There are very few sounds that can't be beaten. The crack of a soda can on a blistering hot day. The ping of the perfectly executed golf shot. And the scream of a 125 cc 2-stroke charging down a long straightaway. The 2025 KTM 125 SX takes its leads directly from the Factory Racing team and puts them to work like nothing else. Like the sound it makes, it cannot be beaten.
FROM £8,999.00
As always, the suspension boasts an easy tool-free setup at both ends, ensuring you chase down the podium in total control. On the rear, a hand-adjustable dual compression control allows riders to adjust high- and low-speed settings in a matter of seconds. The forks on the front end are also easily adjusted thanks to hand-adjustable clickers on the bottom of the fork shoe and top cap.
Pre-mix gets a remix across the 2-stroke KTM SX range, with Electronic Fuel Injection setting the standard. Now there's no more fiddly jetting setup pre-race, And thanks to the Keihin EFI and reed valve case design, you can be guaranteed of laying down optimal power at any altitude, all of the time.
With EFI comes great rideability. Along with the electronic fuel injection is an electronic power valve on the KTM 125 SX, allowing for more usable power throughout the rev range. Smoother power means better traction. Better traction means holeshot heaven!
Designed to churn out torque the 2025 KTM 125 SX is set to continue its dominance in its class with unrelenting forward momentum. With an overall engine weight of just 39.3 lb (17.86 kg) and impressive horsepower figures, this lightweight power-plant retains its typical high-revving character, while laying down the grunt where it matters most.
Once again slicing into the 125 cc class with the leading edge of technology, the 2025 KTM 125 SX features a map select switch allowing the racer to switch between 2 engine maps. The White Map - or Map 1 - provides a linear, predictable power delivery ideally suited to attack hard-packed dirt with a leaner air-fuel mixture. Alternatively, the Green Map - Mapping 2 - is tuned for loose, thick sandy conditions with a richer mix.
Get ready for a full-on berm assault. The 2025 KTM SX and SX-F machines have received major frame updates directly from Factory Racing efforts. For starters, the frame area around the rear shock mount has been updated and made more streamlined, with new engine mounts and cut-outs for improved chassis flex. The front area of the frame is also updated. with a different wall thickness than the previous model year, with renewed engine mounts. This adds up to a 300g weight saving and improved flex for better cornering.
Upgraded tank shrouds using bi-compound plastics channel air towards the radiators more efficiently, while a new fuel tank roll, makes for a tighter, more secure fitment, reducing the chance of frame scrubbing and dramatically improving durability. All this works alongside the specially-developed rider triangle, to provide unmatched knee contact and gripping surfaces - especially when standing on the pegs.
With a major emphasis placed on mass centralisation, the 2025 KTM 125 SX engine is designed to centralise rotating mass for optimal operation with the chassis. This results in a lighter, more agile handling feeling.
Let's get the technical parts out of the way first; the 48 mm WP XACT AER forks fitted to the 2025 KTM SX and SX-F line-up features a capsulated air spring and pressurised oil chamber for progressive and consistent damping, while oil and air bypasses reduce pressure peaks. In combination with the mid-valve damping system, all this provides exceptional feedback and rider comfort. The fork also boasts new settings, which not only compliment the updated frame and rear linkage, but ensures stellar performance at all levels. Speaking of settings, these are easily adjusted via a single air pressure pre-load valve, as well as easy-access click adjusters for compression and rebound. Additionally, the air pump needed to adjust the fork's air pressure is provided as standard in the buy-pack..
An upgraded rear brake pedal finds its way onto the 2025 KTM Motocross range, adding additional stiffness, bending resistance and braking feel to the overall package. At the other end, a forged steering head connection and CNC-milled triple clamps, make for the perfect alignment of the fork tubes. This precise geometry of the fork clamps ensures highly responsive and smooth fork action – not to mention unwavering stability when charging across ruts and onto the podium.
ENGINE | |
Transmission | 6-Speed |
Starter | Electric Starter |
Stroke | 54.5 mm |
Bore | 54 mm |
Clutch | Wet multi-disc DDS clutch, Brembo hydraulics |
Displacement | 124.8 cm³ |
EMS | Vitesco Technologies EMS |
Design | 1-cylinder, 2-stroke engine |
CHASSIS | |
Weight (Without fuel) | 92.4 KG |
Tank Capacity (Approx.) | 7.2L |
Front Brake Disc Diameter | 260 mm |
Rear Brake Disc Diameter | 220 mm |
Front Brake | Disc Brake |
Rear Brake | Disc Brake |
Chain | 520, Non-sealed |
Frame Design | Central double-cradle-type 25CrMo4 steel |
Front Suspension | WP XACT-USD (AER) Ø 48 mm |
Rear Suspension | WP XACT Monoshock with linkage |
Ground Clearance | 359 mm |
Seat Height | 958 mm |
Suspension Travel (Front) | 310 mm |
Suspension Travel (Rear) | 300 mm |
With KTM Finance, nothing stands in your way – you can now ride away on your own dream set of wheels. Our range of finance packages gives you the freedom to hop onto your READY TO RACE bike as early as tomorrow, as well as giving you the option to enhance your KTM even more with official KTM PowerParts.
The benefit of using these finance plans is that you can configure them yourself, making them flexible and tailored to you. You choose an installment amount that best fits your lifestyle and budget by adjusting your deposit or term, and you'll be in the seat before you know it. It's easy to customise the monthly amounts to suit your situation.
You enjoy flexibility with a variety of finance plans from KTM Finance. Want a new motorcycle? A few more performance-boosting KTM PowerParts? What about some extra items from the stylish KTM PowerWear range? No problem! With a range of finance plan from KTM, you'll get exactly what you need. It's flexible and personalised. KTM Finance offers you a full package that fulfills your every wish.
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Finance subject to status. Terms & Conditions apply. At the end of a PCP agreement there are 3 options: (I) Part exchange the vehicle, (ii) Pay the Optional Final Payment / Guaranteed Future Value to own the vehicle or (iii) Return the vehicle. Further charges may be made subject to the condition or mileage of the vehicle. Applicants must be 18 or over. Guarantee may be required. Santander Consumer Finance RH1 1SR.
*PCP available on Road registered models, with a guaranteed future value only.
OTR | £17,349.00 |
Customer Deposit | £5,399.00 |
Amount of Credit | £11,950.00 |
48 Monthly Payments of | £125.01 |
Optional Final Payment | £9,998.75 |
Total Amount Payable | £21,398.23 |
Total Charge for Credit | £4,049.23 |
APR Representative | 9.40% |
Duration of Agreement | 49 Months |
Annual Contracted Mileage | 4,000 |
Excess Mileage Charge | £0.149 |
OTR | £15,599.00 |
Customer Deposit | £195.00 |
Amount of Credit | £15,404.00 |
48 Monthly Payments of | £194.84 |
Optional Final Payment | £8,930.00 |
Total Amount Payable | £18,477.32 |
Total Charge for Credit | £2,878.32 |
APR Representative | 5.90% |
Duration of Agreement | 49 Months |
Annual Contracted Mileage | 4,000 |
Excess Mileage Charge | £0.149 |
OTR | £13,799.00 |
Customer Deposit | £4,100.00 |
Amount of Credit | £9,699.00 |
48 Monthly Payments of | £95.58 |
Optional Final Payment | £8,456.25 |
Total Amount Payable | £17,144.09 |
Total Charge for Credit | 3,345.09 |
APR Representative | 9.40% |
Duration of Agreement | 49 Months |
Annual Contracted Mileage | 4,000 |
Excess Mileage Charge | £0.149 (plus VAT) |
OTR | £15,999.00 |
Customer Deposit | £4,700.00 |
Amount of Credit | £11,299.00 |
48 Monthly Payments of | £135.41 |
Optional Final Payment | £8,456.25 |
Total Amount Payable | £19,655.93 |
Total Charge for Credit | 3,656.93 |
APR Representative | 9.40% |
Duration of Agreement | 49 Months |
Annual Contracted Mileage | 4,000 |
Excess Mileage Charge | £0.149 (plus VAT) |
OTR | £11,699.00 |
Customer Deposit | £158.00 |
Amount of Credit | £11,541.00 |
48 Monthly Payments of | £158.19 |
Optional Final Payment | £6,030.00 |
Total Amount Payable | £13,781.12 |
Total Charge for Credit | £2,082.12 |
APR Representative | 5.90% |
Duration of Agreement | 49 Months |
Annual Contracted Mileage | 4,000 |
Excess Mileage Charge | £0.149 (plus VAT) |