Quick Analysis
KTM 85 SX
22.5 pts
Unweighted: 13 advantages
EnginePerformanceDimensionsBrakesTyresOther
KTM 50 SX
4.5 pts
Unweighted: 4 advantages
EnginePerformanceDimensionsBrakesTyresOther
| Specification | ||
|---|---|---|
Engine Specifications |
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| Cooling System | Liquid cooling (0.8L) | — |
| Displacement | 84.9 cc | 49.9 cc |
| Engine Type | 1-cylinder, 2-stroke engine | 1-cylinder, 2-stroke engine |
| Power | 15.5 bhp @ 11500 rpm | 5.3 bhp @ 11500 rpm |
| Torque | 14 Nm @ 8500 rpm | 5.2 Nm @ 7500 rpm |
Performance & Efficiency |
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| Fuel Tank Capacity | 5.2 L | 2.3 L |
| Mileage | 25 kmpl | 30 kmpl |
Dimensions & Weight |
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| Kerb Weight | approx. 67 kg (without fuel) | 41 kg |
| Seat Height | 865 mm | 653 mm |
Brakes & Suspension |
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| Front Brake | Disc 240 mm | Disc 160 mm |
| Front Suspension | XACT 43 WP Upside-Down fork, Ø 43 mm | XACT 35 WP Upside-Down fork, Ø 35 mm |
| Rear Brake | Disc 220 mm | Disc 160 mm |
| Rear Suspension | XACT WP PDS mono shock | XACT WP mono shock |
Tyres & Wheels |
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| Front Tyre | 70/100 - 17 | 60/100 - 12 |
| Rear Tyre | 90/100 - 14 | 2.75 - 10 |
| Tyre Type | Tubed | Tubed |
| Wheel Type | Spoke | Spoke |
Other Specifications |
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| Color Options | Orange | Electronic Orange |
| Cons | Not road legal and suitable only for off-road tracks. High maintenance due to 2-stroke engine rebuilds. Kick-start only, no electric start option. Relatively expensive compared to other youth dirt bikes. Small fuel tank limits long riding sessions. | High Maintenance: As a 2-stroke engine, it requires frequent servicing and tuning. Small Fuel Tank: Limited capacity means more frequent refills. Kick-Start Only: No electric start, which can be tricky for very young riders. Limited Power for Older Kids: The 50cc engine may not be enough as the rider grows or becomes more skilled. Sensitive to Tuning: Owners report issues like fouling spark plugs or needing to frequently re-jet the carb: “Used to run great … then started fowling plugs … Moved to a 95 main jet … About 15 kph slower …” Parts Cost & Availability: As a race‑oriented bike, some parts can be expensive or harder to source for older models. |
| Detailed Overview | The KTM 85 SX is one of the most popular and respected youth motocross bikes in the world, designed specifically for young riders who are ready to take the next big step toward competitive racing. More than just a beginner’s off-road bike, the 85 SX brings true race-bred DNA from KTM’s full-size SX lineup, giving upcoming racers the opportunity to experience high-level performance at an early age. With its sharp power delivery, lightweight design, and premium components, the bike is built to help young riders improve skills and confidently tackle motocross tracks. At the heart of the KTM 85 SX lies its 84.9cc 2-stroke, liquid-cooled engine, which is known for delivering punchy power and rapid acceleration. The powervalve system ensures that the engine produces strong torque across the rev range, making the bike easier to control while still offering impressive performance. Whether riders are attacking tight corners or hitting long straights, the engine responds crisply and delivers the thrilling character 2-strokes are known for. Paired with a 6-speed gearbox, the bike offers smooth shifting and plenty of flexibility for both beginners and experienced youth racers. One of the standout features of the 85 SX is its lightweight chassis, made with high-strength chromoly steel. This frame not only enhances stability but also ensures precise handling, allowing riders to maneuver confidently through jumps, whoops, and rough terrain. The ergonomics are thoughtfully designed to fit young riders, offering a slim body that allows easy movement, better grip, and improved control during aggressive riding. Suspension is another area where KTM excels, and the 85 SX is no exception. It comes equipped with WP XACT suspension, featuring an AER air fork at the front and a fully adjustable shock absorber at the rear. This setup provides excellent damping, great response on jumps, and impressive support on uneven surfaces. Riders can also fine-tune the suspension to match their weight, riding style, and track conditions — something rarely seen in youth motocross bikes. The bike also features powerful disc brakes on both ends, giving young riders the confidence to brake hard into corners. The wave-style discs help with heat dissipation, which is especially important during long practice sessions or competitive races. Lightweight wheels, grippy motocross tyres, and a race-focused design further enhance the overall performance package. In terms of ergonomics, the KTM 85 SX is designed to feel like a miniature version of the bigger SX bikes. The seat height, handlebar position, and narrow bodywork all work together to provide comfort while promoting proper riding posture. This allows young riders to develop good habits early in their riding journey. Overall, the KTM 85 SX is a bike built for serious young racers who want real performance, durability, and race-ready features. With its responsive engine, excellent suspension, strong brakes, and lightweight build, it stands out as one of the top choices in the youth motocross segment. Whether used for training or competition, the 85 SX gives riders a true taste of professional motocross performance. | The KTM 50 SX is a purpose-built mini motocross bike, tailored primarily for very young and beginner racers who want to get a genuine motocross experience without jumping straight to bigger bikes. It’s more than just a “toy” — KTM has packed serious race-bike DNA into this 50cc model, making it a standout choice for youth motocross training and competitive racing. At the heart of the 50 SX is a 49.9 cc single-cylinder 2-stroke engine, which delivers a punchy yet manageable power output. According to KTM’s specs, this engine is paired with a centrifugal automatic clutch, meaning there’s no manual clutch lever to worry about — the clutch engages automatically, which is ideal for young riders still building coordination and confidence. The engine uses a Seletra 2p D36 system for fuel delivery (on some models), which helps in precise tuning and reliable performance. KTM has thoughtfully designed the chassis for both strength and agility. The frame is made from chromoly steel, which keeps it light but sturdy. The overall design ensures that the bike is highly maneuverable, making it easier for young riders to learn balance and control on a real race-ready structure. The 50 SX isn’t just about motor and frame — it comes with serious suspension too: a WP XACT 35 mm upside-down fork at the front and a WP mono‑shock at the rear.The front suspension travel is around 200 mm and the rear is close to 190 mm, giving enough give for track bumps and jumps. In terms of ergonomics, the seat height is just 653 mm, making it very accessible for younger riders. Ground clearance is around 233 mm, giving the bike enough space to handle uneven terrain without scraping too much.The fuel tank capacity is modest — 2.3 liters — but that’s more than enough for short motocross sessions that young riders typically do. For braking, KTM hasn’t compromised: the 50 SX is equipped with disc brakes both front and rear, each 160 mm in size. This provides good stopping power and control, which is very important for safety and learning advanced braking techniques. On the wheels front, the bike uses spoke wheels, keeping things light and rugged for off-road racing. Despite its small size, the 50 SX is very race-focused. The frame has been redesigned to mimic the flex and rigidity characteristics of full-size MX bikes. The new frame also comes with frame protectors, which help reduce damage in case of falls — a common occurrence when young riders are learning. The handlebars are lightweight aluminum, with a bend that suits smaller riders, and the footpegs are designed to give a solid grip even when things get muddy or rough. KTM also includes power-reduction kits in its parts catalog for the 50 SX. These kits let parents or coaches limit the power output while the rider is still learning, which is a smart way to scale the bike’s performance to the rider’s ability — and once they’re better, the full power can be unlocked. When it comes to reliability, the 50 SX has a liquid cooling system for better thermal management. The engine’s central crankshaft design helps in keeping the mass well-balanced, which contributes to smoother handling. As for maintenance, like all 2-stroke motorcycles, it does need regular care — but KTM has made key parts (like the clutch) durable, using a reinforced clutch basket for longevity. Overall, the KTM 50 SX is a very well-engineered youth motocross bike that brings real race performance to younger riders. It balances power, weight, and control in a way that helps beginners grow into serious racers. Whether for track training, competitive racing, or just building early riding skills, it’s absolutely one of the top choices in the mini-moto world. |
| Expert Review | MotoAutiv Team | MotoAutiv Team |
| FAQ (Manual Override) | Q: What is the mileage? A: The mileage is around 18–20 kmpl (may vary as it’s an off-road motocross bike). Q: What is the engine capacity? A: The KTM 85 SX comes with an 84.9 cc 2-stroke engine. Q: What is the seat height? A: The seat height is approximately 850 mm. Q: What is the top speed? A: The top speed is around 110 km/h, depending on rider and terrain. Q: Does the KTM 85 SX have electric start? A: No, it comes with a kick-start mechanism. Q: What is the fuel tank capacity? A: The fuel tank capacity is 5.2 liters. Q: Is the KTM 85 SX road legal? A: No, it is not road legal as it is designed specifically for motocross/off-road racing. Q: What type of brakes does it have? A: It features disc brakes at both front and rear. Q: Is the KTM 85 SX suitable for beginners? A: It is ideal for youth riders transitioning to higher-powered bikes, but not recommended for complete beginners. Q: What is the weight of the bike? A: The bike weighs approximately 68 kg (dry weight). | Q: What is the engine capacity of the KTM 50 SX? A: It has a 49.9 cc 2-stroke engine. Q: What kind of transmission does it use? A: The KTM 50 SX has a single-speed automatic transmission. Q: How is the KTM 50 SX started? A: It uses a kick-start. Q: Does it have a clutch? A: Yes — a centrifugal (adjustable) clutch, so the rider doesn’t have to use a manual clutch lever. Q: What is the fuel tank capacity? A: The fuel tank capacity is 2.3 litres. Q: What is the seat height? A: The seat height is 653 mm. Q: What is the weight of the bike? A: The dry (or “without fuel”) weight is about 43.5 kg for recent models. Q: What kind of suspension does the KTM 50 SX use? A: It comes with WP XACT suspension — a 35 mm upside-down fork in the front and a WP mono-shock at the rear. Q: What brakes does it have? A: It has disc brakes both at the front and rear, each 160 mm. Q: What power does the KTM 50 SX produce? A: The KTM 50 SX produces around 5.3–5.4 PS at ~11,500 rpm. Q: Is the KTM 50 SX road legal? A: No — it's designed for off-road / motocross use, not for street-legal riding. Q: What kind of clutch does it have for young riders? A: It uses a centrifugal clutch, which automatically engages at high RPM — good for beginners or young riders who don’t manually operate a clutch. Q: What is the ground clearance? A: The ground clearance is 233 mm. Q: Is there a guarantee or warranty for KTM 50 SX? A: According to specs, it has a 2-year standard warranty. Q: What is the typical maintenance challenge or issue to watch for? A: Some owners report carburetor tuning issues |
| Price Variants | | 669000 | | 475000 |
| Pros | Powerful 2-stroke engine with strong mid-range performance. Lightweight chassis for excellent handling on tracks. Premium WP suspension for smooth jumps and rough terrain. Strong disc brakes offering sharp stopping power. Race-ready ergonomics designed for young motocross riders. | Very Lightweight: Makes it easy for young riders to handle and build confidence. Automatic Transmission: The centrifugal clutch and automatic gearbox simplify riding for beginners. Adjustable Suspension: High-quality WP fork and shock can be tuned to rider weight and track conditions. Racing‑Oriented Build: Frame and components are derived from KTM’s full-size SX range, giving a race-ready feel. Power-Reduction Kits Available: Helps beginners by limiting power until they’re ready for more. Good Cooling: Liquid cooling ensures the engine stays healthy even under hard off‑road use. Tool-Free Adjustability: Seat height, suspension, and other parts can be adjusted without special tools. |
| Starter | Kickstarter | — |
| Transmission | 6 Speed Manual | Manual |
