Reply To: Hello from USA.
Its okay ,
If you haven’t , you can get a good quality japan (any brand based in Japan) X Ring chain , start with 120 links then cut to fit, it lasts as long as you maintain it, we dont have an exact figure as its hard to keep track of everyone’s mileage as they all use varying qualities of the chain.
Rear sprocket, a fresh one is a good idea and always replace the front, the front sprocket being too worn down will eventually damage the shaft, and if you do replace the “Locking Tab” washer (i can’t stress this part enough) – If the lock tab washer was to rattle even slightly or be slightly worn on its splines, the nut will shoot out of the sprocket cover and watch the front sprocket make a hole in the engine. Seen it all in the UK where riders beg for replacement rare engines. better safe than sorry is to replace everything and torque well.
Use this tutorial as a guide
[How to Tutorial] Upgrade 520 chain & sprocket kit on GV125-S EFi (GV125 S 2019+ Models)
ignore that it is its smaller 125cc sister using a custom chain conversion but the principal is the same.
Riding to 10,000 rpm all day is the safe limit. I would not go any higher. If you don’t care about acceleration and use the freeways, then use a 15T (PBR in USA should be making them , i am not sure , as i just use my own local supply chain)
If its made in CHINA , DO NOT bother installing the sprocket, you will loose the engine! – Japan, Thailand (JT) (Some small Hondas are made in Thailand), EU, USA only.
Motul C2 lube is my Go to chain lube! Or use Scottoiler if you want something sophisticated (check youtube for any bike using it)