Dong Fang DF 250 RTB Bobber Information

**bowtiewagon** · 09-21-2015, 03:29 PM

All my mods are done, now she is just a daily rider, almost 16,000 miles and still rockin the roads. I am replacing my Master cylinder for the front, as the last one I purchased was a bit smaller, and i was not comfortable with it, in the meantime, I also bought a new left hand clutch handle to match.Both cost me like $25 total. Pleased there. Gonna order some more brake pads for front and rear, just to have around. I also managed to modify my throttle cable.Bought a cable the closest length from the U.K., then hacked the little sleeve that separates the accelerator pump cable and the accelerator cable, works great.

All and all, I guess it is all about the luck of the draw with these. I hear some of you having major issues, where as I have only had those mild ones, that I figure would probably happen. I always remember you get what you pay for.This bike was cheap from the get go, the parts have been difficult at times to acquire when needed, but not impossible. And the fixes and repairs I have done over these couple years, still are cheaper than buying those over priced brand names, and I like it better. More to me than those would have been.

**axa** · 09-21-2015, 06:33 PM

Originally Posted by barnone

axa,

BTW, what nonsense posts are you referring to?

I dont know , lets just say i like reading more technical sort of posts..

On a related note, anyone find evidence the carb accelerator pump does anything for them?
I ditch mine and don't notice a difference, though i surely have the most atypical engine

**barnone** · 09-21-2015, 07:18 PM

I'm just enjoying riding mine here in the mountains.
IMG_20150907_125942.jpg
At the Cheoah Dam AKA the Fugitive Dam

**moilami** · 09-21-2015, 08:48 PM

Originally Posted by barnone

I'm just enjoying riding mine here in the mountains.
IMG_20150907_125942.jpg
At the Cheoah Dam AKA the Fugitive Dam

What there is not to like of that? That's a brilliant bike. When tons of more is begun to clutter that, then a question rises is someone compensating something with his bike or just plain attention whoring

**ben2go** · 09-22-2015, 02:46 AM

Originally Posted by axa

I dont know , lets just say i like reading more technical sort of posts..

On a related note, anyone find evidence the carb accelerator pump does anything for them?
I ditch mine and don't notice a difference, though i surely have the most atypical engine

The accelerator pump is supposed to supply fuel when the throttle is opened quickly and prevent fuel starvation.

**axa** · 09-22-2015, 05:14 AM

Originally Posted by ben2go

The accelerator pump is supposed to supply fuel when the throttle is opened quickly and prevent fuel starvation.

OK. thanks for your contribution.

Id like to focus on the original question though, has anyone found evidence that this engine at all benefits from the pump.

as mentioned I've found no benefit but I can't determine at which point of a heavily modified engine that may have been lost or if its NON THEORETICAL purpose was ever warranted.

**Zorge** · 09-22-2015, 06:22 PM

Originally Posted by axa

a few months back i posted my work with larger valve and seats, but the only feedback i got was a lot unsubstantial nonsense.

Wait a second!

Are you referring to this thread: http://www.mychinamoto.com/forums/sh...-modifications ?

There are only your and my posts?

So... "unsubstantial nonsense" you said?

**axa** · 09-22-2015, 06:40 PM

Originally Posted by Zorge

Wait a second!

Are you referring to this thread: http://www.mychinamoto.com/forums/sh...-modifications ?

There are only your and my posts?

So... "unsubstantial nonsense" you said?

how did you make that connection?
you and i seem to be the only few with this level of interest.

**Zorge** · 09-22-2015, 07:42 PM

Beats me! It looks that something was lost in translation!

About carbie: I think that some CV carbie would do better job (for everyday riding) than plans slider type with acceleration pump.

But, IMO, there is one big thing that limits you significantly - this pushrod design with only one lobe and, as you realized earlier, non existing tuning cams.

Everything else you've already done....

BTW, did you tried to measure compression (not compression ratio, which is anyway just arithmetic mean)? You know... gauge, hose, spark plug hole, cranking... and result in... what you use in your part of the world - PSIs? On dry and with few cc of oil inside cylinder?

As you can see, my English limits me a lot, so I would mention few things for you "to think about". I'm not regular in this thread, so I'm sorry if I missed some mods on your bike.

If you already experiment with low octane gasoline and increased compression, you could think about buying adjustable or programmable CDI unit. Those adjustable are available at "Aliexpress". It could be handy to have possibility to adjust ignition angle and smooth engine's running.

Another thing is oil cooler. There are some kits with engine head cover with oil inlet and outlet, set of hoses and radiator, and what is important, it is "bolt-on" solution.

I believe that adjustable ignition and oil cooler could, if not prevent, than at least reduce, engine surges you mentioned half a year ago.

**axa** · 09-22-2015, 07:53 PM

Originally Posted by Zorge

Beats me! It looks that something was lost in translation!

About carbie: I think that some CV carbie would do better job (for everyday riding) than plans slider type with acceleration pump.

But, IMO, there is one big thing that limits you significantly - this pushrod design with only one lobe and, as you realized earlier, non existing tuning cams.

Everything else you've already done....

BTW, did you tried to measure compression (not compression ratio, which is anyway just arithmetic mean)? You know... gauge, hose, spark plug hole, cranking... and result in... what you use in your part of the world - PSIs? On dry and with few cc of oil inside cylinder?

As you can see, my English limits me a lot, so I would mention few things for you "to think about". I'm not regular in this thread, so I'm sorry if I missed some mods on your bike.

If you already experiment with low octane gasoline and increased compression, you could think about buying adjustable or programmable CDI unit. Those adjustable are available at "Aliexpress". It could be handy to have possibility to adjust ignition angle and smooth engine's running.

Another thing is oil cooler. There are some kits with engine head cover with oil inlet and outlet, set of hoses and radiator, and what is important, it is "bolt-on" solution.

I believe that adjustable ignition and oil cooler could, if not prevent, than at least reduce, engine surges you mentioned half a year ago.

lets take it over to the enthusiast thread.