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Home > Products > Rear Sprocket > RST > SUPERSPROX STEALTH REAR SPROCKET RST-990:42-ORG


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Product Extra Information

Material Aluminum Center/Steel Teeth
Chain 520
Teeth 42
Color ORG
Inner diameter (ID) 125
Pitch circle diameter (PCD) 150
Bolt hole 8.5
Type RST
Product Application
ModelFrom yearTo Year
125 EGS19921999
125 Enduro19861990
125 Enduro19911994
125 Enduro19861987
125 Enduro19881988
125 Enduro19891989
125 Enduro19901990
125 EXC19912003
125 EXC20042010
125 EXC19982005
125 EXC20062010
125 EXC20042011
125 EXC20122017
125 EXC & ENDURO19891997
125 EXC Six Days20122016
125 SX19952021
125 TC20142021
125 TC20202021
125 TE20162021
125 TE20142016
125 TX20172021
125 XC-W20172021
125 XC-W TPI20202021
144 SX20072008
150 EXC TPI20202021
150 SX20082014
150 SX20152021
150 TE i20202021
150 XC20102016
150 XC20102015
150 XC20102021
200 EXC19992005
200 EXC20062011
200 EXC20122016
200 EXC20122016
200 MXC19992004
200 SX20032006
200 XC20062009
200 XC-W20062016
250 EC20202021
250 EGS19901999
250 EXC19962004
250 EXC20122021
250 EXC Enduro19911994
250 EXC Enduro19951995
250 EXC Enduro19962004
250 EXC Enduro20052005
250 EXC Enduro20062011
250 EXC Enduro20122021
250 EXC Racing20022002
250 EXC Racing20022010
250 EXC Racing20062006
250 EXC Six Days20122021
250 EXC Six Days20102011
250 EXC Six Days20122013
250 EXC TPI20182021
250 EXC-F Enduro20072011
250 EXC-F Enduro20122013
250 EXC-F Enduro20142021
250 EXC-F Six Days20102011
250 EXC-F Six Days20122013
250 EXC-F Six Days20142021
250 FC20142021
250 FE20162021
250 FE20142021
250 MXC19982002
250 SX19962003
250 SX20042016
250 SX20172021
250 SX-F Factory Edition20172021
250 SX, SX-F20042016
250 SX, SX-F20172021
250 TCi Motocross20142021
250 TCi Motocross20162016
250 TCi Motocross20172021
250 TE20112014
250 TE20142021
250 TE I 2-Stroke20182021
250 XC Enduro20062007
250 XC Enduro20082021
250 XC-F20122016
250 XC-F Enduro20062011
250 XC-F Enduro20122021
250 XC-W Enduro20102018
250 XC-W TPI20182018
250 XC-W TPI20192021
250 XCF-W Enduro20072011
250 XCF-W Enduro20122016
250 XCF-W Six Days20112014
250 XCW-E20082009
300 EC20202021
300 EXC Enduro19901997
300 EXC Enduro19981998
300 EXC Enduro19991999
300 EXC Enduro20002004
300 EXC Enduro20052005
300 EXC Enduro20062011
300 EXC Enduro20122017
300 EXC Six Days20102011
300 EXC Six Days20122021
300 EXC TPI Enduro20182021
300 EXC TPI Erzberg Edition20202021
300 MXC20032005
300 MXC20162016
300 SX19931995
300 TE20112014
300 TE20142021
300 TE i20182021
300 TE I Jarvis Edition20202021
300 TX20142021
300 XC-W Six Days TPI20192021
300 XC-W TPI20192021
350 EXC-F20122021
350 EXC-F20142021
350 FC20142021
350 FC20142015
350 FC20162017
350 FC20182021
350 FC2022021
350 FE20132013
350 FE20142021
350 FE (S - USA)20142021
350 FX20172021
350 TE20142021
350 XC-F20132021
350 XCF-W20132016
350 XCF-W Six Days20142016
350 XCF-W/Six Days20142016
360 EXC19961997
360 SX19961997
380 EXC19982002
380 SX19982002
390 FE Enduro20102012
400 EXC-F Factory Edition20102011
400 EXC-G RACING20062006
400 EXC, EXC Racing20002005
400 FC 4 Speed20002001
400 FC 6 Speed20002001
400 FE e20002003
400 LC4 enduro19931996
400 LSE & LC4 enduro19972001
400 SX19992002
440 SX19941994
450 EXC R20162016
450 EXC Racing20032011
450 EXC Racing & 450 XC-G Racing20072012
450 EXC-F20172021
450 EXC-F20132015
450 EXC-F20162016
450 EXC-F Factory Edition20102011
450 EXC-F, EXC-F Six Days20172021
450 EXC, EXC Six Days20102012
450 EXC, EXC Six Days20142016
450 FC20042006
450 FC20142021
450 FC20142015
450 FC20162021
450 FC20202021
450 FE20142021
450 FE20142015
450 FE20162016
450 FE20172021
450 FE Enduro20092014
450 FE-e20042008
450 FR Rally20162016
450 FS20162021
450 FS-e Supermoto20042008
450 FX20172021
450 FX20172021
450 FX Cross Country20102012
450 MXC Racing20052005
450 Rally Factory Replica20152021
450 SMR20042007
450 SMR20082014
450 SMR20042007
450 SMR20082014
450 SX20032003
450 SX F20072012
450 SX F20132015
450 SX F20162021
450 SX F Factory Edition20172021
450 XC F20082009
450 XC-F20082009
450 XC-F20132021
450 XC-W20122016
450 XC-W20072009
470 FC20012001
500 EXC20142016
500 EXC20142021
500 EXC-F20172021
500 XC-W20122016
501 FC20002001
501 FE20142015
501 FE/S20162021
505 SX F20072009
505 XC-F20082009
520 EXC20002002
520 SX19992002
525 EXC20032005
525 MXC20052005
525 SMR20042005
525 SX20032006
530 EXC R20082011
530 EXC, EXC Six Days20102011
530 XC-W (R)20082009
530 XC-W Six Days20102011
550 FC20032004
550 FC20052006
550 FE-e20042008
550 MXC, DX, DXC19931996
560 SMR20062007
560 SMR20062007
570 FE20092012
570 FS20102011
600 LC4 enduro19911993
600 LC4 MX19901992
620 EGS/E Adventure19981998
620 LC4 Duke19951998
620 LC4 enduro19901998
620 LC4 SX19951998
620 LSE19971998
625 LC4 SC20022002
625 SMC20052006
625 SXC20032006
640 Duke & 640 LC4 (SM)19972006
640 LC4 ENDURO20002005
640 LC4 ENDURO Adventure R19992007
640 LC4 SUPERMOTO19992006
650 FE-e20032008
650 FS-e/FS-c20032008
660 SMC20032004
660 SMC20052006
690 Duke R20082021
690 Enduro R20192021
690 Enduro, Enduro R20082018
690 SMC R20122021
690 SMC/R20082016
690 Supermoto20072010
701 Enduro20162016
701 Enduro20172021
701 Enduro LR20202021
701 Supermoto20152021
790 Adventure/ 790 Adventure R20172021
790 Duke20172021
890 Duke R20202021
All Models (Except R30)19952004
Svartpilen 70120182021
Vitpilen 70120182021

Select option below to choose diffent teeth and color

Out of stock

Each order from 220PLN value of goods, indlude free shipping inside Poland. If order total is less then 220PLN, shipping cost will be calculated.


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Product Description Image

Available in colors


Check your bike model for availabe color. More color options in Custom sprocket Section

Category Description

Why Supersprox Stealth

  • Upgrade your motorcycle drive system and extend chain system wear life
  • Specifically designed for street and off-road use
  • Durable steel teeth, can be expected to last 3 times longer than an aluminum sprocket
  • The only sprocket in the world with Tri-Zink electro plating, 100% eliminating dangerous abrasive oxidation
  • Aluminum core reduces rotational mass, allowing faster acceleration
  • Only Supersprox forged stainess steel rivet technology, has been proven by world champions in motorcycle racing



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FAQ: Frequently asked questions

Products FAQs

Return policy

Unused items in saleable condition purchased from our eShop may be returned within 30 days of the purchase date for a credit to the card on which they were originally purchased. Returned goods will only be accepted with prior authorization. For more detailed return policy click here.

I received a damaged product

If the sprocket you purchased is damaged please make images and send to us by email and one of our representative will connect with you within 48h.


Exchange of the sprocket is possible only if the sprocket is not used and purchased from our eshop directly. Return sprocket will be fully refunded (excluding shipping) and a new order for the exchange sprocket has to be placed on our eshop.


All sprockets are guaranteed against defects in material and workmanship. Because we cannot control the application of our sprockets, buyers assume risks for any and all damage caused to themselves and others due to any failures. No warranty, expressed or implied, is made. Sprockets are designed and manufactured to be used specifically on the models listed in our catalog. Clearances must be checked before ordering different size sprockets than originally came on the machine. Chains are guaranteed in accordance with the manufacturer’s own terms of warranty. All products leave our warehouses in good condition, therefore if you receive an item that is not in good condition it should be immediately reported.

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    Shipping methods

    Each order from 220PLN value of goods, indlude free shipping inside Poland. If order total is less then 220PLN, shipping cost will be calculated.

    Gear Ratio


    Gear ratio explained. The gear ratio, is the ratio of turns made by one gear, compared to the other gear, when the gears are connected by a chain. An example of gear ratio will be with one gear of 10 teeth and the second gear of 20 teeth, giving a ratio of 2 (20/10=2). To calculate the ratio, devide the number of teeth on the rear sprocket, by the number of teeth on the front sprocket and the resulting number is your gear ratio.
    Why do you need to know your gear ratio? It might be, that your bike is not performing as you would like and a change in gear ratio might help the performance.
    GEAR DOWN. An example of this would be, that the bike is difficult to start in first gear and the clutch needs to be used more than you would like. You have plenty of top end speed, but need more slow speed control. The answer, might be to GEAR DOWN the bike. You can do this by adding more teeth to the rear sprocket or reducing the number of teeth on the front sprocket.
    GEAR UP. The opposite situation, might be that the bike has lots of power, but is reaching the rev limiter in top gear and you would like to reduce the revolutions at a particular speed. To do this, you would need to GEAR UP the bike. By reducing the number of teeth on the rear sprocket or increase the number of teeth on the front sprocket.
    Diameter of gear. Each tooth added or taken away from a sprocket, will reduce the diameter of the sprocket by a given amount. For simplicity, you can think about 5mm change on the diameter, for each additional or reduced tooth. This will help understanding in relation to space requirements for gear ratio changes.
    Chain length. The addition of teeth to the sprocket, may require a longer chain or changing the position of the rear wheel, by moving that backwards or forwards. It will depend on the addition or subtraction of sprocket teeth. This can be calculated by considering the chain pitch. For simplicity, you can think about each chain link requiring 16mm length (actually 520, 525, 530 chains require 15.875mm per link to be exact). But the chain is going around the rear sprocket and the front sprocket, so the important number would be the change in diameter of the sprocket and not the chain length. An example would be to remove one tooth from the rear sprocket. This would make the chain more loose and to correctly adjust the chain, you would need to move the rear wheel backwards (away from the small sprocket) by 5mm. This movement would compensate for the change in diameter. Due to chain construction, it is not possible to remove only one link and it is necessary to remove even numbers of links (2, 4, 6, 8 etc).

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    Custom Product Teeth