To best select a replacement Mikuni Carburetor for your motorcycle please follow the steps listed out below. Due to the requirement of virtually every model of every year individually requiring a unique set of jets, our process below will allow you to correctly select a jet kit and other associated components to your personal requirement. TMX carbs are by far your best option for any 2-stroke engine if not restricted by VMX period racing rules.
On the main menu to the left of the page, hover over the carb listing for VM roundslide, TM non-pump or TMX 2-stroke carbs and then select from the drop down list the desired Mikuni carburetor size option for that particular carb type.
Click on each carb size and type you believe may suit your engine and remember don’t just look at similar size carbs as to that fitted on your bike as often some bikes that may have come standard with say a 32mm Amal carb may well run with VM carbs as big as 36mm.
Better venturi design and to a point a larger bore size equates to performance improvement where with Mikuni the progression ranges from the VM then TM and topped off with the TM pumper carbs on 4-stroke engines.
Do be careful if we don’t have an exact Mikuni carburtor suggestion for you bike, not to upsize too much as eventually this will cost you mid-range performance.
When clicking on any individual size Mikuni carb from the drop down list it will put you into a page showing not only the carb itself but also any item relevant to that carb, being jets, flanges, tuner kits, cables , throttles, air-cleaners and a range of carb to OEM air box adaptors to also suit. This also makes alternate jet selection easy for you if you have your own spec as only the type jets for that particular carb are shown.
When clicking on the carb itself, thoroughly read the carb description and check for size suitability. Then back arrow back in the carbs main page and go into the tuner kits, which show in the sales drop down list the jetting kits we have for confirmed suitable engines for that particular carb. Again thoroughly read the tuner kit description.
Basically if your engines not listed choose from the choice of others with a similar per cylinder capacity that you believe to be of comparable performance. This will give you a good jetting start point. Keep in mind a 1000cc twin is much the same as a 500cc single.
If you’re comfortable with the dimensions, suitability and an associated tuner kit for a carb, order it or otherwise please call us to further discuss on 0747712677.
Unlike many motorcycle manufacturers’ purpose modified versions (generally modified to comply with emission laws for worldwide sales), these Mikuni factory VM and TM carburetors are both 2 and 4 stroke compatible and are regarded by the Mikuni factory aftermarket racing division to be the best performing version of these carburetors ever made.
For VMX racers these are the most popular high performance singles carburetors in the sport of motorcycling. Mikuni’s VM Series round slide single carburetors have proven themselves as the performance standard for use in any single cylinder motorcycle and ATV applications for motocross, enduro and trail riding, to flat track racing and road racing on both 2-stroke and 4-stroke engines.
Performance features for the Mikuni VM Series Carburetors include a large selection of bore sizes for increased fuel mixture flow to match engine modifications. And the Mikuni VM Series offers a wide range of tuning components to allow precise fuel mixture metering in any application, at any throttle setting, under any riding conditions.
Tuner jet kits can be purchased separately for many different motorcycles as per the corresponding options. These kits consist of the suggested jets for changing that are not matching those factory fitted in the Mikuni VM38-9, they include an extra one size up and one size down main jet for tuning the main circuit due to fuel quality variations, altitude and climate. Testing and conformation of correct main circuit jetting can only be done by physically changing jets and WOT testing.
These tuner jet sets have been determined from thirty years of experience, customer feedback, plus research and development as the Australian Mikuni distributor. From time to time these may not be exactly right for every engine, usually due to changes to porting, compression or numerous other things that contribute to the requirement for additional fine tuning but as a rule our kits are spot on or a very close and useful starting point, but we give no guarantees and sorry do not release kit details or jet size information. If you have your own spec simply purchase the carb and buy any other required jets from the jet pages. This also applies to replacing jets in other Mikuni VM38’s as the 166 series needle jet and others items may not match and fit.
Keep in mind that these are suggested specs, and all tuning procedures, as found in our Tuning Tips section must be adhered to for the confirmation of any supplied jet’s compatibility with your engine.