520 upgrade – Chain & Sprocket Kit Discussion for GV125-S Gv125 S EFi 2022

Hello,

No need to cut the chain,  we will do it for you.

Hyosung went from 140 links to 138 to 136 , so it meant some “early” models had slightly longer chain adjusters on the swingarm.

Your 22 plate will be fine! Email us if you have other sales enquiries, it will be quicker since it concerns the shop parts.

Sorry for the delayed reply.   Long day!

Vab wrote:

Thank you, Marcel. It’s only been a few hours, don’t apologise. Order was made today around 2pm gmt to Bradford, BD4 Thanks again!

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Bare with me for 3 days  (By wednesday i should be shipping it) because I need to order again the special rear sprocket   (There is only 1 company abroad that makes it for us so far), a customer took our last stock we had on the shelf today funny enough. So I will need more sprockets!

Hold tight, any “tracking alerts” will be sent to your email.

Any chance you could send us an email with your registration and VIN plate , i will know if hyosung made “hidden” change to the swingarm again because I made sure it is the same chain we sent to other lads last week, no issues fitting.

If you are very sure the adjusters are maxed out, then cut 1 link.  I really need to keep a long list of every customer bike that has a GV-S EFi and ask Hyosung why they keep changing factory chain sizes on the sly. It’s frustrating for me as a seller lol.    Good job on the fitting though!

You could Amazon Prime 1 Day a chain “breaker” to take 1 link out or a local garage can do it if its a short walk ?|

BEFORE cutting , sit on the bike and check chain slack , should be around 30-40mm pushed up from middle of chain.  (It can’t be tight when sitting!)

As long as you followed the tutorial , you should not have issues.   Remember the “HUMP” side of the front sprocket that has numbers written on it must be facing YOU  , then put the LOCKING washer on it.

“Rubber” on the old sprocket is just vibration damper , not needed as since the 428s rattle like skittles when shot up!

The “Holes” for screws on the sprocket means it fits a Yamaha bike.   You have a hyosung which uses a BIG nut and a locking washer.

Make sure washer is folded twice and tightly hugging the nut, if you do 80+ on that 520 chain, you don’t want that nut big rattling loose!  “medium loctite” also helps as an extra measure to lock thread.  “red loctite (high strength) is even better and torque the nut to 60 ft lbs (google FT LBS to NM conversion if your torque-wench says NM instead of FT.LBS)   this is to avoid you stripping the threads by being too tight!

Pictures of the VIN & Registration = send an email now (click contact at the bottom of this site), and I will respond, after responding  you will have our email to forward pictures.     Just need to keep your bike’s ID tags private from a public forum.

But yes we also want fitted pictures , i will use them on the Customer Shop Gallery page of the 520 kit 🙂

Chain Cutting = It is safer to use a “chain breaker” , since you need to remove one link and make sure the master link is safe to clip on again.  (Don’t rivet the master link, as the master link is a “Clip-On” type, so don’t damage the little “fish hook” that locks it.

Again, before cutting chain, sit on the bike and ensure the tension is good ,   (about 20mm movement is OK) and make your shocks stiffer  (pot hole country!) , that should make the chain less bouncy and saggy which would stretch it in the long run causing premature wear.

If you take a picture of your ECU , under the seat , i will confirm if it was an “early 2018-2019” model that was late registered.   (Some dealers buy the bikes and they stay in showrooms for years until the owner buys it and they give it a 24 plate for example unless it was “pre-registered” as soon as it landed in the country)

Rear Sprocket = Counter Sunk bolts used by Hyosung as they made 2 hubs (strange if you ask me) ,  your counter sunk bolts will be better used on the 520 and it will lock the 520 sprocket just fine.     (hence the counter-sunk bolt will sink in , as you screw in, until the 520 stops it. That means its locked enough, it will not rattle.)

If you see any rust , go to halfords and get Stainless Counter Sunk bolts for the rear sprocket as the back wheel gets a lot of dirt thrown at it!

Yup, that’s Hyosung!  – They use either a “stud and nut” with lock tabs  OR  as you witnessed on yours  , “Full Concave/Countersunk Torx” bolt.

Just as they made very slight changes to how long the chain adjusters are   (eg. 140 on early models vs 138 link OEM chain used on later models),  and hence I no longer supply bolts for the rear sprocket as it depends what hyosung chooses to do with their hubs!   –  Rear sprocket not an issue ,  just as long the original bolts are used or replace to stainless for the same ones.

Have a good weekend!