Premium 520 Chain Sprocket Kit – Hyosung GT125R GT125 GT250
Stop the stretch and eliminate sluggish final drive lag for good. The stock 428 on the 125cc models is severely overworked on a heavy 180kg machine, making a premium final drive overhaul the safest way to gain crisper performance and long-distance durability during your next maintenance project. The 250cc models will just get a better chain that lasts longer than original Korea ones!
- Optimised Gearing // Specifically ratioed sprocket configurations wake up your torque curve to deliver better zip without over-stressing internal valves. (A little acceleration boost while still hitting 80+ mph – Good for hills or quick sprints!)
- Premium Chains // Supplied exclusively with genuine Japanese or European link lines from premier brands like RK, EK, DID, DC, or JT. .
- Bonus Pack Additions // Arrives completely loaded with free stainless steel rear sprocket bolts and a new front sprocket lock washer.
- In Stock // Ready for your final drive system maintenance work. Bring heavy-duty 600cc-grade strength directly to your rear wheel assemblies.
Description
The 125cc and 250cc sports models are built on a full “Big Bike” frame structure. Weighing nearly 180kg, they are far heavier than a standard lightweight commuter bike, meaning using a standard 428 pitch chain setup is a severe mechanical weak spot. Moving your bike up to this premium 520 chain conversion bundle introduces larger rollers and thicker side plates used natively by 600cc machines. While the heavier link links expand surface area to distribute engine load forces better, our optimised internal gearing more than compensates for the rotating mass. Owners report a straightforward swapout that eliminates the constant stretch of cheap original equipment, making your bike drive much smoother with better 0-60 zip and a punchier engine rev range across your latest restoration project.
💎 TRANSMISSION OVERHAUL CONVERSION SPECIFICATIONS
| Component | Details |
| Heavy Duty 520 Chain | Premium black or dark grey link line sourced from RK, DID, EK, or JT.
(Need a GOLD chain? Contact us directly). |
| Precision Cogs & Bolts | High-durability front and rear steel sprockets paired with unrustable stainless rear sprocket bolts to replace weathered factory fasteners cleanly. |
| Front Lock Washer | Essential safety lock tab piece included inside the box to secure proper engine front sprocket nut retention. |
📜 Confirmed Model Fitment
Hyosung Models: Fits the following models below only, providing an immediate performance upgrade for both carburettor and fuel injection layouts. See the diagram picture for sprocket spacing metrics.
| GT125 Naked Comet / GT125P / GT125R / RC All models up to 2021 (Noticeable acceleration zip) |
GT250 Naked Comet / GT250R / RC All production years (Massive longevity jump over OEM Korea ones) |
🔧 Installation Tips
Overhauling final drive components requires solid workbench alignment to maximize your mileage. Follow these pointers from the community:
- Maintain Perfect Rear Hub Alignment: When pulling your axle back into place, verify that your left and right swingarm marks track identically. Misalignment creates sideways chain wear and unbalances torque flow.
- Apply Thread Locking Fluid to Bolts: Use a drop of medium thread-locker on your rear sprocket mounting screws to protect the assembly from hard V-twin motor vibration lines.
- Observe the 20mm-30mm Slack Parameter: Always leave roughly 20mm-30mm of free play slack in the center of the link lines when the machine is resting on its wheels to avoid binding your gearbox bearings.
Additional information
| Weight | 3 kg |
|---|---|
| Dimensions | 30 × 30 × 4 cm |
14 reviews for Premium 520 Chain Sprocket Kit – Hyosung GT125R GT125 GT250
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GARAGE PICKS // ADD TO BUILD
-
Anodized Short Gear Shift Bar [Shifter Linkage Rod] – GT125 Naked & GT250 Comet Hyosung
£21.00 -
Anodized Gear Shift Linkage Rod [Shifter Bar] – GTR 125 250 RC Hyosung
£19.99 -
Front Engine Sprocket Nut – Hyosung GV125 GT250 GT125R GV250 RT125D
£12.99 -
SwingArm Spool Kit {Race Stand Bobbins Sliders} – Hyosung GT125 GT250 GT125R GT250R
£34.99
EXPLORE // RELATED PRODUCTS
Independent Shop supplying ride enhancements and quality spares with fast dispatch. Need assistance? Access our workshop guides, manuals, tutorials or drop by the forums for troubleshooting help.
shane –
Made a improvement to my 125 got abit more top end aswell
Mick –
Fantastic pieces of kit cheers marcel they work a treat
Jason –
Once again amazing service and delivery they look good too
Daryn –
Instant gains from this kit amazing worth every penny
Lee Bartlett –
Fantastic service from marcel.
Brilliant bit of kit and would recommend anyone looking to upgrade to buy this kit.
Jake Carter –
Fast delivery and straightforward fitment
Andy Elias –
Easy to fit and instant gain, quick service too. cheers Marcel
Matt –
Bought a couple of weeks ago and finally fitted last week. Made a good improvement to gearing and acceleration.
Jed –
Bought to replace my 428 set. Big improvement in gearing and it’s lots smoother now! Bigger sprockets, chunkier chain = better looks. Really happy with the purchase, thanks Marcel!
Andy –
Easy simple fit.
Kevin Barrier –
Straight swap, easy fit. Looks great. Will post pictures later. Bigger front and rear sockets, longer thicker chain. I am perfectly happy with my purchase and hand delivered by Marcel. Excellent product, great store. Will be using again
Owen –
Definitely worth it, Bike now drives much smoother, gearing is way better. I would highly recommend to switch to this kit
dufferdave –
Much better quality than oe items, fitted perfectly, much smoother and performance gains noticeable instantly, well worth the money. thanks Marcel.
Stu –
Bought for 2016 GT. Straight forward swap out. Bike feels better geared in all gears. No massive top end gains but worth it for the increased rideability!!