Dong Fang DF 250 RTB Bobber Information

**ben2go** · 03-07-2013, 02:48 AM

Originally Posted by Crelow

Thank god I can rely on the forum! It just reminds me how dumb I am at times when I forget things.

I managed to ride a few miles today and pickup a part from the auto parts store. And since I finally fixed my daily driver I decied to do the smog mod. I cut the sheet metal placed it with hi temp sealent and ground down the back of the plate were the tube stuck out. When that was all done moved the ignition and while moving the tank I shut off the gas. Afterwards I did go through and checked the clips and re-attached everything. Then after everything was put back together I started the engine. Because it was cold I choked. Then put to the second choke setting and got what I call back fire but white smoke coming from the air filter. I get it to run seconds at the time And continue attempting to starting killing the battery. In the end I killed the battery and couldn't get it to stay running. So I decieded to put it away.

I read Googbar's post about the tank when I came in and the light shined over head. I ran out to the shed and opened the gas valve. She stated right up! ;-) my dumb moment. But I think next week ill check the valve clearance ans I don't under stand why she still back fires.

Attachment 10329
Attachment 10330

Are you getting a back fire through the carb or after fire through the exhaust?Through the exhaust would indicate a lean condition caused by removing the emissions tube.That will required a rejet.Crap blocking an orifice in the carb would cause backfiring through carb.Also sticky intake or tight intake valve can cause it along with ignition timing problems.

**freezerboy** · 03-07-2013, 03:22 AM

Crelow is your bike a Nov or December 2010 build? If u got the Nov model, did you rejet your carb on it?

**Bob form NV** · 03-07-2013, 03:58 AM

I'm thinking maybe one of these.

http://www.roguemotorsportz.com/i601...Fag7MgodpAoAPA

**Crelow** · 03-07-2013, 04:50 AM

Ok this is what I can tell you. This has happend since day 2. The day I went to pick it up the guy had the bike warmed up. I think it happens less when the bike is warmed up. Not 100% certain. I think it's either back fire or exhaust. A white puff appears from the air filter not certain what that is. This has happend before the smog mod. But I'm loving the fact that the popping has ended and I would imaginge the noise comming form that contraption.

The bike build date shows DEC 2010

**Bob form NV** · 03-07-2013, 05:40 AM

I thought removing the emission tube and the pump was supposed to help eliminate the lean condition and fix the jet problem?

**Goodbar** · 03-07-2013, 06:08 AM

Hey everyone, Ill throw in my 2 cents on a few of the debates going on air filters and popping or backfiring thru the carb. Back firing thru the carb on these things is a bit of a problem just until warmed up but it can be minimized to (almost) zero by making sure of the following: all have to be done:
A correct jets so not too lean 105 main and 42 idle jet,at least a 105 all the way to 110 108 is what I run
Warm the bike to temp, take a sharpie and mark the carb adjustment screws and threads so you know were it is now.
B Carb adjusted ( very sensitive to slightest turn of the air fuel screw the one facing the manifold) use the screw driver bit from a interchangeable screw driver and rev until smooth and popping out of the carb goes away or is at the least. tiny adjustments make huge differences on this carb and bike engine, tweak till it revs fast and smooth.
C adjust the Low speed carb or idle speed) last so it runs not too slow or too fast/ sensitive also
Remember that just a tiny turn one way or the other makes a huge change on these things once it gets into the sweet spot.
Whats odd about carb backfiring as it can be from too lean or too rich but if its too lean one cannot get rid of it. In fact this carb back firing could damage your engine as it stops the crank and kills the engine, so address it. Also a # 4 washer under the needle later on will smooth it out even more as it will just speed up throttle response. Really this carb is a breeze to work on as it’s so simple that beginners should not be afraid to tackle anything on it. If you can get a friend to give you moral support and lend a hand.
D take it for a ride if you can and you can tweak it even a bit more. Put a tiny drop of lock tite on the Carb adjust screw when you love the ways it runs
Yes the Valves are also no doubt all over the map in adjustment and do this after 500 miles at least. if you feel performance is lacking badly otherwise wait till break in is complete.
These little but great engines are really tight when new and will smooth out greatly with every 1000 miles.
The wire screen air filters all suck, no pun, they should be lightly oiled but for total protection of dust and silt I recommend a 42 MM KN paper type it will breath good and won’t let any particles past, down side is really can’t be washed out completely just blown off and wiped with a stiff brush and they are useless in the rain.
So it’s all a compromise. The carb jets mainly the low speed jet has a almost microscopic hole in it and will clog fast from our crappy gas, The good thing is the bike wont idle or start if its plugged. Get a 5 buck jet cleaning kit off ebay. The smallest wire in that kit barely fits thru the slow speed jet but works. It takes nothing at all to plug jets half way. I use aircraft gas 91 octane lead free you can buy at any county airport for 4.50 a gal. get 5 gallons if you don’t ride Much and add fuel stabilizer. Also add a clear proper fuel filter with a 1/4 " ends on it. This will keep your bike dependable/ change it once a year as they are only 3 bucks.
Anyhow the link that freezer boy has up for a air filter is the one I run now as it is a finer mesh than stock
a very, very light oiling with 10w 40 on a rag is all one needs on it to keep 99 percent of the crud out but offers no Guarantee.
I wish someone mfg a finer mesh wire type but there is none available. adding a small oiled foam piece in there may help but a slight carb adjustment may be needed to decrease the fuel mixture also.
Just remember the carb jets blow stuff out on their own and the main reason they get clogged is not dust and dirt but fuel that has turned into varnish and crystallized.

Anyhow sorry for the long post/ Ill throw some mod picts up in a minute and the pict of the bracket all owners of the DF need to check to make sure the speedo cable is secured because its white block connector will catch the turn signal wires and they are connected to the main harness and will rip wires right and left and could even be a fire hazard.

By removing the smog crap one is really not doing a ton but giving the bike fresh air VS air that has VOCs which one could argue is unburned gas vapor that could make the bike richer in the gas dept but lower in the O2 dept. Either way taking it off needs a carb adjustment tweak, a tiny tweak. Once that tweak is made your bike should run better. Lots of factors here but that really is the fun part of dialing it in so its yours and then you really feel like you own it and control it. I also worry that your caps some of you have made may be leaking a bit. bI would really use thick gauge steel and seal it with a silicone sheet gasket and tighten it good. Lots of pressure in there one does not want to lose.

**Crelow** · 03-07-2013, 06:19 AM

Originally Posted by Goodbar

Hey everyone, Ill throw in my 2 cents on a few of the debates going on air filters and popping or backfiring thru the carb. Back firing thru the carb on these things is a bit of a problem just until warmed up but it can be minimized to (almost) zero by making sure of the following: all have to be done:
A correct jets so not too lean 105 main and 42 idle jet,at least a 105 all the way to 110 108 is what I run
Warm the bike to temp, take a sharpie and mark the carb adjustment screws and threads so you know were it is now.
B Carb adjusted ( very sensitive to slightest turn of the air fuel screw the one facing the manifold) use the screw driver bit from a interchangeable screw driver and rev until smooth and popping out of the carb goes away or is at the least. tiny adjustments make huge differences on this carb and bike engine, tweak till it revs fast and smooth.
C adjust the Low speed carb or idle speed) last so it runs not too slow or too fast/ sensitive also
Remember that just a tiny turn one way or the other makes a huge change on these things once it gets into the sweet spot.
Whats odd about carb backfiring as it can be from too lean or too rich but if its too lean one cannot get rid of it. In fact this carb back firing could damage your engine as it stops the crank and kills the engine, so address it. Also a # 4 washer under the needle later on will smooth it out even more as it will just speed up throttle response. Really this carb is a breeze to work on as it’s so simple that beginners should not be afraid to tackle anything on it. If you can get a friend to give you moral support and lend a hand.
D take it for a ride if you can and you can tweak it even a bit more. Put a tiny drop of lock tite on the Carb adjust screw when you love the ways it runs
Yes the Valves are also no doubt all over the map in adjustment and do this after 500 miles at least. if you feel performance is lacking badly otherwise wait till break in is complete.
These little but great engines are really tight when new and will smooth out greatly with every 1000 miles.
The wire screen air filters all suck, no pun, they should be lightly oiled but for total protection of dust and silt I recommend a 42 MM KN paper type it will breath good and won’t let any particles past, down side is really can’t be washed out completely just blown off and wiped with a stiff brush and they are useless in the rain.
So it’s all a compromise. The carb jets mainly the low speed jet has a almost microscopic hole in it and will clog fast from our crappy gas, The good thing is the bike wont idle or start if its plugged. Get a 5 buck jet cleaning kit off ebay. The smallest wire in that kit barely fits thru the slow speed jet but works. It takes nothing at all to plug jets half way. I use aircraft gas 91 octane lead free you can buy at any county airport for 4.50 a gal. get 5 gallons if you don’t ride Much and add fuel stabilizer. Also add a clear proper fuel filter with a 1/4 " ends on it. This will keep your bike dependable/ change it once a year as they are only 3 bucks.
Anyhow the link that freezer boy has up for a air filter is the one I run now as it is a finer mesh than stock
a very, very light oiling with 10w 40 on a rag is all one needs on it to keep 99 percent of the crud out but offers no Guarantee.
I wish someone mfg a finer mesh wire type but there is none available. adding a small oiled foam piece in there may help but a slight carb adjustment may be needed to decrease the fuel mixture also.
Just remember the carb jets blow stuff out on their own and the main reason they get clogged is not dust and dirt but fuel that has turned into varnish and crystallized.

Anyhow sorry for the long post/ Ill throw some mod picts up in a minute and the pict of the bracket all owners of the DF need to check to make sure the speedo cable is secured because its white block connector will catch the turn signal wires and they are connected to the main harness and will rip wires right and left and could even be a fire hazard.

By removing the smog crap one is really not doing a ton but giving the bike fresh air VS air that has VOCs which one could argue is unburned gas vapor that could make the bike richer in the gas dept but lower in the O2 dept. Either way taking it off needs a carb adjustment tweak, a tiny tweak. Once that tweak is made your bike should run better. Lots of factors here but that really is the fun part of dialing it in so its yours and then you really feel like you own it and control it. I also worry that your caps you may be leaking a bit . I would really use thick gauge steel and seal it with a silicone sheet gasket and tighten it good. Lots of pressure in there one does not want to lose.

Thank you so much for the info.

**Crelow** · 03-07-2013, 06:26 AM

Ill post a vid as soon as I can.

**Goodbar** · 03-07-2013, 06:27 AM

Black Df with Barrel springs installed using seat bracket.jpg Make sure you have this bracket installed on speedo cable I made this one to prevent wires teari.jpg Seat bracket Cu of clevis pins threaded into bracket.jpg seat bracket detail IMG_3427.jpg Seat Bracket that fits under seat using original bolts fits between the y bracket on original se.jpg

Sorry the pictures got out of order The important one is the speedo bracket.
I made this one as his was missing and really caused havoc with all his wiring.
double check this bracket is there and tight and tightened on the thick part of the speedo cable not the thin part of it.
The other picts is a neat way to add old school look springs correctly to your original seat as this bracket fits under the origianl seat and uses the bolts that are allready on the seat/ no alterations needed. Plus the 2 extra springs make the bike look way better and more old school and the mono spring is still there for even more support and spring action.
Then Skullworkz wifes shop can make you a custom seat cover loaded with gel or foam in anything you could dream of as they have the seat pattern ready to go, I am going to order a cooler looking cover soon from them, mine is pretty plain jane. Their work is amazing! The link is on forum.

Bob ,Hopefully the pict is clear enough on the bracket!

**Goodbar** · 03-07-2013, 06:58 AM

Your welcome Crelow...ever wonder why one forgets how to spell when typing in a forum? Gee sorry for all the typosss.
Your carb back firing is really a routine adjustment/ no worries/ mine was so bad it was like a grenade launcher when I picked up. In fact so bad it killed the engine every time it burped thru the carb. Now she runs smooth as silk. Remember were really doing our own Pre Delivery Inspection on these bikes. If it was a Yamaha dealer they would adjust all this stuff before you recieved it but they are 5K. You saved money and this is one of the reasons, you are now your own dealer mechanic paying yourself to get it running perfect. In the long run ownership will be so much more satisfying.
POP POP BANG POP
The occasional pop out of the exhaust just lets me know shes alive. It for sure will make people duck for cover and call 911

Bob, The bike rally sound huge for the area, yeh it will get a ton of attention.
guys with 30K bikes will be going hmmm. Throw some custom gold or silver vinyl laminated symbols or name on there for a tank badges and it will really keep them guessing. If anyone needs something just go to fast signs and bring your art, but have them laminated so they will last. I think it costs like 20bucks for 2 ea.
TIP If you get some Nu finish scratch doctor and a clean 100percent cotton rag and you rub the paint all out with a bit of pressure and elbow grease, the paint on these bikes gets super glossy as the clear coat is so thick. I did all the paint on the tank and fenders and even the frame and yes the engine and it adds a permanent shine that will really wow, and it is even amazing to touch. Try a patch if you dont believe me. This stuff is the finest of fine rubbing compounds and It really is night and day difference to those that like shiny and glossy and want there bike to look more detailed....I like Shiny

Its another 7 buck mod that will keep you outa the wifes hair for 1 more evening
df250 rtb IMG_3217 forum.jpg