Dong Fang DF 250 RTB Bobber Information

**barnone** · 09-04-2014, 09:25 PM

Originally Posted by booi10

Hi Please can anyone help ??? i have just purchased and received a DF Bobber here in the U.K. ,,, i have had to register it and it passed our tests easily ...... the only thing is the VIN plate says its a 125cc ??? but every were i look on the internet forums etc tells me these are 250cc ??? is mine restricted for the U.K roads and if so how can i de-restrict ??? and any one help with any good performance Mods ?? thanks i look forward to hearing from you ??? and by the way the bike looks awesome.....

booi10,
Welcome to the DF250RTB thread. The DF250RTB is actually 229cc. There is also a DF125RTB which is 125cc.

http://nbchariot.com/product_show.asp?id=674

I'm thinking that you have a 125cc engine which is a clone of a Honda CG125. If so then you might find a big bore kit. Not a simple de-restriction.

**culcune** · 09-05-2014, 01:10 AM

Post photos of the bike and try to get photos of the manufacturer plate of you new bobber, booi10. That should help you or some of us members answer questions you might have; there are people here who can decode VIN #'s for instance to find the original manufacturer since Chinese bikes are notorious for being sold under many, many different brands, sometimes within the same country even though they were made at the same OEM in China! My guess is since the UK and other countries in Europe start with learner-legal 125's, this is most likely a 125cc version.

**booi10** · 09-05-2014, 08:54 AM

IMG_3442.jpg IMG_3443.jpg IMG_3444.jpg IMG_3445.jpg IMG_3442.jpg IMG_3443.jpg IMG_3444.jpg IMG_3445.jpg
please see pictures ???

**booi10** · 09-05-2014, 09:05 AM

the pictures must have copied twice !! so this is the bike it had only 7 miles when I got it,,, its a 2012 model as the vin plate shows, im not small 17 stone and the bike pulls me well,, I just wanted to know if there were any mods really to help in that department,,, can I change the sprockets ?? I think I would rather have a better low end as going up hills is always gonna be a slow effort with a 125cc , thanks for you help so far guys...... barnone & Culcune

**barnone** · 09-05-2014, 11:58 AM

boo
Good looking bike.
First time I have seen the DF125RTB. Looks very similar to the DF250RTB. Like the rear fender support.

IMG_3442.jpg

IMG_3445.jpg

I'd ride her a bit before doing any modifications. 17 stones equals 238 lbs so you might need to help the seat spring a bit.

IMG_3443.jpg

IMG_3444.jpg

DF125RTB

**booi10** · 09-05-2014, 12:19 PM

thanks barone ..... or I could try loose a bit weight !!! haha its all muscle honest......... yes I have 250miles on the clock now and next job is to paint her orange.... so do you know the best sprocket lay for my earlier question ?? and how hard would it be to get a 250 engine in the bike ?? and how much are they (at a later date) .... just another quick how easy or hard are parts sourced for the bikes

**barnone** · 09-05-2014, 01:01 PM

Originally Posted by booi10

thanks barone ..... or I could try loose a bit weight !!! haha its all muscle honest......... yes I have 250miles on the clock now and next job is to paint her orange.... so do you know the best sprocket lay for my earlier question ?? and how hard would it be to get a 250 engine in the bike ?? and how much are they (at a later date) .... just another quick how easy or hard are parts sourced for the bikes

UK Ebay for parts such as rear sprockets. Does your DF125RTB have a 45 tooth rear sprocket? I'm running a 35 tooth rear at my 200 lbs but remember we have a bit more power with our 229 cc engine. JTR279.35
I am assuming that he DF125RTB has the same chain and rear sprocket as the DF250RTB. I could be wrong so you need to check.
http://www.ebay.co.uk/itm/JT-SPROCKE...item5afa4c6106

If you read through this thread you will find that we are not too happy with the performance of the 167FMM engine of the DF250RTB so I would not recommend an engine swap using the 229cc engine.
I'd try and find a 250cc overhead cam engine like this one off UK Ebay (http://www.ebay.co.uk/itm/250cc-Zong...item3a8f2a0a26)
but not from Australia because of the high shipping.
Look for one in the UK.$(KGrHqQOKiYE2qoF6(YlBN)3MYYWW!~~_12.JPG
Should be an easy swap but I HAVE NOT DONE IT so do some checking on your own.

**booi10** · 09-05-2014, 02:06 PM

barnone .... yes mine is 45 T ,,,, so how do you which one to choose if our make of bike is not listed ?? I take it the engine a such are a copy of something ?? I don't think it would be worth swapping the engine for 250 you would be better changing the bike or up to least 450cc,, thanks very much for help you sound very knowlagable and its the first time I have used a forum .... so happy days

**axa** · 09-05-2014, 02:17 PM

Originally Posted by booi10

barnone .... yes mine is 45 T ,,,, so how do you which one to choose if our make of bike is not listed ?? I take it the engine a such are a copy of something ?? I don't think it would be worth swapping the engine for 250 you would be better changing the bike or up to least 450cc,, thanks very much for help you sound very knowlagable and its the first time I have used a forum .... so happy days

all the JTR279.xx series have the proper spacing. you can go to their site, see the series and specs.
i have the 35 and 30 which im swapping in today.

i wouldn't know what the costs of getting an entirely new engine is in the UK, and i don't know the comparison in performance of the cg125 clones compared to the 250 clones, but if you can confirm the outer sleeve bore size, stroke length, and guegen pin diameter, you may will be able to drop a much less expensive 167fmm cylinder and head.
But again, i dont know what that would buy you in terms of a performance gain

I can tell you that you need to be quite mechanically inclined to do so, but its a possibility.

**axa** · 09-05-2014, 02:38 PM

That said... i finally broke in the new decked head 10.0 ratio engine and can definitively say this.
It is a more powerful engine than the stock one I had.
Note Ive said not a stock Loncin 167FMM but, the stock Loncin 167FFM that I had... That means, i can only compare it to my original that blew up after 1000 miles. Could there have been something wrong with it, I dont know, but it is possible. Something lead to its destruction where others have not, there are many variables.
Ive always suspected questionable springs because from all the ones i have now gone through, ive found their specs in pressure quite different, even within the same set... And also now i am running steel rods, not the aluminum stock ones so that's another factor.
But there might have been nothing wrong with it at all... it was seemingly performing as well (or poorly) as everyone had (excluding the dimension bending Gardo and Dan the 2 of course)

But here is the the test, on the long half mile say 8% grade hill i take everyday to work i would have trouble holding 50 indicated at times. Today, i took the entire hill at a steady ~57 indicated.
I dont put much stock into what my top end is, for one thing that will vary with the gear ratio and other conditions, also im breaking it in and not much willing to take it over 6k anymore... So i will be swapping in my 30 sprocket immediately and taking it from there.

Im still running a 110 jet as before, so i should tune with this new setup. I get ALOT of afterfire, and im missing my exhaust gasket which could aggravate that situation.

well see how this goes, but im quite pleased with the results.