Forums 🚥 PiT STOP 🔧 Hyosung Technical Help 520 upgrade for gv125s question – Chain & Sprocket Kit Reply To: 520 upgrade for gv125s question – Chain & Sprocket Kit

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North UK


Send us an email (tap here) and we can do you an X-RING deal for the GV125-S EFi bike. The 520 chains do not fit OEM sprockets as they are bigger and thicker in general so the sprockets you have will need changing.

IMO, the 428s are standard for most 125cc bikes  (except bikes like KTM Duke etc , use 520 factory chains) but the 428s can’t beat the longevity of a 520.   Hence we never sell 428s on this site as it means more cost for customer  (you swap more 428 kits than you do a 520)

Plus contact us to customize your gearing for you ,  want acceleration ? (only ride around 30-40mph all day) or you ride at 70mph all day on dual carriage ways  , or just a balanced kit , either way , you will pull better that’s for sure.  Sorry if this sounded like an agressive push towards you leaning to a 520

If sticking with OEM parts, Hyosung uses 138 links on their 428s on 125cc twin models   (sometimes 132-136) .   Your local garage that supplies any 428 chain, will usually have a 150L chain and he will cut links as appropriate to service a customer machine  (if unsure of the bike’s original link count)

I know that an X-RING is the best grade 520 there but an HD520 is what we commonly send & they do a good job over the 428s.
– Rear sprocket = 2yrs (unlimited miles  or until the chain says it needs replacing)
– Front Sprocket = naturally this will wear out a bit sooner than rear because its smaller that’s all.

If I missed something ,  just let me know!

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