I ship to Canada I ship to United Kingdom I ship to Australia I ship to Japan I ship to Belgium I ship to Germany I ship to Denmark I ship to Finland I ship to France I ship to Greece I ship to Italy I ship to Netherlands I ship to Norway I ship to Portugal I ship to Sweden I ship to New Zealand I ship to Spain I ship to Switzerland
Mikuni Tuning for British Twins
“Super-Tuning Mikuni ‘VM’

Carburetors and Intake Systems for British Motorcycles”

by Jeffrey Diamond

“Mikuni” name for reference purposes only.
Not affiliated with Mikuni Corporation.

Powered by FreeTranslation.com

    This is not an actual, physical booklet

    Want more performance from your classic Triumph, BSA, Norton, Royal Enfield or Matchless? Already have Mikuni carburetors, but don’t know how to adjust them? Doesn’t run “right”, and won’t respond to the changes you’ve made? Can’t make any sense of the original Japanese “instructions”? Looking for an affordable alternative to replacing or rebuilding your tired Amal Monoblocs or Concentrics? Have you heard that “Mikunis are great, but you need to be a rocket scientist to tune them”? This product will help you.
    While it’s true that the Mikuni VM has many more tuning components that an Amal Monobloc or Concentric, many types and sizes can be safely removed from the list of tuning variables. In this product I show you which ones to use, and why they work.

Mikuni VM Grand Prix Carburetor

    Mikuni VM Series &ldquosGrand Prix” carburetors have been used successfully on motorcycles for about 25 years. I’ve learned how to select and install them on older British pushrod models (beginning with my own 1970 Bonneville), including the T120, TR6, Thunderbird, Lightning Rocket, Thunderbolt, Commando, Atlas, Dominator, and more 500, 650, 750 & 828cc twins, as well as Gold Star, Ariel, Matchless, Norton & Velocette etc. and other 350 & 500cc singles.
    These carburetors are easy to find (click here to search for them on eBay: ) and tune, relatively inexpensive, small & compact. All sizes of this type have very similar components, with almost complete interchange within family size groups. The commentary in this product is limited to 26, 28, 30, 32, 34, 36 & 38mm VM carburetors, but does not cover the other CV, HS, RS, TM, TMS, TMX or OEM and proprietary models.
    This product includes specific choices of carburetor size and correct jetting for British engines, and gives you something you can really use, along with many helpful hints, comments, observations, data, etc. I can’t include instructions for your motor - there are too many variables - but the bike will definitely start, idle, run acceptably with good throttle response, and allow you to make those final adjustments to get it running really well.
    This is not like the generic manual that came with your carburetor, but begins where they leave off, and goes far beyond into fine tuning. Not an expert mechanic? You’ll still find this useful to identify what adjustments and parts you need. All parts are easily available all over the world at reasonable prices. If you’ve considered using a Mikuni, you should read this product.
    I guarantee that you’ll find information in this product you’ve never seen before, and that will help you plan and complete your carburetor conversion.
    Consider this: if this product saves you from making even a single mistake or bad purchase, or gives you one new idea, doesn’t that make this purchase worth while? The price is less than that of tuning components you may not need, and only a small fraction of what you will invest in the carburetors - plan more intelligently, and get better results.
    Contents are 42 pages (over 30,000 words), including 20 black & white illustrations & diagrams, plus 35 data tables including 9 jetting tables containing specific trial jetting suggestions for motors based on displacement and carburetor size: 17 entries for single carburetor, 24 entries for individual carburetors. This is far more specific content on these engines than any other source. The subject matter includes:
    Mikuni VM vs. Amal Monobloc & Concentric; differences in components and function.
    Carburetor selection; choice of size depending on displacement, head, intake manifold, cam timing.
    Tuning components; which parts can be adjusted or substituted to change mixture & when, where the parts are located, how to remove them, what the markings & sizes mean, which jet types are correct for each model.
    Needle jets: 2-stroke vs. 4-stroke, primary vs. bleed type.
    Needles sorted by length & marking; analyzing needle tapers, which needles are used in which carburetors & why.
    Adjusting mixture for hot cams, alternate exhaust systems including TT pipes, megaphones, diagnosing and correcting mixture based on symptoms, using a vacuum gauge.
    Dynamometer testing; how to prepare, tools & supplies.
    Tuned length intake manifold; how to make calculations for more power, including 5 Tables of pre-calculated manifold lengths based on cam duration, RPM, etc.
    Dual carburetor conversion; how to convert your single-carburetor twin (TR6, &c.) to dual carburetors, selecting size, how to make your own individual manifolds from common materials.
    Tunnel-ram intake manifold; more power for single-carburetor racers with theory, calculations and dimensions, including illustrations and 2 Tables of pre-set data.
    Tuned “Helmholtz” resonator; add an air box for power, discusses theory, calculation and dimensions, including 5 Tables of pre-set data.
    Increased airflow with the UFO and similar devices.
    Air cleaner; how to select & improve an air cleaner for more air flow.
    Jetting tables; specific trial (initial starting point) jetting suggestions for motors based on displacement, single or twin cylinder, single or dual carburetor(s), carburetor size.
    Velocity stacks and ram tubes; how they work, which ones are best.
    Jetting for alcohol; discusses jetting changes for methanol, ethanol, advantages, maintenance, safety.
    Sample Worksheet; to prompt you to keep records of changes vs. effects
    Most dimensions are given in fractional inches, decimal inches and metric for the convenience of tuners in all languages.





IBRARY has been a respected source of technical literature on older motorcycles since 1971. This information is not reprinted from other articles, magazines, or factory literature and is not available anywhere else, and not included in any of my other books; click here for other related titles: Victory Library booklets. I’ve also written booklets on Amal Concentric Tuning for British motorcycles: Amal Concentric Tuning for British motorcycles and Amal Monobloc Tuning for British motorcycles Amal Monobloc Tuning for British motorcycles, and one on the Linkert Model “M” bronze carburetor, used on all older Harley-Davidson & Indian models: Tuning the Linkert Model “M” bronze carburetor.
    Please note: this is not a repair manual. If your bike won’t start, the float bowl leaks, the spark plugs foul, &c. my product will not help you. It does not contain information on tune-ups, or explain how to remove, disassemble, clean, repair or rebuild the carburetor. If you do not already have this information please, don’t buy this product yet. If your engine is stock and you’re pleased with how it runs now, this product will not be of much use, although you might find it interesting. This is not a coffee table book, it is intended to be a research tool for those who want to make serious use of their Mikuni VM carburetors.

Total price: $9.95. This is not an actual, physical booklet, but an encrypted PDF file which you can read from any computer or lap-top using “Acrobat Reader”.

    The PDF format offers advantages over a printed product: the printed text and illustrations may be zoomed much larger permitting close inspection of fine detail. You can read it anywhere (doctor’s office, train station) on your smart phone or tablet.
    The file will be e-mailed to you within 24 hours of receipt of payment. There is no “hard copy”. There is no “print-out”. There is no tracking number. You must set your e-mail spam filters and preferences to accept mail from jdiamond@optonline.net. If you do not receive the file within 24 hours, the problem is your e-mail. If you don’t understand what this is, don’t purchase it, there are no refunds.

Click the button below to use your Visa or Mastercard to pay with PayPal


See these Victory Library booklets

I’m trying to locate some people I used to know; please click here for more details. Thanks!

Mikuni Parts

Order Form

Tech Papers



Tech Papers

Tech Papers


26mm, 28mm, 30mm, 32mm, 34mm, 350, 36mm, 38mm, 441, 500, 622, 624, 626, 627, 650, 689, 6DH2, 6DH3, 6DH4, 6DP1, 6DP5, 6DP17, 6T, 750, 750cc, 850, 828cc, 88, 932, 99, A10, A50, A65, A7, A75, adapt, adjust, adjustment, AHRMA, air jet, AJS, Amal carb, Amal carburetor, Atlas, B35, B44, B50, Bonneville, BS30/97, BSA 441, BSA 500, BSA 650, BSA A10, BSA A7, BSA B31, BSA B32, BSA B33, BSA B34, BSA B44, BSA DBD, BSA Gold Star, BSA Golden Flash, BSA Goldie, BSA GS, BSA RGS, BSA Rocket, BSA shooting star, BSA Victor, carburetter, carburettor, Norton Commando, Commando, compare, conversion, cutaway, cut-away, Cyclone, Daytona, Dominator, Enfield, Gold Star, Golden Flash, Goldie, GP, GS, Hornet, identify, idle, improve, install, jet, jet needle, jetting, kit, lean, Lightning, main, main jet, Manxman, Mark 1, Mark 2, Mark I, Mark II, Matchless, Matchless motorcycle, modify, Monobloc, Monoblock, N100.604, needle, needle jet, Norton, Norton 750, Norton 88, Norton 99, Norton Atlas, Norton Manxman, performance, pilot jet, pilot, R3, rich, BSA Rocket, Rocket, round slide, Royal, Royal Enfield, slide cutaway, slide, spigot, Super, T100, T100A, T100R, T110, T120, T120TT, T140, T150, T160, throttle-valve, throttle valve, Thunderbolt, Tiger, too lean, too rich, TR6, TR7, Triumph 3T, Triumph 3TA, Triumph 5T, Triumph 5TA, Triumph 650cc, Triumph 650, Triumph Bonneville, Triumph Daytona, Triumph T100, Triumph T100A, Triumph T100R, Triumph T100SS, Triumph T110 Bonneville, Triumph T120 Bonneville, Triumph Thruxton, Triumph Tiger, Triumph TR5, Triumph Trophy, Trophy 650, Trophy, tune, tweak, type 159, type 166, type 169, type 182, U.F.O., UFO, Velo motorcycle, Velocette motorcycle, Victor, VM22/210, VM28/486, VM34/17, VM4/042, X75, ZB34, VM34/05