts, Oil Filters, Cables etc and Many more
                       Has a wide Range of Armstrong parts (some prices are high some v /low )
                      Very Good advice and prices.  Fast Service  
                      Please Mention this Web site When you call thank you  01822 841063  

FORCE MOTORCYCLES   Specializes in Armstrong's and parts, including  upgrades
                                               Reasonable prices  and  a  Very Large  Range
                                               Mail Order So  Credit cards and a Quick service here      01543 255 770

Bearings Not in the Engine are best Bought from General Engineering shopes etc   I got My front wheel bearings from a tractor dealer and Garden Machinery Shop for a lot less than M/Cycle shopes sell the same bearing   (front Bearing No: 6204 2RS)  this works for most bikes.    IN-CHAINS Above is one of the Few who charge reasonable prices for Bearings (remember the MT500 has 6 bearings in the back wheel alone )
                     

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