Dong Fang DF 250 RTB Bobber Information

can anyone tell me what size main jet the 2012 bikes come with?
barone, so what size jets are you up to so far?


Ive always noticed studdering at my very top end and suspected that the main jet could be sized up, but when i tried slightly closing up the choke, it immediately got worse, indicating perhaps it could use more air...

plug reads fine so I think for the most part its a good mix, just not at those rare long straight or downhill top end moments...

so it would be nice to know what size we are starting with here

how many of you have had to replace the stock horn , and how many times. My issue Is not that the horn fails to work, it is that the bracket it is attached to keeps breaking. I have had to replace it twice now. seems that it rattles so bad that it eventually just breaks. I am in the market for replacements and was thinking of going with a louder style horn set.

By the way.. I am up to 9907 miles as of last nights ride. Gonna do the Chinese fire drill when it hits 10,000. Plus take pictures.

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Originally Posted by bowtiewagon

how many of you have had to replace the stock horn , and how many times. My issue Is not that the horn fails to work, it is that the bracket it is attached to keeps breaking. I have had to replace it twice now. seems that it rattles so bad that it eventually just breaks. I am in the market for replacements and was thinking of going with a louder style horn set.

By the way.. I am up to 9907 miles as of last nights ride. Gonna do the Chinese fire drill when it hits 10,000. Plus take pictures.

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so what about just bolting a thicker bracket. or a rubberized bracket...
but if you want a new style horn then do that, i like the sound of my high/low over the button. But if you get a cheap pair as i did, don't expect a huge difference. Theres a differacne, but its just not huge as i thought it would be.

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Originally Posted by axa

can anyone tell me what size main jet the 2012 bikes come with?
barone, so what size jets are you up to so far?


Ive always noticed studdering at my very top end and suspected that the main jet could be sized up, but when i tried slightly closing up the choke, it immediately got worse, indicating perhaps it could use more air...

plug reads fine so I think for the most part its a good mix, just not at those rare long straight or downhill top end moments...

so it would be nice to know what size we are starting with here

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My 2012 came with a 105 main and unmarked low speed. Tried a 108 and think it was still lean. Just put in a 120 main and 42 low speed but haven't tried yet because it is raining here.

I drilled out the catalytic converter (kinda loud now) and that helped the top end performance somewhat so maybe the 120 will be good.
I'm over 300 miles so I can run her out now.

She pulls pretty good up to about 6000 RPM then I start getting that hesitation (stuttering) at wide open too so maybe a bigger main will help. 6000 RPM equals about 60 MPH indicated with my gearing.

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Originally Posted by barnone

My 2012 came with a 105 main and unmarked low speed. Tried a 108 and think it was still lean. Just put in a 120 main and 42 low speed but haven't tried yet because it is raining here.

I drilled out the catalytic converter (kinda loud now) and that helped the top end performance somewhat so maybe the 120 will be good.
I'm over 300 miles so I can run her out now.

She pulls pretty good up to about 6000 RPM then I start getting that hesitation (stuttering) at wide open too so maybe a bigger main will help. 6000 RPM equals about 60 MPH indicated with my gearing.

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I have the same symptoms.
With my new tachometer, I also see it top out just about 6k and 60mph indicated.

Be sure to post about your 120 jet.
Are there model numbers for these main jets i can look for?

it could simply be valve float and not hesitation , and I slapped on a CAR HORN I got off the shelf in Orilies autoparts

6k rpms is 68 indicated at the top of 4th gear for my sprocket/ratio set up

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Originally Posted by DanDaMan

it could simply be valve float and not hesitation , and I slapped on a CAR HORN I got off the shelf in Orilies autoparts

6k rpms is 68 indicated at the top of 4th gear for my sprocket/ratio set up

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I'd like to know what RPM you are turning when you are running 80 MPH. And have you checked the speed with a GPS?

Max Horsepower: 17@8000rpm :lol8:

Max Horsepower: 17@8000rpm

that's INDICATED , and at 70 indicated , im actually goin 63 , 10% off

and as I said be4 , believe its about 6k rpms then it valve floats

gearing for 85 like I did , might be pushing it because 5th has no umph when its HOT out , ill shift to 5th at 65 or so and cruise at 70-75 indicated

its funny with everyone saying its not made for it/don't try it , but I got this bike PURELY for use as a highway bike

Quote:

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Originally Posted by axa

I have the same symptoms.
With my new tachometer, I also see it top out just about 6k and 60mph indicated.

Be sure to post about your 120 jet.
Are there model numbers for these main jets i can look for?

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Main Jets
http://www.jetsrus.com/a_jets_by_car...4-36_main.html
Slow Jets
http://www.jetsrus.com/a_jets_by_car...low_26-xxx.htm

my 2010 manual states 14 @6500 rpms as standard power and 11 @ 6500 rpm max power , but max torq of 16.5 @ 5500 rpm

I stretched my gears so long I cruise at 73 ish indicated at about 5000 rpm's

aim for 4500-5500 as your powerband , if you try to use the 6k listed you will be floating valves and never possibly drag more speed from it

if I wer U , I would stretch gears so I shift from 4th to 5th at 55-60 (mines set for 68) , even if you never see the top of 5th it gives you much more relaxed rpm's when cruising nearer to highway speeds