Dong Fang DF 250 RTB Bobber Information

Hello everyone,
First of all, I like to thank everyone for all the great info. The info provided by ya has fixed some of the problems i had. Thank you guys. I bought my 2012 DF250 RTB-A from Killer Motorsports at the end of June and received the DF in the middle of July. Since then, I have not received my papers to register the DF. I regret buying from Killer Motorsport as they customer service sucks a$$.
Anyways, my problem with the DF is that I can't seem to get pass 55mp without the engine sputtering or choking, or it seem as it is cutting out.
When I first got the DF, it felt as the riding was heavy and it picked speed slow. But after reading this great forum, I adjusted the valve on the crank and the DF became better. The valves had no gap what so ever.
Here is a list of mods I have done to my DF:
- close out the secondary air system ( as it kept busting the hose)
- change the stock swear sprocket to a 35 tooth
- added a 108 main jet, and the mechanic did something to the pilot jet where it acts as a 45 pilot jet
- added 3 washers to the needle jet
- tried a reverse air ram with the new filter I bought on eBay. ( I will post that air filter pic soon) the reverse air ram didn't work as I was going 35-40 mph the engine would just die out. Put the stock filter back on and the engine did a lot of sputtering around 40 mph. So, I tried this other filter I ordered on eBay that looked similar to our stock air filter except it has a plate cover on top of the air filter. That filter resulted a smoother ride till the problem I'm having around 55 mph.
- changed all turn signals to led, along with a new led halo headlight
Is anybody having trouble at high speed (around 55 mph) were the engine starts to sputter? Also, after changing to a 35 tooth rear sprocket I expected the DF should not have a problem going above 55 mph. Is that normal???
Sorry for the long post.
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Attachment 13158

Sorry, I will have pictures of my DF later.

I forgot to mention that the stock headlight was dimming as I revs the engine and that the headlight gets brighter as I applied the brakes. I have not ridden the bike at night since changing the new led halo headlight, but I seem to be ok now.

Quote:

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Originally Posted by Chi town

Hello everyone,
First of all, I like to thank everyone for all the great info. The info provided by ya has fixed some of the problems i had. Thank you guys. I bought my 2012 DF250 RTB-A from Killer Motorsports at the end of June and received the DF in the middle of July. Since then, I have not received my papers to register the DF. I regret buying from Killer Motorsport as they customer service sucks a$$.
Anyways, my problem with the DF is that I can't seem to get pass 55mp without the engine sputtering or choking, or it seem as it is cutting out.
When I first got the DF, it felt as the riding was heavy and it picked speed slow. But after reading this great forum, I adjusted the valve on the crank and the DF became better. The valves had no gap what so ever.
Here is a list of mods I have done to my DF:
- close out the secondary air system ( as it kept busting the hose)
- change the stock swear sprocket to a 35 tooth
- added a 108 main jet, and the mechanic did something to the pilot jet where it acts as a 45 pilot jet
- added 3 washers to the needle jet
- tried a reverse air ram with the new filter I bought on eBay. ( I will post that air filter pic soon) the reverse air ram didn't work as I was going 35-40 mph the engine would just die out. Put the stock filter back on and the engine did a lot of sputtering around 40 mph. So, I tried this other filter I ordered on eBay that looked similar to our stock air filter except it has a plate cover on top of the air filter. That filter resulted a smoother ride till the problem I'm having around 55 mph.
- changed all turn signals to led, along with a new led halo headlight
Is anybody having trouble at high speed (around 55 mph) were the engine starts to sputter? Also, after changing to a 35 tooth rear sprocket I expected the DF should not have a problem going above 55 mph. Is that normal???
Sorry for the long post.
Attachment 13157
Attachment 13158

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I have the same problem with my hoses for the secondary air system. I'm new to bike mechanics, so I was wondering how you went about closing it off and what any of the pros/cons of doing so might be.

Thanks
Tex

Quote:

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Originally Posted by Chi town

Hello everyone,
First of all, I like to thank everyone for all the great info. The info provided by ya has fixed some of the problems i had. Thank you guys. I bought my 2012 DF250 RTB-A from Killer Motorsports at the end of June and received the DF in the middle of July. Since then, I have not received my papers to register the DF. I regret buying from Killer Motorsport as they customer service sucks a$$.
Anyways, my problem with the DF is that I can't seem to get pass 55mp without the engine sputtering or choking, or it seem as it is cutting out.
When I first got the DF, it felt as the riding was heavy and it picked speed slow. But after reading this great forum, I adjusted the valve on the crank and the DF became better. The valves had no gap what so ever.
Here is a list of mods I have done to my DF:
- close out the secondary air system ( as it kept busting the hose)
- change the stock swear sprocket to a 35 tooth
- added a 108 main jet, and the mechanic did something to the pilot jet where it acts as a 45 pilot jet
- added 3 washers to the needle jet
- tried a reverse air ram with the new filter I bought on eBay. ( I will post that air filter pic soon) the reverse air ram didn't work as I was going 35-40 mph the engine would just die out. Put the stock filter back on and the engine did a lot of sputtering around 40 mph. So, I tried this other filter I ordered on eBay that looked similar to our stock air filter except it has a plate cover on top of the air filter. That filter resulted a smoother ride till the problem I'm having around 55 mph.
- changed all turn signals to led, along with a new led halo headlight
Is anybody having trouble at high speed (around 55 mph) were the engine starts to sputter? Also, after changing to a 35 tooth rear sprocket I expected the DF should not have a problem going above 55 mph. Is that normal???
Sorry for the long post.
Attachment 13157
Attachment 13158

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the sputter at top end is common and this bike has a top speed on a flat of about what your getting.
the sputter has proved to be a slight starvation for air at top speed. for me doing the reversed air ram with the stock filter was enough to fix it.
barone had tried taking the filter off completely witch temporarily fixes the issue.
another has tried a filter that allows more air flow.

Apparently that air scoop you bought forces way too much air even at moderate speeds.
it would be interesting to know if you could apply partial choke with that scoop on reversed and see what top rpm/speed is attainable.

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Originally Posted by BobbinInTexas

I have the same problem with my hoses for the secondary air system. I'm new to bike mechanics, so I was wondering how you went about closing it off and what any of the pros/cons of doing so might be.

Thanks
Tex

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Attachment 13159
What my mechanic did was cut the hose with the bracket that came from the engine block. He cut off half the metal nipple and welded it shut.
The left side of the pic, he just cover it with a plug that you can get at any parts store..
Hopes that help

Quote:

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Originally Posted by BobbinInTexas

I have the same problem with my hoses for the secondary air system. I'm new to bike mechanics, so I was wondering how you went about closing it off and what any of the pros/cons of doing so might be.

Thanks
Tex

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Closing it off has now on several occasions proven to prevent it from blowing out.
I think its necessary unless you find a braided or metal replacement.
That said the system is not needed.
You may get an increase in backfire without it, but who cares.
Ive found increasing your airflow almost eliminates the backfire.

Chi town and Tex,
You guys need to do a little searching and reading for answers to your questions. All have been discussed many times in this thread.

Chi town,
I have the sputtering problem and need a less restrictive air filter. Take you air cleaner off for a test run. When I did that, DF ran up to 7500 RPM with no sputtering.

Tex,
There is a lot of threads about removing the AIS. Take it all off, put a cap on the vacuum port on the intake, and make a plate out of aluminum to seal off the port on the engine.

Thanks Axa,
Yup, I had scoop facing the wind direction.
Will experiment the stock filter and the scoop again in the future

So, it's normal for the sputtering at top speed. That sucks.... So I guess my top speed is 55mph, sucks even more

Sorry Barone, I read the first 250 pages of this thread and from the time you came back on this thread. It seem the sputtering at top speed wasn't mention much till a few pages back till you said something.
Question Barone, as I am not so well knowledge about motorcycle mechanic. When you took off the air cleaner, did you had to adjust the air/fuel mixture as well?

Axa,
You mention that the air scoop filter I have brings much more air in. If I decide to use that air scoop in the future, will that mean I need a bigger main jet and maybe raise the jet needle some more?

Quote:

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Originally Posted by Chi town

Thanks Axa,
Yup, I had scoop facing the wind direction.
Will experiment the stock filter and the scoop again in the future

So, it's normal for the sputtering at top speed. That sucks.... So I guess my top speed is 55mph, sucks even more

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Yes, though I said sputter is common not normal, by no means should you accept it. It can be eliminated tuning your airflow, I know that for a fact.
For me it meant top rpm from 6.5k to 7, with allowed a few mph increase on top end in the most optimal conditions. For me that is a very worthy modification.
I haven't even touched my jets or needle yet.
I will when i find a proper air scoop Ill try bumping the main jet way up, but I'm not expecting much if any improvement on the top end from it.

I saw that scoop you bought off ebay sometime ago, but speculated it was too aggressive as it has a very concaved intake. You seem to have confirmed that.
I am looking for one with a wider area but no concavity, or even some convexity.
I may need to fabricate something when time allows, cuz i am not finding what i want.

So that's why i feel the most important mods you can make to improve the top end is lowering your sprocket ratio, and eliminating any sputter.
Ultimately, this bike's top speed will largely depend on its lack of power because of drag.
And at highway speed the resistance apparently increases by an exponent. Here is an interesting read about it click to see the full article:
At low to moderate speeds, during stop and go driving for instance or while you're motoring around town the affect of drag is negligible, don't confuse this to mean non-existent, any serious bicycle racer can tell you it isn't, but as far as motor vehicles go, as long as we stay under about 50 mph it accounts for only about 5% of a vehicles total resistance to movement. Unfortunately once we reach highway speeds, roughly 60% percent of a vehicle's energy is required just to defeat air resistance, and that grows exponentially as speed, and with it air velocity, increases. If you've ever fought a stiff headwind you know exactly what I'm talking about. Riding into the wind you have to twist the throttle up like an alarm clock spring just to maintain headway. With the wind at your back, you can reach the same speed on half the throttle. Think of drag as a never ending headwind, and you won't be far off the mark.

Thanks Axa

Quote:

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Originally Posted by Chi town

Sorry Barone, I read the first 250 pages of this thread and from the time you came back on this thread. It seem the sputtering at top speed wasn't mention much till a few pages back till you said something.
Question Barone, as I am not so well knowledge about motorcycle mechanic. When you took off the air cleaner, did you had to adjust the air/fuel mixture as well?

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Chi town,
I just removed the air cleaner and did not change anything and she ran up to max rpm without sputtering. I put the air cleaner back on and and she sputtered so I assumed that the stock air cleaner is too restrictive for my DF with 108 main, 42 slow, and the catalytic converter removed. I could be wrong.

She pulls real good up to about 5500 RPM when the cutting out occurs with the stock air cleaner installed. I ordered some other air cleaners off Ebay to try. Might go back to a 105 main to see if the sputtering stops but will wait for the new air cleaners.

I had a 2010 DF and don't remember having this cutting out problem.

Thanks Barone

Quote:

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Originally Posted by Chi town

Axa,
You mention that the air scoop filter I have brings much more air in. If I decide to use that air scoop in the future, will that mean I need a bigger main jet and maybe raise the jet needle some more?

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I don't honestly know if you will ever be able to balance that scoop, but my speculation is the convexivity is just too much, thus catching too much air at speed.
if it was dying at a particular throttle % you could try particular carb adjustments.
but I don't know what the cure would be for too much air at higher speeds without effecting performance at lower speeds.
try running with some choke applied, but as you bumped your needle and perhaps ur mechanic increased the throttle on your piolt jet with the air/fuel mix screw, less air is not likely what is needed at these points.
you could manually apply the choke at speed but that would get annoying.

anyway I would recommend making as few adjustments at a time, learning from them as you go

Quote:

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Originally Posted by Chi town

Sorry, I will have pictures of my DF later.

I forgot to mention that the stock headlight was dimming as I revs the engine and that the headlight gets brighter as I applied the brakes. I have not ridden the bike at night since changing the new led halo headlight, but I seem to be ok now.

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Yea thats a weird thing I keep meaning to post. My headlight dims as the bike revs and it gets brighter when I hit the brakes. The 2012's seems to be coming rich from the factory so i would change back to the 105 main and remove those needle shims. I was having cut outs also.. I took my entire carb apart... and re-adjusted the air fuel fix.. put the stock jets back in... I also changed to a closed ended air filter with better filtration. I am able to creep over 60 mph on flat ground now. First and second gear are almost useless even with a 35 tooth. First gear should have the most torque but it feels crap.. second is about the same.. but once into 3rd it feels like a different machine. Much more power 3-4-5 than 1 and 2. Sometimes it's embarrassing to have to full throttle the first 3 gears just to keep up with the acceleration of traffic...and everyone looks at you because the bike sounds like your going 100 when you are just struggling to get to 25mph. Idk.. each bike is a little different even though they are all made the same way... because these are cheaply made Chinese bikes. with poor quality control at the factory... the specs may not all be exactly the same.. and im almost 100% sure things do not get adjusted to spec (valves, carb, chain) so you just need to keep fiddling with it.. You'll get it there eventually.. I have my carb with stock jets.. with the mixture set just about 2.5 turns out maybe a hair less. I have yet to check my new plug... but regardless if it is running rich or lean with my current setup... it drives perfect with no cut outs.. so Im not going to touch it.. although i may try the ram air just because it looks cool visually. Good luck with the bike!



Can you link us where you got the headlight and the turn signals?

okay i just bought a set of these http://cgi.ebay.com/ws/eBayISAPI.dll...tchlink:top:en

I think this should drop the bars about 2 inches from where they are now. I want them down low.. not quite cafe racer low.. but I think they look a little off with the stock setup

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Originally Posted by Bobthebobber

Yea thats a weird thing I keep meaning to post. My headlight dims as the bike revs and it gets brighter when I hit the brakes. The 2012's seems to be coming rich from the factory so i would change back to the 105 main and remove those needle shims. I was having cut outs also.. I took my entire carb apart... and re-adjusted the air fuel fix.. put the stock jets back in... I also changed to a closed ended air filter with better filtration. I am able to creep over 60 mph on flat ground now. First and second gear are almost useless even with a 35 tooth. First gear should have the most torque but it feels crap.. second is about the same.. but once into 3rd it feels like a different machine. Much more power 3-4-5 than 1 and 2. Sometimes it's embarrassing to have to full throttle the first 3 gears just to keep up with the acceleration of traffic...and everyone looks at you because the bike sounds like your going 100 when you are just struggling to get to 25mph. Idk.. each bike is a little different even though they are all made the same way... because these are cheaply made Chinese bikes. with poor quality control at the factory... the specs may not all be exactly the same.. and im almost 100% sure things do not get adjusted to spec (valves, carb, chain) so you just need to keep fiddling with it.. You'll get it there eventually.. I have my carb with stock jets.. with the mixture set just about 2.5 turns out maybe a hair less. I have yet to check my new plug... but regardless if it is running rich or lean with my current setup... it drives perfect with no cut outs.. so Im not going to touch it.. although i may try the ram air just because it looks cool visually. Good luck with the bike!



Can you link us where you got the headlight and the turn signals?

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I don't personally believe it's a much a problem with quality control out of china.
Surely they are not adequately installing valves, i cant argue with that at all.
But my carb was marked and adjusted, likely to their factory settings when they ran and tested the engine. I would argue they must adjust all to settings that would run at their factory.
And we can debate if a snug chain is improper on a bike with no suspension...
I would argue its adequate if not superior to one that is loose.

But rather the variances are in each of our individual conditions and perceptions.
For instance, many of us have the cut out problem, which by all accounts is a starvation for air @ WOT top rpm and the engine riches out. But the first thing so many of us are doing is upping jets and shimming needles to make an an even richer mix...

Which leads me to ask about this filter you had added which apparently solves this max rpm sputter. If it is not reversed or otherwise catching air, I question what would lead you to believe it had "better filtration"?
For a better filtration by definition will add to the impedance of air flow, so this is not making sense to me.
Not trying to be a douche, just curious to learn if there are indeed factual differences in airflow for different filter designs. The stock mushroom type vs the closed end type you purchased.
If there is a filter design that in fact catches smaller particles and provides better airflow, without having an enlarged filtration area, id like to use it instead of being on the hunt for an adequate scoop that seeming doesn't exist.

its a 0 sum game, im either pointing a more restrictive, better filtering device into the wind, or your using a less restrictive poorer filtering device in stock configuration, or perhaps it has an enlarged area compared to stock.

Would you post the measurements of size of your filter's element area? and/or a link to it?

BobtheBobber,
I got the headlights from eBay. The seller is called chevyracer57. The item description is 5-3/4 white halo halogen h4 bulb headlight angel eye led.
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Attachment 13161
The turn signals I bought from amazon.
Sorry I can't get a copy of the Internet address, but you should be able to find those in amazon by punching led turn signals.
I kinda regret that I bought the chrome. As with the chrome on our DF, these chrome led turn signal are cheap. The rear led turn signal wires were short, so if you decide to buy, expect to have wires in hand for extension

Anyone think I should buy a tachometer? Will a tachometer make tuning easier for me and more precise?
I haven't had any success in tuning the carburetor. It seems I can never get it right.

Went out for a midnight ride... wow cant see a thing... Low beam is usless.. high beam even more so. Everytime i rev the engine the light dims.. when i apply the brake it gets super bright. the 2012 has a flash button that flashes on the high beams. It almost seems like the when applying the brakes it trips this switch. I just duct taped the flash button down with the lights on the low beam setting. This made both the low beams and high beams go on at once... and stopped the dimming from the revs and the changes when applying break. Im going to hard wire it so that the flash switch can be on all the time without having to hold the button. Im going to wire it to the highbeam light so when the high beams are on, it just effectively applies the flash setting and leaves it on

Chi town,

You said you bought it from Killermotorsports. I bought mine from the same company (in name) in DFW and yes they have the worst customer service I have ever seen. But at least I did get my reg and lic for TX from them even though it took for ever. Is this the same company you ordered yours from?

They have never sent me a replacement shift rod which was under warranty and every time I ever called or emailed them about an issue it was like talking to a wall. Their customer service reps just simly dont care at all once they have your cash.

Looking at their web page I see they went back to selling scooters only again. The DF250 is no longer on there.
But luckily it doesnt take a rocket scientist to work or fix stuff on this bike.

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Originally Posted by GonzoX

You said you bought it from Killermotorsports. I bought mine from the same company (in name) in DFW and yes they have the worst customer service I have ever seen. But at least I did get my reg and lic for TX from them even though it took for ever.
Looking at their web page I see they went back to selling scooters only again. The DF250 is no longer on there.
But luckily it doesnt take a rocket scientist to work or fix stuff on this bike.

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^^ killer for me also , but I never expected any customer service :p

used sheetmetal to cap off air inject

and for 1st 3-5 months I carried a screwdriver in pocket , I'd make a highway speed run , if it sputtered or acted funny , id chop my kill switch roll to side of road and add/remove 1/2 a turn from my air fuel mix , until I found the sweet spot for my temperature/altitude


direct copy/paste from my common problems post - dimming headlight problem, really easy to unplug the blue and white wire from the dark green wire and plug it into the other blue and white wire like it should have been been in the first place. now my light switch works and my lights don't dim

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Originally Posted by Chi town

Anyone think I should buy a tachometer? Will a tachometer make tuning easier for me and more precise?
I haven't had any success in tuning the carburetor. It seems I can never get it right.

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Attachment 13162

Here is my tach which is an inexpensive one from Ebay. Internal battery so easy to install with a wire wrapped around the spark plug wire, ground wire hooked up, and zip tied to the handlebars. Can be temporary while tuning or left on. It is slow to react but seems accurate compared to my Harmonizer being held in my hand.
http://www.ebay.com/itm/New-Tach-Hou...5df5ad&vxp=mtr
Also has an hour meter.

" because these are cheaply made Chinese bikes. with poor quality control at the factory"

I do not agree with this statement. I think the quality is good on my 2012 DF. Not great but good. I really enjoy working on it. I also really enjoy riding it keeping in mind that it is a 229 cc push rod engine.

Sometimes I might seem harsh in my comments about recommending these bike to newbies.
These bikes are like most bikes where "you are on your own" (ie. no dealer close at hand) and require some knowledge of mechanics. I do not recommend them to people that have not done service and repair on vehicles.

My $15,000 Ural Yamal is about the same quality wise. My Kawasaki W650 (worth about $4500) is better quality but still requires wrenching. I don't take any of my vehicles to dealers for service and repair except warranty work which usually does not happen.

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Originally Posted by DanDaMan

direct copy/paste from my common problems post - dimming headlight problem, really easy to unplug the blue and white wire from the dark green wire and plug it into the other blue and white wire like it should have been been in the first place. now my light switch works and my lights don't dim

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Not the same on the 2012 DF models.

Post #s 4314 and 4315... couldn't have said it better myself !

Even My Triumph had a few glitches that had to be upgraded/fixed. All manufacturers are trying to save a dollar or two and some times use less than optimal products. The cheapest that will work,in all areas of the world.
Re: smaller wire size, mild steel fasteners,single wall exhaust pipes,etc.

GonzoX,
I called my C.C last week and did a chargeback bc Killer Motorsports haven't send my MCO. It had been a hassle dealing with them about my MCO. Till I receive my MCO, I'll release the payment.

Barone,
Thanks Bar, that's a great price. I'm ordering that now

Here's my 2012 DF...
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Originally Posted by Chi town

Here's my 2012 DF...

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Looking good. I see wrapped exhaust, smaller turn signals, and removed stripes from tank. Did you repaint the tank?