New Zongshen RX3 (ZS250GY-3) Dual Sport

[rtking]

Originally Posted by SpudRider

It's official; the RX3 will have the 17-inch rear wheel with the cushion hub. I hope they offer a selection of larger rear sprockets, but one way or another, we will make it work.

Yay! Joe posted up on the CSC blog a bunch of good info. (http://californiascooterco.com/blog/?p=14427)

I posted this on another forum, but thought I'd include the summary from the CSC blog here:

1. 17" rear wheel is now standard (with cush hub)
2. 300 watt alternator will be standard (instead of the former 220 watt)
3. Swingarm is mounted via 4 needle bearings
4. Aluminum panniers and top case will be an available accessory
5. Engine rev limiter is 11,000 rpm, though redline is 9,000 rpm. (Does it make power up to 11K? And what's the rationale for a 9K redline?)
6. Each bike is dyno tested and must spin up to 91 mph minimum (94 mph observed)

Per Joe, the 17" rear wheel will result in a 2.6% reduction in gearing vs the 15" wheel and tire. (But CSC will have plenty of sprockets to tailor the power delivery to each rider's preference per the blog.) In my calculation, 2.6% variance can be offset by going with a 130/80-17 (4% taller than the 15" wheel setup), thus yielding an overall taller rear tire by 1.4%, but opening up a broader selection of rear tires.

Exciting news just in time for Christmas!

[SpudRider]

Indeed, that is a lot of good news from China.

However, I don't understand how a 17-inch rear tire can be smaller in diameter than a 15-inch rear tire. The stock, 15-inch rear tire is size 130/90-15. The 17-inch, Minsk rear tire is size 130/70-17. Despite the difference in diameter, both of these tires fit a 3-inch wide rim. The American equivalent of a size 130/70-17 tire is a size 5.10-17 tire.

The stock, 15-inch rear tire is a street tire, and all tires of size 130/90-15 are about 610-615 mm in diameter. Here are some examples of tires that size from the CST website.

http://www.csttires.com/int/moto/street-tires/c915/
http://www.csttires.com/int/moto/street-tires/c6502/
http://www.csttires.com/int/moto/street-tires/c6520/
http://www.csttires.com/int/moto/street-tires/c907/
http://www.csttires.com/int/moto/street-tires/c907y/

Now let's examine some 17-inch tires. The CST C6017 is also a street tire. The C6017 tire in size 130/70-17 is 640 mm in diameter.

http://www.csttires.com/int/moto/street-tires/c6017/

However, gaining access to knobby tires is the real reason to switch to a 17-inch rear tire, and even when they are the same size, knobby tires are larger in diameter than street tires.

Here are the diameters of a nice selection of 17-inch knobby tires which are available for sale in North America. All of these tires fit a 3-inch rim.

Shinko 244, size 5.10-17
Diameter: 25.63 inches, or 651 mm

http://www.shinkotireusa.com/tire/244-series



Shinko 700, size 5.10-17
Diameter: 25.63 inches, or 651 mm

http://www.shinkotireusa.com/tire/700-series



Kenda K270, Size 5.10-17
Diameter: 25.9 inches, or 658 mm

https://www.denniskirk.com/642024.sk...utm_medium=cse



Kenda K760, Size 130/90-17
Diameter: 26.3 inches, or 668 mm

http://www.kendatire.com/en/motorcyc...trakmaster-ii/



Therefore, I am glad to hear a variety of larger rear sprockets will be available.

Joe, can you tell us the sizes of the front and rear rims on the RX3 bikes being built for us? Also, can you tell us the stock number of teeth on both the counter shaft (C/S) sprocket, and the rear sprocket? Finally, what sizes are the larger rear sprockets which will be available?

Thank you for your interesting and informative reports from Chongqing.

[SpudRider]

If I were riding one of the Backcountry Discovery Routes, I would prefer to mount a Kenda K760 rear tire. If possible, I would also like to gear down the sprocket ratio for a little more torque.

[SpudRider]

[SpudRider]

If you are riding an off road adventure, you need a front tire which won't dump you in the mud. I like the CST, Surge I tire in size 100/90-18 for the front wheel of the RX3.

http://www.csttires.com/int/moto/off...c7210-surge-i/

http://www.bikebandit.com/tires-tube...-BWhoCHQnw_wcB

[SpudRider]

Please note, it was an orange RX3 which topped 95 mph (154 kph) on the dynamometer.

[SpudRider]

Every time I see that tail light, I like it better. The rear fender is also very nice, and should do an excellent job keeping the mud off the bike and rider.

[fishman10]

For real a 17'' rear wheel,,,,,,,it truly is christmas ,,,cause i was bummed about that from the beginning.

[jimjr21]

For those of us that like to do nice break in programs, that is out the window. The put the hammer down on these bikes with zero time.

I am really really really liking my Christmas present upgrades!

[Weldangrind]

Originally Posted by SpudRider

The fastest, orange bike even looks good sitting on the assembly line.

Man, I'm chomping at the bit on your behalf!

[Weldangrind]

Originally Posted by SpudRider

Also, the RX3 might lack some power at lower rpms because the stock sprocket ratio is geared a little too high.

Has there been any talk about what the countershaft sprocket design is? I wonder how easy it will be to find alternative sizes.

[Weldangrind]

Originally Posted by Wolftrax

The engine character of the RX3 is very similar to that of the WRX250R. The Yammy is a bit dodgy at lowere RPMs but loves to be flogged at higher revs. No surprise since both are 77x53.6 with a 11.5 compression ratio. This is going to be a kick ass motor.

No wonder it's liquid cooled! I hadn't picked up on the compression ratio of the RX-3.

[Weldangrind]

Originally Posted by Wolftrax

It's like high and low range like my old Suzy TC120.

I love the old TC / TS / TM bikes! I still have two TS bikes in the shop. Too bad the TS forum has been taken over by spam.

[/hijack]

[Weldangrind]

Originally Posted by SpudRider

I'm not worried about the counter shaft (C/S) sprocket. The C/S sprocket appears to be a readily available, Suzuki sprocket.

That answers my question.

[Weldangrind]

Originally Posted by SpudRider

Please note, it was an orange RX3 which topped 95 mph (154 kph) on the dynamometer.

That would certainly exceed my expectations for a 250!