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Andy Roberton AJS Stormer

AJS Stormer Main Page 

On this page you can find out where to buy vintage Stormer parts, obtain tips and information, check specifications, torque settings and contact us for technical help.

 

We still have tons of new Stormer parts in stock.

Some parts are New Old Stock, and some are newly manufactured.
Our GRP fuel tanks are made extra thick, from the latest ethanol resistant resin.
Our reproduction seats are thicker and far more comfortable than the originals.

We deliver parts all over the world.

All Stormer parts are available in our on line store.


If you cannot see what you want in our store, or you need help, contact us, and we'll be happy to help and advise you.

250 Stormer Con-rod
Norton Villiers 250 scrambler 1967

It is over 55 years since the Stormer's first year of production.
The Y4 was inaugurated in 1968. The first private rider to score a win was Alan Arnott on Sunday 16th March 1969 at The Kiwi Club's scramble at Bulford Down, Wiltshire.
Malcolm Davis won 250cc British Championships in 1968  and again in 1970, Andy Roberton brought the Stormer home in second place.
Read the amazing story of the AJS Stormer and the people who designed, developed and raced it, as told by the words of Cliff Stevens.

 Gear Ratios, Primary Drive Ratios and Primary Chain
Close Ratio is used for Scrambles - Wide Ratio is used for Desert Racing and Trail use. 

Stormer gear ratios
Torque Wrench

 Common Stormer Torque Settings
 

  • What can I ride?
    Unless you have a valid driving licence AM, A1 or A2, you will need to complete CBT (Compulsory Basic Training). Besides being an invaluable skill to keep you safe on the roads, learning and obtaining the certificate is fun! Many training schools have AJS bikes and this gives you an opportunity to really get the feel of an AJS bike before you decide to buy one. So, in a nutshell, if you are 16 or 17 and have no driving licence you need: a Provisional Licence and achieve CBT. You are required to display L plates and you cannot carry a passenger until you pass your test. At 16 you can ride up to a 49cc "moped" and at 17 you can ride up to 125cc. To apply for a provisional driving licence follow this link. Contact the DVLA
  • Can I purchase my AJS on finance or by a hire purchase arrangement?
    Many of our dealers offer finance packages. Contact your local AJS dealer to see what they can offer you. ​
  • Do I need to insure my AJS?
    Yes you do. It is a legal requirement. There are many insurance companies that specialise in motorcycle and scooter insurance. Shop around for a good deal. Your dealer may also be able to make recommendations. If your preferred insurance company is having trouble finding your AJS on their database, contact us for the ABI code. This will ensure they can easily identify it. Our preferred insurer is Bike Sure click here for a quote
  • Can I buy an AJS with confidence?
    Yes. AJS Motorcycles Ltd. is a member of the MCIA and operates according to the MCIA code of conduct. The Motorcycle Industry Association (MCIA) has looked after the interests of the motorcycle industry for over 100 years. The MCIA's Buy With Confidence programme has been developed to provide peace of mind to customers purchasing a motorcycle, scooter or moped manufactured or imported by a member of the MCIA. AJS Motorcycles Ltd. is fully committed to delivering the highest levels of customer care. As a subscriber to the Motorcycle Industry Association’s Buy With Confidence programme, an Alternative Dispute Resolution (ADR) service is offered in the unlikely event you are not satisfied with the outcome of a dispute. The ADR service is administered by and independent and impartial provider ‐ the National Conciliation Service, First Floor, 2 Allerton Road, Rugby CV22 0PA. https://www.nationalconciliationservice.co.uk/
  • Is my AJS built to EEC standards?
    All road going AJS motorbikes and scooters are built and certified to European standards. This ensures safety requirements are met, all construction and use regulations are met, current emission levels are met and conformity of production is in place.
  • Can I buy an AJS in a box for home delivery?
    No, that would be a bad idea. AJS motorbikes and scooters can only be purchased from one of our authorised dealers. This is to ensure a thorough Pre Delivery Inspection is carried out, a proper customer handover procedure is performed and you have somewhere local to go to for your after sales service. Your dealer will explain machine operation, maintenance schedules, warranty and after sales arrangements, machine care and can advise you of what safety clothing you should wear. ​
  • Does my AJS come with a warranty?
    Yes, your AJS is protected by a warranty that will cover the cost of repair or replacement of any parts that fail due to a manufacturing defect. The warranty is transferable to another owner and is implemented by the dealer you purchase your bike from. See the important terms and conditions here.
  • What are the service intervals for my new AJS?
    Download the service schedule here.
  • Where can I purchase spare parts for my AJS from?
    You can order spare parts from your AJS dealer, you can buy spare parts from our on line shop or you can email our spare parts department: spares@ajsmotorcycles.co.uk You can pay for spare parts by: bank transfer, all major credit/debit cards or Paypal. We have thousands of parts in stock for AJS models dating back to 1969. Be sure to have your 17 digit VIN number available when you order parts by email or by phone.
  • Where can I get an AJS Owners Manual from?
    Each new AJS motorcycle or scooter is supplied with an Owner's Manual. If you did not receive an Owner's Manual with your new AJS motorcycle or scooter, contact your supplying dealer and request it. It should be supplied free of charge. If you have lost or mislaid it, you can purchase a replacement from our on line web shop or contact us here.
  • Can I get a workshop manual for my AJS motorcycle or scooter?
    We can supply generic workshop manulals which cover motorcycle and scooter basics. You can purchase them from our on line web shop here. Check your Owners manual for basic information.
  • What is the tappet/valve clearances for my AJS motorcycle or scooter?
    We recommend inlet and exhaust clearances of 0.15mm (0.006")
  • What oil do I use in my AJS motorcycle or scooter?
    We recommend Fuchs Silkolene oils. You can buy these oils from your local dealer or from our online shop Note: See your Owner's Manual for specific information about grades and quantities.
  • What tyre pressures should I use on my AJS motorcycle or scooter?
    Please check on our web site at the bottom of the information page for the relavant vehicle. Also, you can check in your Owner's Manual.
  • What do the initials A.J.S stand for?
    The Stevens brothers; Harry, George, Jack and Joe were the sons of a precision engineer, Joe Stevens who lived and worked at Wednesfied, Wolverhampton, England. The brothers had an interest in technology and motorcycles and made their first Stevens motorcycle with a Mitchel engine in 1897. They then went on to manufacture engines. Later, to differentiate the new motorcycles from the products of the proprietary engine manufacturing company a new name was needed. A.J.S was chosen after the initials of the eldest brother; Albert John (Jack) Stevens, as he was the only brother who had two Christian names. Photo: Retreat Street Works in 1913. Courtesy of Ray Jones. http://www.historywebsite.co.uk/Museum/Transport/Cars/AJSfactories/RetreatStreet/RetreatSt.htm
  • How should I clean and polish my AJS motorcycle or scooter
    Your AJS Motorcycle or Scooter will need regular care and cleaning to maintain its good looks. In return for your effort you will surely experience pride and satisfaction knowing your motorcycle not only looks good, but has been regularly checked during the cleaning process. Note: If you park or use your motorcycle in salty locations, such near to the coast or if you travel on coastal roads or use your motorcycle in the winter when the roads have been salted, extra cleaning and corrosion preventing measures will be necessary. If you store you motorcycle whilst salt is on its surfaces, the salt will absorb moisture from the air and cause accelerated and aggressive corrosion. This is especially true if you store your motorcycle outside or under a cover. Never leave salt on your motorcycle. Salt is the enemy of motorcycles! Before You Start – Prepare Yourself. Remove your wrist watch (it can scratch even the best quality paintwork), as will rings or any bracelets you might be wearing. You will need a soft clean sponge and soft nylon bristled brushes for the non-bodywork areas and a separate soft sponge and good quality cleaning cloths for the painted panels. A genuine chamois leather is good for drying wet body panels and windshields to leave a smear free surface. Never use household cleaning products such as washing up liquids, washing machine or dishwasher detergents. Most household cleaning products have highly corrosive salt diluted into them. Only use good quality automotive shampoos and automotive de greasers. Never use "Truck Wash" or highly concentrated high powered detergents as these can stain the bodywork and aluminium parts. Always follow the manufacturer’s instructions. Never use abrasive items such as wire brushes or wire wool, scouring pads etc. Generalities Frequent, regular cleaning is an essential part of maintaining your AJS motorcycle. If regularly cleaned, the appearance will be maintained for many years. Always wash your motorcycle with clean cold water immediately after you have ridden on salty roads or have exposed your motorcycle to corrosive conditions such as in snow, slush or a sea breeze. Salt can corrode your motorcycle in a very short period of time. Extra protection from salt can be gained by applying Scottoiler FS-365 or ACF50 to bright metal parts. Under the terms of your motorcycle warranty, cover is only provided against the corrosion of certain items, the owner is expected to observe this maintenance advice, which will safeguard against corrosion and enhance the appearance of the motorcycle. Prepare the Bike for Washing Before washing, precautions must be taken to keep water away from following places: - Rear opening of the silencer(s) / mufflers: Cover with a plastic bag secured with rubber bands or insert rubber plugs. Switch housings on the handlebar: Cover with plastic bags or cling film to prevent excessive water getting into the wiring beneath the switch cubes. - Ignition switch: Cover the keyhole with blue –tack to stop water draining into the electrical connections within the switch assembly. Avoid excess water in the following places: - Instruments. - Brake cylinders and brake callipers. - Under the fuel tank. - Head stock bearings. - Air intake duct. - Under the seat. DO NOT use a pressure washer. Only use a bucket of water or low pressure hose. Replenish the water in the bucket if it becomes contaminated with dirt and grit. When You Wash Your Bike Ensure the bike is cold. Start at the top of the bike. Soak those areas that have dead insects etc and leave them for a few minutes, they will come away once the water has soaked in. Gently use a soft nylon brush to dislodge the most stubborn debris. When you think you have dislodged the dirt, use clean cold water to rinse the bike down. This will swill away any loose dirt still settled on the bikes various surfaces and rinse away any traces of shampoo, which may cause unsightly staining if not removed. Wipe the wet bodywork with a clean damp chamois leather to dry off and remove water stains. After Washing Remove plastic bags/cling film/rubber plugs and tape, and clear the air intakes. Lubricate all the pivots. Do not allow water to stand on the machine as this will lead to corrosion. Test the brakes before motorcycle operation. Drive slowly and apply the brakes before normal road use is resumed. Dry off with a large, clean microfiber cloth. Once the bike is dried, you can apply waxes and polishes. Many Automotive bodywork polishes will be suitable for painted panels. A light lubricant such as WD40, Silkolene Pro-Prep or similar is fine for most non-painted bodywork area. WARNING Do NOT apply light lubricants or waxes to the brake discs. Loss of braking power could occur and an accident could result. Do not apply the light lubricant to, meters or the exhaust system. (see below for exhausts). Unpainted Aluminium Items Clean bare unpainted aluminium items regularly, in particular after use in adverse weather, where the components must be hand washed and dried each time the machine is used. Warranty claims due to inadequate maintenance will not be allowed. Bare unpainted aluminium can be polished with appropriate metal polish such as "Solvo Autosol". To test if a surface is lacquered or not, apply metal polish with a clean dry cloth and gently rub. If the cloth quickly turns black, the item is bare metal and not lacquered or painted. Treat lacquered or painted surfaces like the body work. Apply wax polish. Chrome painted plastic Use wax polish. Abrasive chrome cleaner should not be used on chromed plastic parts. Cleaning of the (chrome plated) Exhaust System WARNING The exhaust system must be cool before washing to prevent injury from burns. All parts of the exhaust system of your motorcycle must be cleaned regularly to avoid deterioration of its appearance. These instructions can be applied to chrome or stainless steel components alike. Water spotting will occur if the exhaust is washed when hot or warm. Exhaust Washing Prepare a weak mixture of water and automotive shampoo. Wash the exhaust system with a soft cloth. Do NOT use an abrasive scouring pad or steel wool. They will damage the finish. Rinse the exhaust system thoroughly. Ensure no soap or water enters the mufflers. Exhaust Drying Dry the exhaust system as far as possible with a soft microfiber cloth or leather chamois. Do not run the engine to dry the system or white spotting will occur. Caution The over use of abrasive chrome cleaners such as "Solvol Autosol" may damage the chrome exhaust system and should be avoided. Only use "Solvol Autosol" to remove small stubborn burn marks, for example if a pillion passenger's shoe has melted onto the pipe or if a section of the pipe has "blued" or shows signs of corrosion. It is recommended that regular protection be applied to the exhaust system as this will both protect and enhance the system’s appearance. On Reflection... Regular cleaning is essential to keep your bike looking good. Not only does it gives you the satisfaction of having a good looking motorcycle, but you also get technically closer to the bike, noticing how things are connected and operate, which parts move in what direction. Your technical appreciation and awareness will grow. You will become more confident with the day to day mechanics of your machine. Summary. 1. Prepare yourself, your equipment and use only high quality automotive cleaning agents. 2. Prepare the bike for washing. 3. Wash the bike and leave to soak. 4. Rinse the bike with clean, cold water. 5. Dry the bike using a microfiber cloth or chamois. 6. Apply Scottoiler FS-365 or ACF50 corrosion inhibitor to metal parts and wax polish to painted surfaces and chromed plastic parts.
  • What fuel do I use in my AJS motorcycle or scooter
    AJS Fuel Statement (updated September 2021) AJS motorcycles and scooters over 50cc and registered on or after *1st January 2017 are OK to use E10 fuel. Any motorcycle or scooter which is under 51cc or uses a carburetter, or was registered before 1st January 2017, is not compatible with E10 fuel and must use E5 petrol.*Euro 4 and later Click here for UK Governemt Fuel Advice Note: If you have a 1970's AJS Stormer, you will need a fuel tank manufactured from the latest GRP resin for it to be resistant to modern fuels. see www.ajs-shop.co.uk
  • How can I tell if my Regal Raptor engine has a balance shaft or not?
  • What needs to be done when servicing my AJS?
    Download the service maintenance sheets from here
  • How do I measure my chain?
    Chains are measured in inches. The size of chain is denoted by a three digit code eg: 520 This code refers to the combination of Pitch x Width. Pitch (the centre distance of two adjacent rollers) Roller Width (the width of the rollers) Common Chain Sizes: Chain Size-----Pitch---------Roller Width 415------------1/2"------------3/16" 420------------1/2"------------1/4" 428------------1/2"------------5/16" 520------------5/8"------------1/4" 525------------5/8"------------5/16" 530------------5/8"------------3/8" Further notes about chains. 1) There are standard chains, just the basic chain that needs regular maintenance. 2) Heavy Duty chains, made from thicker steel. These tend to wear better than standard chains, but are heavier in weight. 3) O-Ring chains, which are usually Heavy Duty and incorporate a rubber O-Ring each side of the roller to seal in lubricant. Maintenance Keep your chain well lubricated and adjusted correctly. Check regularly for correct adjustment and roller damage. Make sure the joining link has its spring clip fitted the correct way round. The closed end of the clip should lead. A worn chain or a badly adjusted chain can be dangerous. Replace a worn chain together with new sprockets. Visit our web shop: www.ajs-shop.co.uk
  • What front fork oil do use in my AJS motorcycle or scooter?
    Please check on our web site at the bottom of the information page for the relavant vehicle. You can buy these oils from you local dealer or from our on line shop

Model: Y4, Y4 MK,2 250 Stormer 1968 - 1974 

Standard Technical Data for MX use, without "Works Tuning"

 

Engine

Bore: 68mm

Stroke: 68mm

Capacity: 247cc

Compression Ratio: 11:1 

Port Timings: Exhaust: 180 deg, Transfer: 135 deg, Inlet: 152 deg.

Ignition Timing At Piston: 2.5mm (.1 ins.) At Crankshaft: 20 - 22 deg.

Contact Breaker Gap: .38mm (0.015 ins.) 

Spark Plug NGK B8ES - Champion N3 Plug 

Gap: .635mm (.025 ins.) 

 

Transmission 

Engine Sprocket: 20T 

Clutch Sprocket: 43T 

Gearbox Sprocket: (520) 13T 

Rear Sprocket: (520) 61T 

Gear Ratios (Close Ratio): 1st - 2.00 2nd - 1.51 3rd - 1.25 Top - 1.00

 

Carburetter 

The Amal Mk1 32mm "932" was fitted as standard, however we recommend fitting the Amal Mk2, 34mm for standard Stormer 250 engines and Mk2 38mm for "Works Tuned" engines. 

(Check for eligibility with your club). 

 

Amal 932 Settings:

Throttle valve: 3 Main Jet:

280 Needle Jet: 107 Needle position:

Middle Pilot Jet: 20

 

Capacities

Fuel Tank: 1Imp Gallon, 2.4 US Gallons, 9L.

Gearbox: 1pint, 20 fl oz, 

Primary Chaincase: 0.57 pint, 7.5fl oz, 210cc 

Front forks (each leg): 0.57 pint, 7.5fl oz, 210cc 

 

Lubricant Types (recommended)

Fuel Mix: Silkolene Casterene R40 @ 32:1

Gearbox: Silkolene Medium Weight Gear Oil,

E.P.90 Primary 

Chaincase: Silkolene Light Weight Gear Oil sae 10/40 75w or Silkolene 10w Front Fork Oil If using our high quality primary chains #27799B.

Rear Chain: Silkolene Chain Lube.

 

Other data

Steering Head Angle: 30 deg.

Fork Trail: 5.15ins.

Pistons Piston Skirt Diameters: 67.913mm/67.887mm (2.6738/2.6727 ins.)

Piston Clearance in bore: .076mm/.89mm (.0025/.003 ins.)

Ring Gap: .178mm/0.305mm (.007/.012 ins.)

Con-Rod length, centres: 126.97mm/127.025mm (4.999/5.001 ins.)

Small End Bush Bore:17.47mm (.675 ins.)

Model Y5, Y50 370, 370 Stormer

1970 - 1974

Standard Technical Data for MX use without "Works Tuning"

 

Engine

Bore: 83mm

Stroke: 68mm

Capacity: 368cc

Compression Ratio: 11:1

Port Timings Exhaust: 180 deg, Transfer: 130 deg, Inlet: 170 deg.

Ignition Timing At Piston: 2.5mm (.1 ins.) At Crankshaft: 20 - 22 deg.

Contact Breaker Gap: .38mm (0.015 ins.)

Spark Plug NGK B8ES - Champion N3 Plug Gap: .635mm (.025 ins.)

 

Transmission

Factory set-up. Engine Sprocket: 24T

Clutch Sprocket: 40T

(we use Engine Sprocket: 20T

Clutch Sprocket: 43T)

Gearbox Sprocket: (520) 12T

Rear Sprocket: (520) 65T

Gear Ratios - Wide Ratio. (We use the 250 Transmission set-up and a C.R. gearbox) 1st - 2.52 2nd - 1.66 3rd - 1.25 Top - 1.00

 

Carburetter

The Amal Mk1 34mm "1034" was fitted as standard, however we recommend fitting the Amal Mk2, 36mm for standard Stormer 370 engines and Mk2 38mm for "Works Tuned" engines. (Check for eligibility with your club).

 

Amal 1034 Settings:

Throttle valve: 2.5

Main Jet: 370 - 410

Needle Jet: 108

Needle position: middle

Pilot Jet: 25

 

Capacities

Fuel Tank: 1Imp Gallon, 2.4 US Gallons, 9L.

Gearbox: 1pint, 20 fl oz,

Primary Chaincase: 0.57 pint, 7.5fl oz, 210cc

Front forks (each leg): 0.57 pint, 7.5fl oz, 210cc

 

Lubricant Types (recommended)

Fuel Mix: Silkolene Casterene R40 @ 32:1

Gearbox: Silkolene Medium Weight Gear Oil, E.P.90

Primary Chaincase: Silkolene Light Weight Gear Oil sae 10/40 75w or Silkolene 10w Front Fork Oil If using our high quality primary chains #27799B.

Rear Chain: Silkolene Chain Lube. 

 

Other data

Steering Head Angle: 30 deg.

Fork Trail: 5.15ins.

Pistons Piston Clearance in bore: see note

Piston length at the rear: 73mm

Ring Gap: .178mm/0.305mm (.007/.012 ins.)

Con-Rod length, centres: 26.97mm/127.025mm (4.999/5.001 ins.)

Small End Bush Bore:17.47mm (.675 ins.)

Model Y51, 410, 410 GP, 410 Stormer
1971-1974
Standard Technical Data for MX use without "Works Tuning"


Engine 
Bore: 83mm
Stroke: 74mm
Capacity: 400cc
Compression Ratio: 11:1
Port Timings: Exhaust: 180 deg, Transfer: 130 deg, Inlet: 154 deg.
Ignition Timing At Piston: .125 ins/3.2mm At crankshaft: 20-22 deg. 
Contact Breaker Gap: .38mm (0.015 ins.)
Spark Plug NGK B8ES - Champion N3 (unless a 370 conversion, in which case a short reach plug will be used such as NGK8HS)
Plug Gap: .635mm (.025 ins.)

Transmission 
Engine Sprocket: 24T 
Clutch Sprocket: 40T 
Gearbox Sprocket: (520) 12T 
Rear Sprocket: (520) 65T 
Gear Ratios-Wide Ratio. (The C.R. gearbox may be used. See 250 data.) 1st - 2.52 2nd - 1.66 3rd - 1.25 Top - 1.00 

Carburetter
The Amal Mk1 34mm "1034" was fitted as standard, however we recommend fitting the Amal Mk2, 38mm for standard Stormer 410 engines and "Works Tuned" engines.

Amal 1034 Settings:
Throttle valve: 2.5 
Main Jet: 370 - 410 
Needle Jet: 108 
Needle position: middle 
Pilot Jet: 25 

Capacities
Fuel Tank: 1Imp Gallon, 2.4 US Gallons, 9L.
Gearbox: 1pint, 20 fl oz, 210cc 
Primary Chaincase: 0.57 pint, 7.5fl oz, 210cc 
Front forks (each leg): 0.57 pint, 7.5fl oz, 210cc

Lubricant Types (recommended)
Fuel Mix: Silkolene Casterene R40 @ 32:1
Gearbox: Silkolene Medium Weight Gear Oil, E.P.90 
Primary Chaincase: Silkolene Light Weight Gear Oil sae 10/40 75w or Silkolene 10w Front Fork Oil If using our high quality primary chains #27799B.
Rear Chain: Silkolene Chain Lube.

Other data 
Steering Head Angle: 30 deg.
Fork Trail: 5.15ins.
Pistons Piston Clearance in bore: see note
Piston length at the rear: 75mm
Ring Gap: .178mm/0.305mm (.007/.012 ins.)
Con-Rod length, centres: 139.67mm/139.725mm (5.499/5.501 ins.)
Small End Bush Bore:17.47mm (.675 ins.)

 

Errors and omissions expected. For further hep contact us.
All content on this web site is copyright and may not be reproduced without permission from AJS Motorcycles Ltd.

AMAL carburettors AJS-Shop
AMAL carburettors AJS-Shop
AMAL carburettors AJS-Shop

How to set up, re-jet and pretty much everything else you might want to know about AMAL carburetters, download the PDF information document.

Fluff Brown AJS

Remembering Fluff Brown

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