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2021 KTM 85 SX [Model Overview]

2021 KTM 85 SX
KTM 85 SX Review Summary
Review Summary
Reader Rating19 Votes

The 2021 KTM 85 SX: The Competitive Edge In Junior Motocross

The 2021 KTM 85 SX is the final step in Junior Motocross, and to provide the best chances at a win, KTM makes two versions of the bike for the 2021 lineup. Both are powered by the same 85cc two-stroke single, producing over 20 HP, with the only difference between the two being wheel sizes. For the shorter rider, the 85 SX 17/14 gives a 17 inch front wheel, with a 14 inch rear. The 85 SX 19/16 similarly gives the taller rider a 19 inch front wheel and a 16 inch rear.

This Austrian-made bike is equipped much more like a fully-fledged supercross bike than a motocrosser, but it will still be competitive in both categories. A full 6-speed manual transmission is tuned specifically to get the power to the dirt, and also delivers a slightly more tame powerband once into the middle revs for long distance cross country racing. WP XAct suspension is once again the suspension of choice.

KTM’s designers have also not only given the 85 SX series a 6-speed transmission but have also included a wet, multi-disc hydraulic clutch, designed by FORMULA racing. This is a race-grade product and lets the junior rider get an excellent feel for the bite point and lightning fast gear changes.

The 2021 KTM 85 SX 17/14 starts at $6,099 USD / $6,899 CAD, while the 85 SX 19/16 starts at $6,299 USD / $7,099 CAD.

On this page: we’ve curated specs, features, news, photos/videos, etc. so you can read up on the new 2021 KTM 85 SX in one place.

2021 KTM 85 SX

Model Overview

General Info

  • Price: $6,099 USD / $6,899 CAD
  • Key Features:
    • 6-speed manual transmission
    • WP XAct racing suspension included
    • Kickstarter only, no electric start

Main Specs

  • Engine Type: 85cc two-stroke single
  • Horsepower: Over 20 HP
  • Torque: Not provided by manufacturer
  • Wet Weight: 150 lbs (approx 68 kg)
  • Seat Height: 34 to 35 inches (865mm to 890mm)

2021 KTM 85 SX

2021 KTM 85 SX Specifications

From KTM


Engine 85cc , 1-cylinder, 2-stroke engine
Power Over 20 HP
Bore x Stroke 47 mm x 48.5 mm
EMS MEDJ digital
Power in KW
Starter Kickstarter


Clutch Wet, multi-disc clutch, Formula hydraulics
Transmission 6-Speed
Chain 1/2 x 5/16″


Suspension Front XACT 43 WP Upside-Down fork, Ø 43 mm
Suspension Rear WP Xplor PDS shock absorber
Brakes Front 240 mm,Disc brake
Brakes Rear 220 mm, Disc brake
Suspension travel (front) 278 mm
Suspension travel (rear) 305 mm
Tank capacity (approx.) 5.2 l
Color Black, Orange


Spark Plugs
Headlight LED
Tail Light LED


Overall Length
Overall Width
Overall Height
Ground Clearance 336 mm
Seat Height 865 mm
Wet Weight 67 kg



2021 KTM 85 SX

2021 KTM 85 SX Features


It took extreme levels of ingenuity to fit the race-winning formula of KTM’s bigger 2-strokes into a compact 85 cc engine. A special manufacturing process is used and provides impressive weight savings without sacrificing strength or durability. The super compact power plant is fitted with a 6-speed gear box and delivers class-leading power and rideability throughout the entire rev range. The power valve plays a key role in tailoring power delivery to suit track conditions and rider ability, ensuring that the only rider surprised by the incredible performance is the competition.


The cylinder on the KTM 85 SX has a bore and stroke of 47/48.95 mm. It features a sophisticated power valve system, which controls both the exhaust valve and the sub exhaust ports, giving the bike excellent torque and power delivery. This translates into significant midrange performance, reducing the need to overwork the clutch in loamy or sandy conditions. An adjuster screw allows the opening time of the power valve to be adjusted to suit rider preference and track conditions.


The KTM 85 SX features a strong and reliable clutch with an extremely compact design. The clutch is easily actuated by the FORMULA hydraulic system, which conveniently ensures that play is always compensated for, keeping the clutch “bite” point the same throughout the ride and under all conditions.

Crankcases and engine covers

The crankcases are manufactured using a high pressure die-cast production process, keeping wall thickness to a minimum while retaining strength and durability. The design of the cases is very compact and aims at positioning the shaft arrangements as close as possible to the center of gravity, contributing to better handling.


The 85 SX features a light and robust 6-speed gearbox. The gear ratios have been developed to perfectly match the characteristics of the engine, while easy and precise shifting allows the rider to select the next gear quickly and confidently. The gearbox features a new drive shaft which uses a screw for front sprocket fixation and diaphragm spring instead of a circlip, ensuring secure front sprocket fixation. Another highlight of the 85 SX transmission is the “no-dirt” gear shifter. Similar to the footpeg design, it prevents the build-up of dirt and ensures the next gear is always available, no matter what the conditions.


The frame on the KTM 85 SX is a scaled-down version of the championship-proven full-size frames. It is professionally crafted using hydroformed chromium molybdenum steel tubes that are robot welded, ensuring the highest levels of consistent quality. The flex characteristics have been specifically tailored for easy handling and optimal comfort, while working in perfect harmony with the suspension, to ensure excellent agility and high-speed stability. For 2020, the frames feature highly durable orange powder coating and come with standard frame protectors.


Made from lightweight aluminum, the subframe provides rear fender stability and strong support for the rider at little extra weight.


The KTM 85 SX has “no-dirt” footpegs, which have a simple but effective self-cleaning system that ensures the footpegs return to their original position, providing complete control in all conditions.


The KTM 85 SX features a strong, lightweight, tapered aluminum handlebar, with a specifically shaped bend to suit the overall ergonomics. Additionally, the bike comes standard with ODI lock-on grips, which include a vulcanized grip on the right side and a lock-on grip on the left that does not require glue or wire for mounting.

2021 KTM 85 SX Photos

2021 KTM 85 SX Videos


KTM Websites