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Cobra CX50 JR
Factory Specifications
Clutch Oil235 to 350 cc
Clutch Oil300 cc (10 oz)
Pilot / Main Jet55 / 92
Fork Oil200 ml
Fork Oil145 ml
Fork Oil140 ml
Final Drive13 / 37 or 14 / 38
Final Drive14 / 37
Chain420 x 88
Chain420 x 100
Chain420 x 88
Spark Plug Gap0.023 to 0.025 in
Engine
| Engine type | 2-stroke, single cylinder, reed valve |
|---|---|
| Displacement | 49.8 cc |
| Bore and stroke | 39 mm x 41.7 mm, V head 2010 |
| Bore and stroke | 39 mm x 41.7 mm 2011-2026 |
| Cooling system | Liquid-cooled |
| Coolant | 50/50 antifreeze-coolant and distilled water 2010-2015 |
| Coolant | Liquid Performance Mini Coolant 2016 |
| Coolant | Bel-Ray Moto Chill 2017-2022 |
| Coolant | VP Racing Stay Frosty Race-Ready Coolant 2023-2026 |
| Fuel type | High octane pump gasoline 2010-2022 |
| Fuel type | VP Racing C50 2023 |
| Fuel type | High octane pump gasoline or VP Racing C50 2024-2026 |
| Premix oil type | Motul 800 2T Off Road 2010-2012 |
| Premix oil type | Bel-Ray H1-R 2013-2020 |
| Premix oil type | Spectro Premium SX2 2021-2022 |
| Premix oil type | VP Racing Premix Oil 2023 |
| Premix oil type | VP Racing X2 1050 2024-2026 |
| Premix ratio | 50:1 to 63:1 2010-2012 |
| Premix ratio | 40:1 to 50:1 2013-2017 |
| Premix ratio | 32:1 to 60:1 2018-2026 |
Fuel and ignition
| Carburetion | 14 mm Dell’Orto |
|---|---|
| Pilot / main jet | 55 / 92 |
| Needle | W7-2 2017-2026 |
| Float height | 16 mm + 0.5 mm |
| Ignition system | Electronic, analogic advance |
| Spark plug | Champion 8339-1, 8332-1 hotter, 8904-1 colder 2010-2011 |
| Spark plug | Autolite XS61 and 4261 2012-2018 |
| Spark plug | Autolite XS61, Champion RN6YC and 8339 2019-2023 |
| Spark plug | NGK BPR8ES or BRR8EIX iridium 2024-2026 |
| Spark plug gap | 0.023 to 0.025 in |
| Ignition timing | 0.040 in (1.0 mm) BTDC 2010 |
| Ignition timing | 0.035 in (0.9 mm) BTDC 2011-2013 |
| Ignition timing | 0.040 in (1.0 mm) BTDC 2014-2026 |
Drivetrain
| Transmission speed | Single speed, Cobra 3 shoe centrifugal clutch |
|---|---|
| Final drive ratio | 13 / 37 or 14 / 38 2010-2013 |
| Final drive ratio | 14 / 37 2014-2026 |
| Chain | 420 x 88 links 2010 |
| Chain | 420 x 100 links 2011-2014 |
| Chain | 420 x 88 links 2015-2026 |
| Clutch oil type | Cobra Venom 3 Shoe Clutch Milk (MCMUGF32) |
| Clutch oil quantity | 235 to 350 cc (8 to 12 oz) 2010-2016 |
| Clutch oil quantity | 300 cc (10 oz) 2017-2026 |
Chassis, suspension and brakes
| Front fork | Marzocchi 32mm 2010 |
|---|---|
| Front fork | Cobra 30mm USD 2011-2013 |
| Front fork | CARD 32mm USD Fully Adjustable w/ Smart Leg 2014-2026 |
| Fork oil type | SAE 20 weight 2010-2012 |
| Fork oil type | SAE 2.5 weight 2013 |
| Fork oil type | 2.5wt Bel-Ray 2014-2020 |
| Fork oil type | 5wt Spectro 2021-2023 |
| Fork oil type | 5wt 2024-2026 |
| Fork oil amount | 200 ml oil change, 220 ml rebuild 2010 |
| Fork oil amount | 145 ml 2014-2016 |
| Fork oil amount | 140 ml 2017-2026 |
| Fork std settings | Smart Leg 3 out, compression and rebound 1.5 out 2014-2026 |
| Rear shock settings | Compression low 7 clicks, high 7 clicks, no rebound adjuster 2013-2026 |
| Front tire | 2.50-10 2010-2014 |
| Front tire | 80/100-10 (2.75-10) 2015-2026 |
| Front tire pressure | 15 psi minimum |
| Rear tire | 2.75-10 2010-2014 |
| Rear tire | 80/100-10 (2.75-10) 2015-2026 |
| Rear tire pressure | 15 psi minimum, 20 psi hard pack or rocky |
Dimensions
| Wheelbase | 35.75 in (908 mm) 2010-2024 |
|---|---|
| Wheelbase | 36 in (914 mm) 2025-2026 |
| Wheel size | 10 in (254 mm) front and rear |
| Seat height | 23.9 in (607 mm) |
| Fuel tank volume | 0.65 gallon (2530 cc) 2024-2026 |
Torque specifications
Torque coverage grows with the model year. The 2010 to 2015 factory manuals published no brake fastener torques, and cylinder nut torque first appears in 2017. If a fastener you need is not listed for your year, call 877-632-1313 before you guess.
Engine
| Fastener | Nm | ft-lb | in-lb | Thread and locker |
|---|---|---|---|---|
| Cylinder nuts 2017-2026 | 30 | 22 | 265 | M8 x 1.0** |
| Cylinder head nuts 2010-2011 | 12 | 8.8 | 105 | M6 x 1.0 |
| Cylinder head nuts 2012-2016 | 14 | 10.3 | 123 | M7 x 1.0 |
| Cylinder head nuts 2017-2026 | 12 | 9 | 110 | M6 x 1.0 |
| Crankcase bolts 2010-2016 | 12 | 8.8 | 105 | M6 x 1.0 |
| Spark plug | See note | – | – | Hand tight, then 1/8 to 1/4 turn |
| Intake manifold bolts 2010-2017 | 6.2 | 4.6 | 55 | M6 x 1.0 |
| Intake manifold bolts 2018-2026 | 6.2 | 4.6 | 55 | M6 x 1.0, Loctite 243 |
| Water pump impeller 2011-2014 | 5 | 3.6 | 44 | M5 x 0.8, Loctite 263 |
| Water pump impeller 2015-2017 | 5 | 3.6 | 44 | M5 x 0.8, Loctite 243 |
| Water pump impeller 2018-2026 | 4 | 3 | 36 | M5 x 0.8, Loctite 263 |
| Engine mount bolts | 30 | 22 | 265 | M8 x 1.25 |
** Use a crow’s foot attachment oriented 90 degrees to the torque wrench. Cobra Moto factory manual footnote.
Clutch and ignition
| Fastener | Nm | ft-lb | in-lb | Thread and locker |
|---|---|---|---|---|
| Clutch nut | 54 | 40 | 480 | M10 x 1.25, Loctite 263 |
| Clutch bolts 2010 | 16 | 12 | 144 | M6 x 1.0 |
| Clutch bolts 2011-2026 | 16 | 12 | 144 | M6 x 1.0, Loctite 263 |
| Clutch cover bolts | 7.9 | 5.8 | 70 | M6 x 1.0 |
| CFD nut 2010 | 75 | 55 | 664 | 1/2 in x 20 left hand |
| CFD nut 2011 | 75 | 55 | 664 | 1/2 in x 20 left hand, Loctite 263 |
| Stator bolts 2010 | 2.8 | 2.1 | 25 | M5 x 0.8 |
| Stator bolts 2011-2026 | 2.8 | 2.1 | 25 | M5 x 0.8, Loctite 243 |
| Stator cover bolts | 2.3 | 1.7 | 20 | M4 x 0.75 |
| Ignition rotor nut 2010 | 54 | 40 | 480 | M10 x 1.25, Loctite 263 |
| Ignition rotor nut 2011-2013 | 45 | 33 | 400 | M10 x 1.25, Loctite 263 |
| Ignition rotor nut 2014-2026 | 45 | 33 | 400 | M10 x 1.25, Loctite 243 |
Stator bolts are 25 in-lb. Use an inch-pound wrench, not a foot-pound wrench. A foot-pound wrench will strip the case.
Chassis and suspension
| Fastener | Nm | ft-lb | in-lb | Thread and locker |
|---|---|---|---|---|
| Shock bolt | 47 | 35 | 420 | M10 x 1.5, Loctite 243 |
| Swingarm pivot | 28 | 21 | 250 | M14 x 2.0 |
| Triple clamp bolts (bottom) 2014-2017 | 8 | 6 | 72 | M6 x 1.0 |
| Triple clamp bolts (bottom) 2018 | 7 | 5 | 62 | M6 x 1.0 |
| Triple clamp bolts (bottom) 2019-2026 | 8 | 6 | 72 | M6 x 1.0 |
| Triple clamp bolts (top) 2011-2017 | 16 | 12 | 144 | M8 x 1.25 |
| Triple clamp bolts (top) 2018 | 12 | 9 | 108 | M6 x 1.0 |
| Triple clamp bolts (top) 2019-2026 | 10 | 8 | 90 | M8 x 1.25 |
| Steering stem pinch bolt 2019-2026 | 13 | 9.5 | 115 | M8 x 1.25 |
| Fork guard aluminum bolts 2019-2026 | 8 | 6 | 88 | Moly lube M6 x 1.0 aluminum |
Wheels and drive
| Fastener | Nm | ft-lb | in-lb | Thread and locker |
|---|---|---|---|---|
| Axle nuts, front and rear 2010-2017 | 34 | 25 | 300 | M12 x 1.25 |
| Front axle aluminum bolt 2018-2024 | 25 | 18 | 221 | M10 x 1.25, Loctite 243 |
| Front axle aluminum bolt 2025-2026 | 12-15 | 9-11 | 106-132 | M10 x 1.25, Loctite 243 |
| Front axle pinch bolts 2018-2026 | 10 | 7.5 | 88 | M6 x 1.0 |
| Rear axle nuts 2018 | 34 | 25 | 300 | M12 x 1.25 |
| Rear axle nuts 2019-2026 | 28 | 21 | 250 | M12 x 1.25 |
| Rear sprocket bolts 2010-2014 | 24 | 18 | 216 | M7 x 1.0, Loctite 243 |
| Rear sprocket bolts 2015-2017 | 22 | 16 | 195 | M7 x 1.0, Loctite 243 |
| Rear sprocket bolts 2018 | 28 | 21 | 250 | M7 x 1.0, Loctite 243 |
| Rear sprocket bolts 2019-2026 | 28 | 21 | 250 | M7 x 1.0 |
Brakes
| Fastener | Nm | ft-lb | in-lb | Thread and locker |
|---|---|---|---|---|
| Brake caliper bolts 2018-2026 | 12 | 9 | 106 | M6 x 1.0, Loctite 243 |
| Brake caliper to carrier 2018-2026 | 9.5 | 7 | 84 | M6 x 1.0, Loctite 243 |
| Brake pad secure 2018-2026 | 4 | 3 | 35 | M5 x 0.8 |
| Brake rotor bolts 2018-2026 | 12 | 9 | 108 | M5 x 0.8, Loctite 243 |
| Rear brake rotor bolts 2016-2017 | 12 | 9 | 108 | M6 x 1.0, Loctite 243 |
Gearing ratios
Front / rear teeth and the resulting ratio. A higher ratio number means lower gearing.
Taller gearing
More top speed. Hard pack and fast tracks
| 15 / 34 | 2.27 |
|---|---|
| 15 / 35 | 2.33 |
| 15 / 36 | 2.40 |
| 14 / 34 | 2.43 |
| 15 / 37 | 2.47 |
| 14 / 35 | 2.50 |
| 15 / 38 | 2.53 |
| 14 / 36 | 2.57 |
| 15 / 39 | 2.60 |
Middle range
Includes 14 / 37, factory gearing from 2014
| 13 / 34 | 2.62 |
|---|---|
| 14 / 37 | 2.64 |
| 15 / 40 | 2.67 |
| 13 / 35 | 2.69 |
| 14 / 38 | 2.71 |
| 15 / 41 | 2.73 |
| 13 / 36 | 2.77 |
| 14 / 39 | 2.79 |
| 15 / 42 | 2.80 |
Lower gearing
More acceleration. Sand, mud, hills, tight tracks
| 13 / 37 | 2.85 |
|---|---|
| 14 / 40 | 2.86 |
| 13 / 38 | 2.92 |
| 14 / 41 | 2.93 |
| 13 / 39 | 3.00 |
| 14 / 42 | 3.00 |
| 13 / 40 | 3.08 |
| 13 / 41 | 3.15 |
| 13 / 42 | 3.23 |
Do not gear too tall. On a centrifugal clutch the clutch slips instead of driving, which overheats it and shortens the life of seals, bearings and electronics.
What Changed on the CX50 JR by Model Year
Cobra revised this specification in forty-five documented places between 2010 and 2026. Select a year above to filter the whole page to it.
2011
- Chain to 420 x 100 linksUp from 420 x 88 links
- V head dropped from the bore and stroke specBore and stroke unchanged at 39 mm x 41.7 mm
- Front fork to Cobra 30mm USDReplaces the Marzocchi 32mm
- Ignition timing to 0.035 inDown from 0.040 in
- Ignition rotor nut to 45 NmDown from 54 Nm
- Loctite called out on clutch, stator and CFD fastenersTorque values unchanged
2012
- Spark plug to Autolite XS61 and 4261Replaces the Champion list
- Head nut torque to 14 Nm on M7Up from 12 Nm on M6
2013
- Fork oil to SAE 2.5 weightDown from SAE 20 weight
- Premix to Bel-Ray H1-R at 40:1 to 50:1From Motul at 50:1 to 63:1
- Rear shock settings publishedCompression low 7, high 7, no rebound adjuster
2014
- Front fork to CARD 32mm USD with Smart LegReplaces the Cobra 30mm USD
- Fork oil to 145 mlDown from 200 ml
- Final drive settles at 14 / 37Was 13 / 37 or 14 / 38
- Ignition timing back to 0.040 inUp from 0.035 in
2015
- Chain back to 420 x 88 linksDown from 420 x 100 links
- Water pump impeller locker to Loctite 243Was high strength 263
- Rear sprocket bolts to 22 NmDown from 24 Nm
- Tire sizes restated80/100-10 front and rear
2016
- Coolant to Liquid Performance Mini CoolantFrom 50/50 antifreeze and distilled water
2017
- Clutch oil to 300 ccReplaces the 235 to 350 cc range
- Head nut torque to 12 NmCorrected from 14 Nm, back to M6
- Cylinder nuts specified at 30 NmM8 x 1.0, first published this year
- Coolant to Bel-Ray Moto ChillFrom Liquid Performance Mini Coolant
- W7-2 needle documentedFirst published needle spec
- Fork oil to 140 mlDown from 145 ml
2018
- Premix range to 32:1 to 60:1From 40:1 to 50:1
- Front axle becomes an aluminum bolt at 25 NmReplaces the 34 Nm steel axle nut
- Rear sprocket bolts to 28 NmUp from 22 Nm
- Water pump impeller to 4 NmDown from 5 Nm, and to Loctite 263
- Loctite 243 added to the intake manifold boltsTorque unchanged at 6.2 Nm
- Disc brakes documentedCaliper, carrier, pads and rotor torques published
2019
- Rear axle nuts to 28 NmDown from 34 Nm
- Top triple clamp bolt to M8 at 10 NmWas M6 at 12 Nm
- Spark plug list adds Champion RN6YC and 8339Alongside Autolite XS61
2021
- Premix oil to Spectro Premium SX2From Bel-Ray H1-R
- Fork oil to 5wt SpectroFrom 2.5wt Bel-Ray
2023
- Coolant to VP Racing Stay FrostyFrom Bel-Ray Moto Chill
- Premix oil to VP RacingFrom Spectro Premium SX2
2024
- Premix oil to VP Racing X2 1050Specific grade named
- Spark plug to NGK BPR8ES or BRR8EIXReplaces the Autolite and Champion list
- Fuel tank volume published0.65 gallon, 2530 cc
- Fork oil listed as 5wt with no brandAny 5 weight fork oil is acceptable
2025
- Wheelbase to 36 inUp from 35.75 in
- Front axle bolt to 12-15 NmDown from 25 Nm
Cobra CX50 JR Service Procedures
Step by step procedures from the factory manuals, in readable form.
Break-in procedureComing soonStarting procedureComing soonMaintenance scheduleComing soonPre-ride inspectionComing soonTransmission and clutch oil changeComing soonAir filter cleaningComing soonChain adjustmentComing soonRear brake pedal heightComing soonFork air bleedingComing soonFork oil replacementComing soonSetting sagComing soonCFD check and adjustmentComing soonClutch service and inspectionComing soonCompression testingComing soonBase gasket selectionComing soonSquish measurementComing soonTop end disassembly and assemblyComing soonIgnition timingComing soonCooling system serviceComing soonCarburetor cleaningComing soonJetting for conditionsComing soonTroubleshooting by symptomComing soon
Cobra CX50 JR Factory Manuals
The complete service manual for each model year, as published by Cobra Moto.
2026 CX50 JR Service ManualOpen2025 CX50 JR Service ManualOpen2024 CX50 JR Service ManualOpen2023 CX50 JR Service ManualOpen2022 CX50 JR Service ManualOpen2021 CX50 JR Service ManualOpen2020 CX50 JR Service ManualOpen2019 CX50 JR Service ManualOpen2018 CX50 JR Service ManualOpen2017 CX50 JR Service ManualOpen2016 CX50 JR Service ManualOpen2015 CX50 JR Service ManualOpen2014 CX50 JR Service ManualOpen2013 CX50 JR Service ManualOpen2012 CX50 JR Service ManualOpen2011 CX50 JR Service ManualOpen2010 CX50 JR Service ManualOpen
Cobra Parts and Technical FAQs
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Every part on this page, matched to your exact model year and cross-referenced against the factory parts manual.
Sources. Every model year from 2010 to 2026, verified against Cobra Moto factory service manuals and technical service bulletins. Cobra Moto Parts is an authorized Cobra Moto dealer.