Dong Fang DF 250 RTB Bobber Information

[axa]

After only 20 miles of trouble free riding the first day, I have now noticed on only my second day riding, after only about 10 more miles that I suspiciously have the same problem of the engine just dying on me.
First time it happened, first trip on the highway doing no more than 45 (50 indicated) it started to backfire and losing power around the same time. Then as I pulled off slowing down it happed, a stall as soon as I stopped giving much throttle.

Sat a few minutes because just at that time I noticed the tube just out of the secondary intake port near the head had burst. So I trimmed it back and reattached... so after a 20-25 min rest I was on my way home. But 5 min later just seconds from home, the same thing backfire/spudder and stall when rolling in my driveway.

Sat again, this time olny 5-10 min, took it for a test ride across in a parking lot across the street, and in 5 min same shit again.

The first days ride seemed to go without a hitch, 20 min each way to work and back. Only difference might have been i was real soft on the throttle, and there was no initial indications of a problem ...

I don't like where this pandemic seems to be going.

Hey guys, I posted a while back. Got my bike and I love it... but can't seem to get the dang thing running right.

Here are the symptoms:
It will bog down then die when going 52 mph (fully open and as fast as I can go) never really went further than 1 mile at full speed.
Sometimes it will stall when I am down shifting.
Occasionally hard to start when cold.
Whenever it dies on me I have to wait about 5-10 mins before it will fire up again... then it will go about a half mile before dying again. (I always end up pushing it back to my house.
Carb has this sucking noise whenever I give it gas

Here is what I have done:
Oil change (10w40)
Valve adjustment (.002 intake .004 exhaust)
Braided silicone hose on secondary air injection (Factory one burst)
Continually have tried adjusting the carb (fuel/air screw)
Took carb apart and inspected everything (105 main jet, idle jet did not have a number on it?)
Put 1 then 2 then 3 washers under the needle (this helped with cold start but still died on me!)
I even got pissed off and bought a brand new pz30 carb.... same thing!

Any help would be greatly appreciated.

Attachment 11666

[Bob form NV]

chruk bashre, I finally got around to taking off the air injector and adjusted the valves. The valves were dead tight. Removing the injector has made a big difference. Reduced backfire and low growl on decel. A definite do if you ask me.

Bikes stalling sounds like fuel restrictions, plugged filters or carb jets would be my first go to.

[birdmanajcarson]

Sounds like a partially blocked tank petcock or the fuel tank is vacuum locking.Next time it happens,open the fuel cap and ride on.If every thing runs properly, take apart the fuel tank cap and clean all the little holes.Do you have a fuel filter?If so,bypass it an see if it runs better.Paper element fuel filters can restrict flow on gravity feed fuel system like motorcycles.

Do you know what this little nipple thing is on the bottom of my tank? I'm guessing it is some type of vent?

uploadfromtaptalk1369688985161.jpg

[ben2go]

Do you know what this little nipple thing is on the bottom of my tank? I'm guessing it is some type of vent?

uploadfromtaptalk1369688985161.jpg

I haven't seen that before.Maybe someone else can chime in.It could be a vent.

[axa]

Do you know what this little nipple thing is on the bottom of my tank? I'm guessing it is some type of vent?

uploadfromtaptalk1369688985161.jpg

When I first saw mine I figured it was the tank overflow.
Sort of like a modern car having the EVAP path with a line running from the tank to the charcoal canister in order to catch gas that might otherwise over flow a full tank when it expanded on a hot day...
A car then purges it upon it's next use with opening of a solenoid valve and vacuum from the engine. I figured ours just dumps it out (on to the engine of all places) through that port.
Am I even close? Anyone??

That said, if that was right, it wouldn't explain why I needed to wrap a cloth around the gas cap when parked. As others use a fluffy hair tie, i have noticed gas coming up from around the cap... that port should relive any pressure.
Really sounds like I may be suffocating my fuel flow as this is where the tank should be venting...

Gunna try removing the cap next time I begin to stall.

[ben2go]

Another thing to check is spark.Take a spare spark plug on a ride.When it quits running,pull the plug wire and put the spare plug on.Ground the plug on the engine and start it while looking to see if the spark plug is producing a bright blue spark.no spark could probably be a bad coil or pick up.

[freezerboy]

I haven't seen that before.Maybe someone else can chime in.It could be a vent.

my 2010 tank does not have that.

[birdmove]

Seems that they are dropping the original bobber this thread is about. They have 2 new ones for more money. The only difference I see is different handlebars and tanks.

[axa]

Seems that they are dropping the original bobber this thread is about. They have 2 new ones for more money. The only difference I see is different handlebars and tanks.

So I wouldn't say it like that... Id say that they are fixing the leaky tank issue, and offering a new front end style. In fact they now offer 2 models, one is the original front end

A new model year is all.

[birdmove]

Well, I'm reading my way through this whole thread. I was aware of the tank leak issue. And I didn't care for the original handlebars much. I'm at the point where Gardo sent his Dong Fang back due to not being able to license it in his state. Gat a ways to go. I assume they got that problem taken care of. I also noticed this bike doesn't have a lick starter. That's too bad.