Dong Fang DF 250 RTB Bobber Information

Is that you Prodigit from the scooter forum ? Anyway, These OHV only have so much HP. If you gear them to tall they won't pull the gearing unless your 5'5 and 105 lbs.. I'm 6'3 and 255 lbs. I changed my factory gearing to 16/38 . It was just a little to tall. Just wouldn't pull it worth a darn with my big wind catching ass on it. I had to drop one tooth on the front (worth 3-4 teeth on the rear) At 62 indicated (actually 57 or 58) and got 80 MPG . That's about the best I can do with it. Hell, my Ninja 250 can get 70 or better at that moderate speed.

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Originally Posted by axa

http://www.mychinamoto.com/forums/im.../confused1.gif Is it just me or can everyone else make heads or tails of this?

maybe you should start that RTC thread...

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Its all rocket science and greek to me LOL. Not that advanced. All I want is a reliable bike mainly. Will work up from there. So far she has not let me down but there are a few issues that I still have to address. Tank leak is #1 issue but its a slow leak. Other than that she runs and she gets me accross town. Happy about that. My main issue is the poor mettalurgy and rust right now.

Love the info and will record it and save it for the future for sure. It will come in handy later Im sure. But Im still a noob so Im just recording it and saving it right now LOL.

I do agree about the stock gearing though. Good God I have to change gears three times just to get out of cars ways after a red light. But I expect that from a sub 250cc engine. That's why Im going to ask axa for a loan to buy something with 500cc or bigger.

In all honesty I was going to buy two sub 50cc scooters for the same amount hoping that my new wife would warm up to hers. I am SOOOOOO glad I got this instead. Sometimes ya just gotta splurge on yourself because nobody else will. That's for damn sure. No regrets!

Now where did I put my rum?

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Originally Posted by 4950cycle

Is that you Prodigit from the scooter forum ? Anyway, These OHV only have so much HP. If you gear them to tall they won't pull the gearing unless your 5'5 and 105 lbs.. I'm 6'3 and 255 lbs. I changed my factory gearing to 16/38 . It was just a little to tall. Just wouldn't pull it worth a darn with my big wind catching ass on it. I had to drop one tooth on the front (worth 3-4 teeth on the rear) At 62 indicated (actually 57 or 58) and got 80 MPG . That's about the best I can do with it. Hell, my Ninja 250 can get 70 or better at that moderate speed.

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Yup, is me.
On the BMS TBX260 I have a 100:1 ratio RPM over MPH, and the bike goes 82MPH. It's 256cc fuel injected though...
I use this RPM over MPH ratio, because it's indiscriminate against CVT or manual geared bike.

On the 150cc TaoTao I have a 116:1 gear ratio (or 7k RPM @ 60MPH); and it tops out at 63MPH GPS verified.

Those bikes accelerate just fine, save for near the end of the variator, where speed creeps those last 10-15MPH to top speed. You know that on those scooters they have maxed out their gearing on those engines.

I know they are different engine types, but even with different engine types, you should get a certain amount of speed for a certain amount of CC's.
The Bobber is probably the least aerodynamic bike of them all (RTA, RTC, RTC-B, RTD); so wind drag may eat a couple of mph from the top speed.

If the gearing is too heavy, you could always upshift one gear, for better acceleration.
I guess I'm lucky at 100LBS lighter.

BTW, I finished reading the first 114 pages of this thread.
Seems like some people get the RTB-A (which is with black hardware) and some get the regular RTB (with chrome hardware).
Get the RTB-A if you can. Black means less rust!

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Originally Posted by GonzoX

That's why Im going to ask axa for a loan to buy something with 500cc or bigger.

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your loan has been approved!

but what in tarnation makes you you believe that i have any money

i really want more engine. ive been scouring craigslist

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Originally Posted by axa

i really want more engine. ive been scouring craigslist

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Consider a USED(low price) Honda Rebel 250/234cc or a Yamaha XV250/249cc motorcycle. Both have been around for over 20 years and can be "modded" into bobbers. They are solid enough so that age really does not matter(parts have remained available and unchanged over the last 10 years).

C.A.R.B. compliant too!

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Originally Posted by axa

i really want more engine. ive been scouring craigslist

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axa,
I ordered the engine you PMed me about but it turns out to be an ATV engine and the price was wrong. So the guy is refunding my money.

His email. Honest mistake. We knew it was too good to be true.:lol8:

"Hi Vincent, turns out I made a mistake, actually 2.
First it’s the wrong engine, you need 65534 (I have modified the description)
I also messed up on the price, I had most of them ok but the 65532 was wrong at $494.93 it’s actually under my cost plus I need to cover for shipping.

So here are the options, I can refund you for the order or you can pay an extra $230 for the 65534 engine?

Let me know what you want to do, I’m very sorry about this."

Now corrected listing at
http://www.mbe-motorsports.com/catal...roducts_id=388

Correct engine for our DFs at
http://www.mbe-motorsports.com/catal...roducts_id/389

Still tempting but the search continues. Maybe a "big bore kit" is the way to go.
Now that I have the cutting out problem solved with my new foam air filter I'm good for a while.

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Originally Posted by SR.MAILMAN

Consider a USED(low price) Honda Rebel 250/234cc or a Yamaha XV250/249cc motorcycle. Both have been around for over 20 years and can be "modded" into bobbers. They are solid enough so that age really does not matter(parts have remained available and unchanged over the last 10 years).

C.A.R.B. compliant too!

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i would hesitant and not too unsure to say that neither of these motors will fit.
The dual exhaust on the rebel will not fit nicely with the double cradle.. i dont know what the frame is called but to split cradling tubes on our bike will get in the way of the dual exaust.
I would also be hesitant and say the V cylinders on the Yamaha would be a tight if not impossible fit. Our carbs with filters hardly do.

Else i would have this already!!! yup thats right Honda Rebel with 950 miles 500$ screw the title work.

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Originally Posted by barnone

axa,
I ordered the engine you PMed me about but it turns out to be an ATV engine and the price was wrong. So the guy is refunding my money.

His email. Honest mistake. We knew it was too good to be true.:lol8:

"Hi Vincent, turns out I made a mistake, actually 2.
First it’s the wrong engine, you need 65534 (I have modified the description)
I also messed up on the price, I had most of them ok but the 65532 was wrong at $494.93 it’s actually under my cost plus I need to cover for shipping.

So here are the options, I can refund you for the order or you can pay an extra $230 for the 65534 engine?

Let me know what you want to do, I’m very sorry about this."

Now corrected listing at
http://www.mbe-motorsports.com/catal...roducts_id=388

Correct engine for our DFs at
http://www.mbe-motorsports.com/catal...roducts_id/389

Still tempting but the search continues. Maybe a "big bore kit" is the way to go.
Now that I have the cutting out problem solved with my new foam air filter I'm good for a while.

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the while you will be 'good' for, is about a week....

whats the difference in the links? they still look the same except for the part number.

Should have figured though, from his initial answers it sounds like he hasn't ever even sold one of these...


id be all over a bigger bore. It would likely be the least costly, and provide me a practice cylinder to learn to bore on my own.

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Originally Posted by axa

your loan has been approved!

but what in tarnation makes you you believe that i have any money

i really want more engine. ive been scouring craigslist

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I know bro, Im just kidding.

I know what I want but its $7k. A Royal Enfield. Only other issue is Im a short fat old guy and Ill have only one foot on the ground on one of these since the bullet is something like 6inches higher than my DF. Been told that this should not be an issue since many riders have bikes and use only one foot at park or take off. I hope they are right but Im a noob and this seems a bit uncomfortable to me. Ill trust the judgment of veteran riders though.

I do have my eye on a Honda 750 and it feels good. Both feet flat on the ground and it has more power. Its used and costs about the same as a new RE. Thing is, I have this longing for a retro bike and both the DF and the RE fit that niche. The older bikes just look right to me for some reason.

And for the record I will be watching any engine swap outs here with a microscope. AFAIK this has not yet been done on the DF. Should be an interesting if not entertaining thing to read about. Just dont see a whole lot of room on the frame for anything bigger unless it has a bmw style engine with the heads and cylinders on the sides. And IMHO that would look all kinds wrong on the DF. Not to mention that I think BMW has a trade mark on this like Harley did on the V way back when (Ural doesnt count) LOL.

Stay with the used Honda shadow 500cc or bigger,if the budget allows.

I researched a new Royal Enfield and what I discovered is that they upgraded the fueling to EFI and ignition to solid state.
The improvement did little for gas mileage and you still have the OLD base engine(push rod).

My Yamaha will keep up with one,due to horsepower to weight difference.

As you can see from My signature, I ended up with a Triumph T100 (looks like a 1960's model) has state of the art hidden components.
I was able to gain 12 rear wheel horsepower, just by "adjusting" the engine management in the ECU.
I do not want to go fast, but I do want what the engine puts out... before the EPA got to it.
53mpg is MORE than a 47mpg stock engine put out. This is My long haul/highway machine(when I need to go faster than 50mph).

I really like having both feet on the ground. And i like being low when in motion, and at 5'10 the DF doesn't make me have to bend too much at the knee, and i feel is comfortable being a hard tail.
I also think this hard tail old school bobber looks a world better than any other cruiser style out there. In fact that's what sold me on getting a bike again, until i noticed hard tail bobbers, i thought most cruisers were horrible looking.

So yesterday me and some refigerated mini truck to the left, line up at a red light...
It is the base of a half mile low grade incline, on the way to work each morning.
So what do the cars, rushing to get to work do, they line up behind me, thinking, this bad ass bike is going to blow up the road...
Well, i got the jump on the truck, but apparently not enough that the car on my rear felt they could squeeze in on and get around us...

It was perhaps the longest and most embarrassing 60 seconds of my life... which only would have been worse if i were in the left lane... Which is why I never line up in the left lane...

I need a new engine... I measured about 2 inches that our engine could slide towards the front, i think a V twin may be back in the running...

barone if your willing to put up $700 for the 170fmm, you might be better off with this.
$975 shipped, best price on model so far...

but for that price perhaps I should be looking for an used bike with a small v twin, and do an engine swap.

http://yhst-56702395775911.stores.ya...t/li25ven.html

That's a really weak engine for a 250 v twin.

It's too sad that there are so few bikes out there, that are between 250cc and 500cc.
In fact, most entry motorcycles in the stores are 650cc's, and to me they're just too heavy.
Not only too heavy, but have too much power, used for the tracks, not the streets!

I think a true 250cc thumper might be the best mix between fuel economy and versatility.
However, if you need to ride on the highway often, you need a 400cc or more.
The 300cc's (like eg: the Ninja 300) are good bikes, but they can't last revving too long in high revs, even though they easily can do peaks of 100+ MPH.
For long distance interstate riding, a 250 will have to run WOT, a 300cc Ninja runs at ~ 8k RPM (they're tuned to run upto 11k RPM stock), but with a 400cc you could do 80MPH @ an acceptable ~4-4500RPM; and 60MPH at a comfy 3k RPM easily; when geared right!

You'd probably be able to hit 80MPG with a bike like this, but the 650's are all in the 55's of MPGs, and the 250's are 80MPG, only because MPG drops drastically when running an engine at WOT.

350cc would probably be the best of both worlds... I don't understand why Jap and USA factories don't see this???
They literally have to wait for the Chinese to fill the gap? (like they did with the 50cc, 150cc, and now 250cc's too)?

Well, perhaps some clever Chinese engineer will be able to add a piston to the existing 150cc engines, getting a V-twin, or P-twin 300cc motor, or sees the need to give the Chinese government more power, and provides the local police corps with 350cc thumpers instead of their 250cc Lifan V-twins.

kiss of the df tailpipeAttachment 13475 this is how it is after 2 weeks. no more pain now though.....LOL

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Originally Posted by freezerboy

kiss of the df tailpipeAttachment 13475 this is how it is after 2 weeks. no more pain now though.....LOL

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LOL I can relate to this. It took at least four or five heat burn scabs for me to get some respect for the exhaust pipe. My wife used to always give me grief about it.

I guess I'm lucky to have an exhaust cover plate!

I wouldn't mind havhis engine on the DF. Johnny Pags Ventura 320I
Attachment 13476

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Originally Posted by Chi town

I wouldn't mind havhis engine on the DF. Johnny Pags Ventura 320I
Attachment 13476

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Looks like a parallel twin, they sound more racing bike/2stroke; less bobber.

That is what a made in USA bobber is, if you read the specs on their web site.
I guess the extra 100 pounds is from the water cooling and real stainless steel.
The $5200.00 is also made in USA. (you want to play...you have to pay).

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Originally Posted by SR.MAILMAN

That is what a made in USA bobber is, if you read the specs on their web site.
I guess the extra 100 pounds is from the water cooling and real stainless steel.
The $5200.00 is also made in USA. (you want to play...you have to pay).

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What makes you think this is made in US?
Read this they talk about how the bikes being made in China. Make it in the US and watch that $5200 price tag double.

That said, there are still those whom indiscriminately believe it will be a better product just becuase its made in the US, That may or may not prove true, but what proves true is the inflated price tag.
Inversely, some believe it will be worse cuz its made in china.

Products will be as good as they can stretch the money that spent in production, that stretch goes further outside of the US. There are many good products manufactured in China, like smart phone and what not, there is also a lot of crap.
Usually the crap is very inexpensive, but the good is never inexpensive, just still usually less expensive than if made in the US.

That said, this is a nice small Chinese made bobber, with the a small yet adequate engine. for me it doesn't justify the 210% price tag vs the DF RTB, even if it were actually made in the US

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Originally Posted by SR.MAILMAN

That is what a made in USA bobber is, if you read the specs on their web site.
I guess the extra 100 pounds is from the water cooling and real stainless steel.
The $5200.00 is also made in USA. (you want to play...you have to pay).

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Yeah,nooooo.They are designed in the US and built to spec in China land.Oh wait,most of the US has moved to China so I guess that's partly correct.

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Originally Posted by ben2go

Yeah,nooooo.They are designed in the US and built to spec in China land.Oh wait,most of the US has moved to China so I guess that's partly correct.

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"Designed in the US", is almost, not as quite, but almost as a useless statement as made in the US.

Someone school me to what they believe makes a motorcycle design by someone who is physically located in the US, any better than one designed by someone outside of US boarders?
Are other nationalities, races, or cultures are unable to do this?
If we were taking about any advanced process industries, biotech, nanotech... then a case could be made that the US has the best environment in industry or eduction, but a small motorbikes?

This is just the way it goes. I've had to do this in the electronics and software industry occasionally over the years.
You shop around for a company that has the capability, better yet they already have developed what you want. You then pitch your specs or modifications. They massage their products or create one the way you want, then you shop and market the product.
True in many industries.

Ive dissected competitors products and find very same reference design from the very same Asian manufactures. Thats one way I know who to call.

Who knows what or where Pag designed or didn't his bikes.
But this "designed in the US" thing with bikes and other products, has one purpose, giving the false sense that it is a better product than it is... and thus justify any premium cost, as i see, it seems to work.

heres maybe a deal for someone who can find this place
used 250cc lifan v twin $399
all i can gather is they are somewhere in the Central Time Zone

I'm a little behind on the thread, reading up on it right now,
Just 2 questions,

1- By how much is the speedo off? (indicated MPH vs GPS verified MPH)?

and

2- Since the engine has a big bore, I can imagine the engine vibrations are caused by an incorrectly balanced counter weight, as the newer piston is both larger and heavier than the stock 125cc piston.
So my question is, has there been any remedy, or easy fix to counter the vibrations, or is the only way to re-balance the counterbalance?

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Originally Posted by ProDigit

I'm a little behind on the thread, reading up on it right now,
Just 2 questions,

1- By how much is the speedo off? (indicated MPH vs GPS verified MPH)?

and

2- Since the engine has a big bore, I can imagine the engine vibrations are caused by an incorrectly balanced counter weight, as the newer piston is both larger and heavier than the stock 125cc piston.
So my question is, has there been any remedy, or easy fix to counter the vibrations, or is the only way to re-balance the counterbalance?

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i measured it off nearly 10% exactly.

i dont have vibration.

No significant vibration on my DF either. Odometer appears to be off by 18%. I need to verify that.
I'm not sure about the speedometer.

I get vibration but foam grip covers help alot. I did not use a gps but had my wife drive behind me in my truck and my speedo appears to be 100% correct.

After 2 months, three letters back-and-forth with the on-lihe seller, 4 trips to the DMV and 1 rider safety course, my DF is finally legal. I have made no modifications yet, since I wasn't sure if I'd be able to keep it or not. Here are 3 pictures from my first (legal) ride today, plus one extra pic for any aviation history buffs out there...

Attachment 13567Attachment 13568Attachment 13569Attachment 13570

:clap::thumbsup:ConGrAts:clap::thumbsup:

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Originally Posted by Nick Papageorgio

After 2 months, three letters back-and-forth with the on-lihe seller, 4 trips to the DMV and 1 rider safety course, my DF is finally legal. I have made no modifications yet, since I wasn't sure if I'd be able to keep it or not. Here are 3 pictures from my first (legal) ride today, plus one extra pic for any aviation history buffs out there...

Attachment 13567Attachment 13568Attachment 13569Attachment 13570

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Originally Posted by Nick Papageorgio

one extra pic for any aviation history buffs out there...

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FastDoc on Chinariders.net (and here, I think?) is a licenced pilot.

I guess in some cases, the CCW Heist would make things a lot less painful as far as getting one of these registered. The 2nd longest thread here on mychinamoto about the CCW Heist was started by Gardo when he had bought one of these and could not register it in New Jersey.

Then again, this thread is somewhat out of place here on MCM considering the majority of the threads are Europeans and European ex-pats living in China. But, please, keep it up, because it is one of the very few threads I can relate to here as a North American! LOL