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KTM 85 SX: a youth motocross bike, wheel sizes and what to check
The KTM 85 SX is a family of 85 cm³ two-stroke motocross bikes designed for younger riders and competition. We look at how the two wheel sizes differ, who they're suited to, and what to check when buying used.
The 85 SX in brief
The 85 SX is KTM's youth motocross bike, aimed at kids and teens who have already gained some basic experience. It's not intended for road use — this is a competition and training bike, used on tracks.
The bike has been in production since 2003 and is one of the most popular 85 cm³ competition bikes in Europe.
Versions — how they differ
The main choice is wheel size. The 85 SX comes in 'small wheel' (smaller wheels, 17-inch front and 14-inch rear) and 'big wheel' (larger wheels, 19-inch front and 16-inch rear) versions. Smaller wheels suit shorter younger riders, while larger wheels are better for taller ones.
From earlier models to the latest, the frame, plastics, suspension, and brake control have all changed, so when choosing, it's worth looking at not just the year, but also the child's height and experience.
Engine and gearbox
The engine is an 85 cm³ two-stroke, liquid-cooled, single-cylinder unit. It delivers impressive power for such a small bike and has a rev-happy, thrilling character.
The gearbox is manual, the clutch is cable-operated, and power is transmitted via a chain. Like other two-strokes, it requires regular maintenance.
What to check when buying a used 85 SX
Most importantly — the engine's hours and service history: the piston rings, seals, and other parts need to be replaced regularly. Ask when the engine was last overhauled and if there are any receipts.
Check the frame, suspension, chain, sprockets, brake discs, wheel bearings, and plastics. Look out for signs of crashes and ensure the motorcycle's size is suitable for the child.
Trim levels
No specific trims; we provide general descriptions of the variants.
85 SX (maži ratai)
several generations17-inch wheels at the front and 14-inch at the rear.
- Suitable for shorter drivers
- Easier to handle
- Often — cheaper
85 SX (dideli ratai)
several generations19-inch wheels at the front and 16-inch at the rear.
- Suitable for taller drivers
- More stable at high speeds
- Often — more expensive
85 SX (varžybinis)
general descriptionOften additionally prepared for racing.
- Often — parts that need replacing
- Check the engine hours
- Check the paperwork
Comparing variants
| Maži ratai | Dideli ratai | Varžybinis | |
|---|---|---|---|
| Who it's for | For younger, budget-conscious drivers | For young professionals | For enthusiasts |
| Engine | 85 cm³, two-stroke | 85 cm³, two-stroke | 85 cm³, two-stroke |
| Wheels | 17 / 14 inch | 19 / 16 inch | Depending on the version |
| Price in the used market (relatively) | €€ | €€ | €€ |
The key is to choose based on the child's height: smaller kids need smaller wheels, taller ones need bigger ones. Before buying, check the engine's condition.
Pros
- Designed for youth motocross racing
- Two wheel sizes based on height
- Light and agile two-stroke engine
- Good availability of spare parts
Cons
- Requires frequent engine maintenance
- Not road-legal
- Condition of used motocross bikes varies greatly
Frequently asked questions
What age is the 85 SX suitable for?
Typically for teenagers and older kids with experience; the exact age depends on height and skills. Consult with a coach.
Can the 85 SX be ridden on the road?
No — it's a competition motocross bike without road equipment, designed for tracks.
How to choose wheel size?
Based on the child's height and experience: smaller kids need 17/14, taller ones need 19/16. Before buying, test if the child can comfortably reach the ground.
Updated 2026-10-21 · Trim levels and equipment vary by market and model year — check the equipment of the specific car. · Translated automatically
