Qingqi QM200GY / Qlink XF200 alternative sprockets

[forchetto]

My bike comes with 134 links of 428 chain and sprockets 15 / 48 tooth.

These bikes can benefit from a raised overall gear ratio to lower rpm's at reasonable highway cruising speeds, 44 tooth for the rear sprocket seems to be a preferred size to achieve this.

If we could get a larger 16 tooth engine sprocket it would be about the same gear ratio change and would reduce the amount of chain wear. The smaller the front sprocket the greater the wear rate. In transmission engineering circles it's reckoned that if your application requires a long life, conventional wisdom says don't use a small sprocket with less than 18 teeth. However, I have seen karts with 10 or even 9 teeth on the small sprocket. Most of these guys have to put new sprockets on every race...

We can't get these 16 tooth sprockets easily, and the housing design won't allow for a greater size to be fitted, so it's the rear sprocket for us:

Here are some alternative sprockets from a Suzuki TS125ER that will fit. The part numbers given are the original (OEM) Suzuki numbers, so we can walk in a Suzuki dealership and ask for the correct item without suffering the shame and embarrasment of saying we have a Chinese bike

64511-48730----428 chain----42 teeth
64511-48700----428 chain----44 teeth
64511-48720----428 chain----45 teeth

If you have a spare half hour, this is a wonderful site dealing with bike transmission issues:
http://faq.f650.com/FAQs/SprocketsOtherSizesFAQ.htm

In fact the whole site, dealing mainly with BMW's F650 is a powerhouse of knowledge and wisdom. Very extensive though.
http://faq.f650.com/main.html