Dong Fang DF 250 RTB Bobber Information

**barnone** · 03-11-2011, 02:21 AM

Originally Posted by chucksplace

heres my bikeAttachment 3372please help

That's a different bike that I know nothing about. Have you read this thread? Here is the bike we are discussing here.

It's a DF250RTB. Sorry but there is no need for me to call you.
I got my bike from a different but screwed up outfit.

**bighabeeb** · 03-11-2011, 02:40 AM

Originally Posted by chucksplace

heres my bikeAttachment 3372please help

Meh redacted. Not worth it :p

**Aboshi** · 03-11-2011, 03:15 AM

word you need to relax lol.
These things take time to get to you after ordering...
Figure 10-15 days to get to you're door from the time they ship it out, then tack on another 3-5 days for the MSO at the very least.
I placed my order from countyimports and it says the order is completed but still not tracking #, and that was 3 days ago (I placed the order about 6 days ago). I'm not sweating it and I'm sure they will ship it out when they can. So just sit back relax and start getting ready for when you're bike arrives.
Also have they charged you're credit card yet?
If you don't have that bike in your hands in 3+ weeks after your order and they charged you're card just do a charge back and order it from somewhere else.

**Gardo** · 03-11-2011, 06:19 AM

Originally Posted by chucksplace

heres my bikeAttachment 3372please help

Ahh the DF250cha Nice looking 3/4 chopper. OK Chuck here's my take. Relax take a breath From what I read on this chopper its got the Same engine as the DF250RTB and similar frame. Now I bought from Scooterdepot their Customer Service sucks but the get the job done. Remember they are in CA which is 3hrs behind the East Coast when you call expect to be on hold for 20+ minutes. The folks are nice and will try to help, if wotask for a manager.

I found calling them at 4pm EST/ 1pm PST is the best time. Be cool Barnone and I Posted Pics of the bikes. And our exp with the different comp that we dealt with.
As far as the shipping is concerned I also had to take a day from work I freight companies have the hours that they do business, just the way it is.

oh from ordering the bike to getting my MSO took 15 days

**Aboshi** · 03-11-2011, 06:13 PM

So I have been playing with the gear ratios and the sprocket setup that I'll wind up going.
Here are the exact ratios for these motors.
you can get the speed calculations here http://www.bikerenews.com/Stories_Ar...Calculator.htm
Also I believe these are the sprockets we need, but thats only if it is a 520 chain: http://www.jtsprockets.com/52.0.html...el_uid=4657&p=

Just plug in all of this info:

Max RPM: 8000
Tire Size: 140/70/18
Primary Drive Ratio: 3.333
Final Drive Ratio: 13/45 (I will have a 13/35)
1st Gear Ratio: 2.9.9/1
2st Gear Ratio: 1.867/1
3rd Gear Ratio: 1.389/1
4th Gear Ratio: 1.150/1
5th Gear Ratio: 0.9545/1

With this ratio top speed in 5th gear at 8000 rpm should be 53 mph. (the manual says max hp 11Kw @6500RPM)
I figure it will more likely be 78-81 mph (this doesn't seem right at all from what all the dealers claim a top speed of 75mph).
Also I don't see these motors sustaining 8000 rpm for long periods of time so figure you'll be cursing at around 5500-6500 rpm.

**barnone** · 03-11-2011, 08:06 PM

Aboshi,
Good information on the sprockets and gearing.
So with a 13/40 71MPH at 8k RPM stock
So with a 14/40 77MPH at 8k RPM
So with a 14/38 81MPH at 8k RPM
So with a 13/35 82MPH at 8k RPM
Thanks

**ChinaV** · 03-12-2011, 01:32 AM

I don't understand how those speed calculators work if they don't take into account the size of the chain and sprockets. A 428 chain and sprocket setup running 13/40 is not the same as a 520 / 525 / 530 setup running 13/40. Seems to me there's a calculation factor missing ???

Cheers!
ChinaV

**Aboshi** · 03-12-2011, 03:16 AM

Its generalized, it doesn't matter the chain or motor size. It is usually pretty accurate though.

**barnone** · 03-12-2011, 05:01 AM

Originally Posted by ChinaV

I don't understand how those speed calculators work if they don't take into account the size of the chain and sprockets. A 428 chain and sprocket setup running 13/40 is not the same as a 520 / 525 / 530 setup running 13/40. Seems to me there's a calculation factor missing ???

Cheers!
ChinaV

ChinaV,
I don't know why they would not be the same ratio. What does the size of the chain have to do with it?
40/13=3.08
The 13 tooth sprocket has to turn 3.08 times to get the 40 tooth sprocket to turn one time.

**jape** · 03-12-2011, 05:25 AM

It is worth a bit of thought. Confuses me too though because I forgot all my tech school science! So ... one turn of the sprocket with a certain size tyre will travel a certain distance, I can see that. So where does power come into it? Just faster acceleration and carry more weight? But bigger engines don't usually rev any more than small. And if power applied does have anything to do with it the width of chain and sprocket would make a difference, so would width of tyre. Ah damn, now I've got a headache!