Dong Fang DF 250 RTB Bobber Information

**barnone** · 09-20-2014, 09:18 PM

axa,
Sounds good. Is 68 indicated GPS or speedometer? True speed?

**axa** · 09-21-2014, 01:24 AM

Originally Posted by barnone

axa,
Sounds good. Is 68 indicated GPS or speedometer? True speed?

it's stock speedometer...
63-64 was the best I ever saw previously, back when I beat the bike hard...
this was on the same stretch road a gradual decline, on the way home from work...

I might have reported earlier but I am now able to hold over 50 on the same road but on the incline on the way to work .

There i recall i used to lose velocity, sometimes to the point in need to down shift, but then being at the red line, so it didn't solve anything.
Getting passed by the garbage truck I think lead me to this search for power.

putting in the 115 main jet now, unfortunately I don't have a 112

**axa** · 09-23-2014, 01:10 PM

Someone has to do me a favor and disconnect their R/R output (the red, black, green wire side) while the bike is running and tell me what readings they get.

Ive now have 2 that both appear to function, or rather malfunction, in the same way so im quite surprised.

Again, from what i understand, the reading should roughly be 12v dc at idle, and then increase as rpm increases, but as your tired of hearing me state, my dc readings decreases as rpm increase..

So, I think i know why, but it would be nice for someone to confirm they get the same results...

It appears that these Rectifier/Regulators do a pretty good job of regulating voltage, but falls short in the way of Rectifying it... Specifically in creating the consistent dc component that is expected.

I bench tested one these placing it on my scope. Fed up to 36V AC pp between 2 of the inputs, that would be normally 1 of the 3 phases from the stator... but what i measured on the output was NOT a half rectified wave at 120° as expected. Rather it was a mirror image of the input, in other words it was also an AC sine wave??
But more importantly, there was apparently very little Reservoir capacitance to smooth (retard voltage roll off) and create the dc component.

I go on to speculate that since little of this rectifying is happening, as the frequency increases, the effect of any reservoir capacitance decreases, even less smoothing, and thus less RMS power...

maybe this is just how the R/R this bike comes with works. Its not to say there is no power is generated, perhaps enough to keep the battery from depleting, but what do i know...

Im suppose i will look into adding a reservoir cap, and see how that helps things...
But honestly this stuff bores me and im tired of it...

Anyone ever try a different model R/R?

**barnone** · 09-23-2014, 01:57 PM

axa,
Where are you measuring the voltage when you disconnect the rectifier? Battery? I'll go take a look at my DF.
# 3 at
http://www.scooterdepot.us/parts_htm..._list.html#f16

**SR.MAILMAN** · 09-23-2014, 02:45 PM

Here is a LONG read that explains the difference between shunt & mosfet R/Rs. Charging System Diagnostics - Rectifier/Regulator Upgrade - Triumph Forum: Triumph Rat Motorcycle Forums
The best one for the 250 would be the Polaris SH775. The price is high though.
You would have to change the connection plugs.
I know that the china bike fans like to keep the price down and the problems you are experiencing are directly related to that goal.
As I remember... the GREEN wire was the reason for the goofy readings you are getting. Perhaps BarNone could explain why it was disconnected in the past.

**axa** · 09-23-2014, 04:04 PM

Originally Posted by barnone

axa,
Where are you measuring the voltage when you disconnect the rectifier? Battery? I'll go take a look at my DF.
# 3 at
http://www.scooterdepot.us/parts_htm..._list.html#f16

if referencing the drawing in that manual, that isnt the R/R they use on the bike at all. At least not my bike...
just yet another thing the DF didnt get right in that manual... oddly enough, each of the parts i specifically needed to know about, ive looked up in that manual and found they were entirely the wrong parts.

So, regarding measurements, since what i want to know about is the output of the rectifier, youll want to disconnect the output of the rectifier.
not much concerned with what the battery puts out...

Real curious what it is putting out for others...

**axa** · 09-23-2014, 04:12 PM

Originally Posted by SR.MAILMAN

Here is a LONG read that explains the difference between shunt & mosfet R/Rs. Charging System Diagnostics - Rectifier/Regulator Upgrade - Triumph Forum: Triumph Rat Motorcycle Forums
The best one for the 250 would be the Polaris SH775. The price is high though.
You would have to change the connection plugs.
I know that the china bike fans like to keep the price down and the problems you are experiencing are directly related to that goal.
As I remember... the GREEN wire was the reason for the goofy readings you are getting. Perhaps BarNone could explain why it was disconnected in the past.

this green wire was disconnected before?!?
yea i cant fathom why there are 3 outputs on this thing.

no doubt cheap Chinese parts, but isn't that the motto of this bike... cheap, now cross ur fingers...

so that thread mentions the mostfets being the cheap ones, but having tested these R/R they seem to have both a forward and reverse diode pair for each of the 3 input nodes...

**barnone** · 09-23-2014, 05:11 PM

I did not disconnect anything as my DF is doing just fine and don't want to screw anything up.
My measurements with a Harbor Freight digital meter and Shorai battery.

Engine off 13.09 volts
Engine idle 13.17 volts
Engine revved up 13.58 volts

**barnone** · 09-23-2014, 05:21 PM

Originally Posted by axa

if referencing the drawing in that manual, that isnt the R/R they use on the bike at all. At least not my bike...
just yet another thing the DF didnt get right in that manual... oddly enough, each of the parts i specifically needed to know about, ive looked up in that manual and found they were entirely the wrong parts.

So, regarding measurements, since what i want to know about is the output of the rectifier, youll want to disconnect the output of the rectifier.
not much concerned with what the battery puts out...

Real curious what it is putting out for others...

axa,

My bad. The parts list I posted was for the 2010.

Should be this one for your DF250RTB-B

http://www.df-motor.com/MLC/Parts%20...TB-B(2014).pdf
page 23

**SR.MAILMAN** · 09-23-2014, 07:25 PM

This is what I was refering to:
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.
An old quote that must be from the 2010 DF model.
At these prices,150cc to 250cc rectifier. I can see why My link to R/Rs would be insulting. I am SORRY I tried to help.
(spending $80.00 on a Bullet-proof R/R & $105.00 for a Shorai battery for My bikes is just the way I roll)
Wrenching for 58 years will do that...