Dong Fang DF 250 RTB Bobber Information

**barnone** · 09-05-2014, 05:43 PM

Originally Posted by booi10

barnone .... yes mine is 45 T ,,,, so how do you which one to choose if our make of bike is not listed ?? I take it the engine a such are a copy of something ?? I don't think it would be worth swapping the engine for 250 you would be better changing the bike or up to least 450cc,, thanks very much for help you sound very knowlagable and its the first time I have used a forum .... so happy days

You should change out the rear sprocket if your first gear is used up when you cross an intersection. Maybe like the one I suggested off UK Ebay ASSUMING your rear wheel is the same as ours which it probably is.

Like axa said we think you need a JTR279.xx. xx is the number of teeth. For example JTR279.35 is a 35 tooth rear sprocket.

The DF250RTB engine is sort of a copy of the Honda CB125 engine and is called 167FMM.

I do think it would be worth swapping the engine out for a air cooled over head cam full 250cc engine that is a copy of the CB250 engine. Probably could gain about a 50% increase in HP. Should be an easy swap. Going to any thing else gets complicated.

**bowtiewagon** · 09-06-2014, 01:33 PM

Well I did it, hit the 12,000 mile mark. landed @ 12,006 when i parked her in the garage last night. Purrin like a kitten still.

Now,the tank is weird. I was going for that non paint brushed steel look.Hit it with an adhesive clear, then cleared it. But for some reason it seems that under the clear coat, it is rusting? Oxidizing? something. Not sure why. But it looks cool to me, and I have had quite a few compliments on the tank, and people asking me how I did it. Honestly I do not knwo how it happened, but I tell them it is a trade secret. makes me look smarter.. :)
Oh, and yeah she needs to be washed, but it has been raining on and off here, and i ride anyway. Thanks for looking.

**barnone** · 09-06-2014, 02:01 PM

Bow,
Looking real good. That tank is perfect.

**ben2go** · 09-06-2014, 11:50 PM

I saw a DF bobber going through downtown Hendersonville,NC today.All I got was a quick glimpse of the bike and rider.Looked like a younger guy may mid 20's at the oldest.I was a few cars back waiting to turn left on hwy 64 toward Horse Shoe and Etowah.Is that any of you guys?

**axa** · 09-07-2014, 07:20 AM

Originally Posted by bowtiewagon

Now,the tank is weird. I was going for that non paint brushed steel look.Hit it with an adhesive clear, then cleared it. But for some reason it seems that under the clear coat, it is rusting? Oxidizing?

well it's is certainly oxidizing, rustng, same thing...
so what the heck is an "adhesive clear"
I'd guesstimate whatever that was is a water based whatever and thus the oxidation.

anyway I think it's really cool, I can see a frame, tank and matching fenders done like that.

**bowtiewagon** · 09-08-2014, 12:42 PM

Adhesive clear is a prep coat (automotive paint) you can get at Autozone, to prep the metal o the paint will stick. It is basically a clear primer with an adhesive in it. I wanted that metal look, but was not expecting this. It does look cool, but I hope it does not make the tank bad after time. That would suck.

**axa** · 09-08-2014, 04:49 PM

Originally Posted by bowtiewagon

Adhesive clear is a prep coat (automotive paint) you can get at Autozone, to prep the metal o the paint will stick. It is basically a clear primer with an adhesive in it. I wanted that metal look, but was not expecting this. It does look cool, but I hope it does not make the tank bad after time. That would suck.

that does seem odd. i wouldn't imagine a proper product would do that. even if they expected you to paint it over an opaque color.
i dont think surface rust, like you have now, is damaging. what you want to look out for is if the oxidation continues then starts pitting, at that point its eating into the metal and thinning the walls. so see what happens if it starts to get worse, darker, and bumpy.

odd indeed.

**Crelow** · 09-08-2014, 05:55 PM

I have a question for ya. Did you tap into frame or did you weld in nuts? I have to get my tank done, I've had it a year now and has been pushed to back burner. Just bought a Tap set but not sure if it will damage the integrity of the frame.

**bowtiewagon** · 09-08-2014, 07:35 PM

I tapped the frame. used 1/4-20 at first then went bigger cause the 1/4-20 stripped on me. Too small. I am seeing how well these work. I may have to get nuts welded on later. so far so good,I check after every ride. I used some large bushings to fit in bewtween the tank and the frame to sit on for cushion.

**axa** · 09-09-2014, 02:37 AM

i think bow used some sort of bushing to take the load off of the fastener.
id recommend it, and as large as possible. Id use a larger flange headed bolt with perhaps even a washer to support the larger bushing.
And for that top half, my bushing might be some sort of rubberized material hollowed out to hug the tank tab, and flat on top to span the washer...

And when you tap, because of the relatively thin wall, you would do well with a higher pitch count while not going too large on diameter to weaken the frame itself... a 1/4 seems a reasonable diameter, but that has a fine thread of 28 to conciser.
And the hole drilled might be on the smaller size, usually that for softer materials, in the case of a 1/4 tap, use a 3/16 tap, slowly make your threads.

That said a pair of quarter inch tapped holes are marginal mounts at best, hopefully a good set of bushings will prove good enough... id weld it if you have the choice, you can put a bolt in after anyway cuz it looks kind of cool.