Motocross Or Dual Sport?
Honda, Yamaha and Kawasaki are not currently making any street legal Supermotos but it’s worth considering using one of their excellent motocross or dual sport bikes for a Supermoto conversion.
Converting a motocross into a Supermoto is much more complex, costly and time consuming than converting a dual sport that is already road legal.
But if you are mechanically and electrically minded it’s often not as challenging as you may think.
Note: Always thoroughly research what is involved in converting your make/model before parting with your hard earned cash.
Spend the minimum amount of money to get your motocross road legal before the full conversion. There’s no point in buying lots of goodies only to find out you can’t get a log book (V5C) or MOT for some reason.
In the UK you will need to contact the manufacturer and pay for a ‘Certificate of Newness’ for your motocross.
When the certificate arrives check to see if there is a NOVA reference number on it. If there isn’t you will need to contact NOVA and get the bike added to their database.
Once this is completed you will receive a NOVA reference number. Note: NOVA will require a receipt/invoice for the motocross.
The next stage is to get a MOT for the bike. You will need to show the Certificate of Newness to the tester. As there is no log book they will use the frame number instead.
Going for a ‘daytime’ MOT will save you the hassle of having to install lights etc.
For the ‘daytime’ MOT you only need road legal tyres, a horn and a rear reflector. Although it’s best to clarify this at your local MOT station as this can sometimes be a grey area.
With the MOT complete you can then apply for a V55/5. When the log book arrives you can finally purchase a number plate and insurance.
Now the motocross is fully road legal let the Supermoto conversion begin!
The Supermoto conversion list below is a general guide covering the main items to convert a motocross into a Supermoto.
As dual sport motorcycles are already road legal you should only require the Top 17 items on the list.
Supermoto Conversion List
- Supermoto wheels: both wheels are normally 17″
- Inner tubes: required for most spoked wheels
- Road tyres: 3.5″ wide for the front and 4″ – 5″ wide for the rear
- Wheel spacers: may be required
- Gearing ratio: i.e. front sprocket 13T & rear sprocket 44T
- Chain: narrower chain may be required to avoid tyre rub
- Larger front disc: normally 320mm diameter
- Front brake calliper relocation bracket: required for calliper
- Upgraded front brake master cylinder: improved braking
- Braided hoses: improved braking
- Footpegs: Supermoto style, shorter and higher + slider
- Front fender: Supermoto fender is more aerodynamic
- Fork guards: trimming may be required for wider tyre
- Front fork brace: providing additional stability
- Stiffer suspension: new suspension setup required
- Kickstand: aftermarket stands may require shortening
- Speedometer: recalibration required on dual sport
- Street legal exhaust system: motocross exhaust is not street legal
- Larger radiator: more efficient cooling
- Upgraded stator: standard AC motocross stator will not power a lighting system
- Rectifier/Regulator: converts AC to DC
- 12V battery: adding a battery for the additional lighting system
- Wiring harness: required for the additional lighting, speedometer and so on.
- Key ignition switch: not necessary but recommended
- Headlight + switches: required for a full conversion
- Indicators + switch: required for a full conversion
- Rear brake light + front & rear brake switches: required for a normal UK MOT
- Handguards: not necessary but recommended
- Axle sliders: not necessary but recommended
- Mirrors: not necessary but recommended
- Horn + button: required to be street legal
- Rear reflector: required to be street legal
- License plate + bracket: required to be street legal
- Go test ride that Supermoto:
Whether or not you go for all the bells and whistles above, the basic conversion should include – correctly sized wheels with decent tyres, upgraded braking, correct suspension setup, optimal gearing for the road and having the bike road registered.
With regards to the suspension it’s important to have it set-up correctly. Depending on the make/model you may find the springs and valving will need to be replaced. Irrespective of this, the preload, rebound and compression settings will all need adjusting to suit Supermoto riding.
With smaller diameter wheels the ride height is lowered which in turn improves road handling characteristics. For further improved handling you might consider adjusting the front fork position through the triple clamps.
Suspension Terminology
Preload: The spring tension that is based on your weight.
Damping: How fast the spring squashes down and then returns to the normal position.
Compression: How fast the spring squashes down.
Rebound: How fast the spring returns to the normal position.
Supermoto Wheels
At the top of the Supermoto conversion list are the wheels and tyres. This is really what separates a Supermoto from a motocross. Choosing these correctly for the conversion is essential.
Just by looking at a motocross swingarm it’s easy to see the clearance is not designed for really wide tyres.
Although it looks cool having the widest rear tyre possible, if it’s going to cause chain rubbing or even worse interference with the swingarm then it’s not the right choice.
So when choosing wheel size always do plenty of research on the correct fit for your bike. If there’s any doubt it’s better to err on the side of caution and go for a narrower wheel.
A set of wheels can start from £600 and go up to £2000 and will be the most expensive part of the conversion. There’s quite a few companies that manufacture specific Supermoto wheels.
One of the popular wheel sets among Supermoto riders on and off the track is the Excel rim on a Talon hub. Both companies are very well established and trusted for quality throughout the motocross industry.
Another popular choice is Warp 9 Racing, offering fully customizable wheel sets. Which include the rims, hubs, disc, sprocket and colour. These wheels are ideal for riders who will be mainly using their Supermoto for street use.
SM Pro also manufacture some excellent Supermoto wheels and are one of the leading suppliers of MX wheels in the UK and Europe.
Haan Wheels is a company in the Netherlands that manufacture Supermoto wheels. Haan design their own hubs to go with Excel rims and offer many different colour combinations.
If you prefer the look of cast wheels compared to spoked, then Marchesini produce some stunning looking Supermoto wheels. These are not cheap but holy moly look awesome!
Cast wheels are lighter than spoked and also use tubeless tyres which again is a weight saver.
These wheels are stiffer than spoked which can improve rider stability under braking and allow for quicker directional changes. However, this lack of flexibility means they aren’t so suitable for big jumps and tough off-roading.
Supermoto Wheel Size
For general street use and some off-roading a 17″ x 3.5″ front wheel with a 17″ x 4.25″ rear wheel would be OK and offers a broad range of tyre choices.
Example tyres for these wheels would be the Continental Attack SM: 120/70R17 front and 150/60R17 rear.
If you were looking to race your Supermoto then a 16.5″ x 3.5″ front wheel with a 17″ x 5″ rear wheel would be better suited.
The advantage of a 16.5″ front wheel is you’ll get quicker turning response and less chatter. The wider rear offers better tyre contact.
Note: A 16.5″ wheel will limit tyre choice for the road.
Yamaha YZ450F - 2014 Model
The YZ450F is Yamaha’s flagship motocross and with that in mind a full Supermoto conversion would be required for street use.
The 2014 Yamaha YZ450F is a completely redesigned motocross machine from the ground up compared to the previous model.
Yamaha aimed to create what they call The Ultimate YZ by combining ease of cornering and a usable power band with a chassis that is lightweight and compact.
The 2014 YZ450F’s all-new engine is still the basic design — a DOHC motor with a four-valve head and rear-canted top end. This has received several revisions including a new piston, cylinder head, intake camshaft, intake and exhaust valves and a wrap-around exhaust system.
- Engine: 449cc single-cylinder, 4-stroke, liquid-cooled
- Max. Power output: 58 HP @ 9,000 rpm
- Max. Torque: 45 Nm @ 7,000 rpm
- Gearbox: 5 speed
- Seat height: 1000mm
- Weight: 110 kg
- Price: £3,500 – £4,500
KTM 500 EXC-F - 2019 Model
The KTM 500 EXC is one of the very best dual sport motorcycles ever made and when converted into a Supermoto it transforms into an absolute beast.
As previously stated, being a dual sport motorcycle will make the Supermoto conversion a much simpler process.
Many years of development have gone into the latest generation EXC-F chassis and KTM have managed to get the chassis and suspension to work together seamlessly.
The KTM offers brilliant handling, fantastic build quality and the engine is a total powerhouse. This is one of the very best Supermoto conversions out there.
- Engine: 510cc single-cylinder, 4-stroke, liquid-cooled
- Max. Power output: 41 HP @ 7,800 rpm
- Max. Torque: 40 Nm @ 6,690 rpm
- Gearbox: 6 speed
- Seat height: 960mm
- Weight: 106 kg
- Price: £8,200
Honda CRF450R - 2009 Model
The Honda CRF450R is one of the best motocross bikes on the market and if converted will make a fantastic Supermoto.
The 2009 CRF450R had a new engine design compared to previous models and comes with electronic fuel injection.
This engine with Honda’s fifth generation twin-spar aluminium frame, work seamlessly to deliver 450-class-leading power along with 250-style handling.
The CRF450R is an unprecedented blend of power, suspension and handling that together brought a genuine revolution to the motocross class.
- Engine: 449cc single-cylinder, 4-stroke, liquid-cooled
- Max. Power output: 50 HP @ 9,000 rpm
- Max. Torque: 46 Nm @ 7,000 rpm
- Gearbox: 5 speed
- Seat height: 955mm
- Weight: 110 kg
- Price: £2,000 – £3,500
Honda CRF450L - 2019 Model
The Honda CRF450L is already a road legal dual sport which saves a lot of hassle when converting to Supermoto.
Based on the awesome CRF450R motocross you can guarantee the pedigree is there from the outset.
With a large 2 gallon titanium fuel tank, Showa suspension, agile chassis, nimble handling and great power delivery ensures the CRF450L is equally at home on the street or dirt.
Honda built the CRF450L with performance at its core. But in addition the bike offers up comfort and versatility as well.
- Engine: 449cc single-cylinder, 4-stroke, liquid-cooled
- Max. Power output: 53 HP @ 9,000 rpm
- Max. Torque: 48 Nm @ 7,000 rpm
- Gearbox: 6 speed
- Seat height: 940mm
- Weight: 130 kg
- Price: £9,469
KTM 300 EXC TPI - 2020 Model
Although 4-stroke Supermotos are the most popular, there’s no reason why you can’t convert a 2-stroke. However, these tend to be all or nothing machines and aren’t ideal for cruising or commuting.
The TPI stands for transfer port injection. This technology makes premixing fuel and jetting carburettors a thing of the past.
This 2-stroke is fuel injected!
The 300 XCE TPI engine’s plethora of low-end torque enables you to easily ride a gear higher to maintain traction in slick areas. It has ample mid-range power all coupled in a lightweight chassis.
- Engine: 300cc single-cylinder, 2-stroke, liquid-cooled
- Max. Power output: 47 HP @ 8,500 rpm
- Max. Torque: 43 Nm @ 7,600 rpm
- Gearbox: 6 speed
- Seat height: 960mm
- Weight: 103 kg
- Price: £8,350
Final Thoughts
If you decide on a Supermoto conversion then always do plenty of research beforehand.
The are many Supermoto forums where you can share your ideas and get great advice. Whatever motorcycle you are converting it’s most likely been done before.
YouTube is also a fantastic platform for studying Supermoto conversions as… “a picture is worth a thousand words”.
Hopefully this page has proved useful and given you some ideas for your Supermoto conversion. 
