Qingqi QM200GY / Qlink XF200 alternative sprockets
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 :icon10:
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
Gear ratios Suzuki DR200SE
The manual I've got covers models from 1997-2007.
The primary reduction and gear ratios have remained the same all those years, but the final reduction has changed slightly.
Here they are:
Primary reduction... 3.157
1st gear............... 3.000
2nd..................... 1.933
3rd...................... 1.437
4th...................... 1.095
5th...................... 0.913
The final reduction ratios are quoted as:
Years 1997 to 2003 and 2007 as 3.000 (15/45)
For 2004, 2005 and 2006 it was 3.916 (12/47)
I assume the figures in brackets are the sprocket sizes?.
Would be nice to be able to fit DR200 sprockets, but I seem to remember someone here (volksjagger?) saying something about how the countershaft on the Qingqi was too short to accomodate 520 sprockets. I can't see the Chinese making a special countershaft, just so they can fit a 428 chain set...