Dong Fang DF 250 RTB Bobber Information

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Originally Posted by GonzoX

I agree, the p trap looks a lot better and doesnt look like it will get in your way while riding. And with the stock filter with no filter media on the tip end I think it will get the air ram effect at speed.

But Im a type A personality myself and hate the stock filter. To me a filter should do just that, filter the air and keep the crap out of the carb. Dirty carbs are a royal PITA to fix and are hard to diagnose when they cause a problem so Im the kind of guy who wants absolutely clean air going into the carb. That's two things I dont skimp on with any of my vehicles, oil and filter media. One ouce of prevention prevents a pound of pain later.

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though doesn't proper air filter media reap havoc on decent air intake.
idk, I've had dirty carbs on dirt bikes, but never one of my street bikes, I suppose I havnt ridden as long as others.
but on the road bikes, I've always noticed more junk collecting down in through the gas cap hole than collected in or around my air filter. but maybe that is not a fair scientific comparison.
bottom line if a proper filter wouldn't starve this bike I'd have one too.

that said what do you use for a gas filter

Quote:

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Originally Posted by axa

so 1" to not bore out the innards cleanly parrallel to the exhaust inner wall, but rather mutilate the innards with a smaller 1" diameter drill and have at least that large a passage.
would you say that is accurate?

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axa,
Disclaimer: DO NOT attempt this if you do not have the skill to perform this operation. DO NOT come back to me complaining after you have screwed up your muffler. Performing this will increase the noise of the DF exhaust.

Attachment 13093
Note: this drawing is not the exact same as our DF exhaust system but just a typical motorcycle exhaust system.
It is presented as an aid.
The catalytic converter is about at location 211 in the drawing above.
Do not remove the material at 209.


Take a flash light and look up the exhaust pipe and see the catalytic converter in the forward part of the muffler. That catalytic converter impedes the flow of the exhaust gas.

Attachment 13092
Above is an example of the kind of catalytic material you want to remove.

Just remove the catalytic converter material that is in the forward part of the muffler not the muffler sound suppression material. DO THIS AT YOUR OWN RISK.

Quote:

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Originally Posted by axa

you mean you don't wind out each gear so not chance to sputter? or just somehow the condition has gone with the new gearing?

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The gearing change should not prevent the sputtering in the lower gears however I keep the RPM below 6k so don't care. The p trap ram will have no effect at lower speeds but the tube might improve air flow like an air box does. I don't know.

I don't run my vehicles at top RPM.

I believe the gearing is high enough in fifth gear to prevent the sputtering but still allowing a top speed of about 65 MPH indicated. I have not verified the accuracy of the speedometer but the odometer appears to be about right.

Going back and reviewing my post from my 2010 indicated I had a 68 MPH GPS top speed with a 33 tooth rear sprocket so maybe the 35 you have is just fine. I'm at 108 main, 42 slow, 2 shims under the needle (3 M washers) and at 2k to 5k altitude.

Your results will probably VARY.

I fixed the leaking carb issue but just snapping the throttle a few times. I have a 42 slow and a 108 main. It idles smooth but full throttle spudders and breaks up very very bad. I may just go back to the 105 and forget it. I cant get it rev smoothly at all. I will mess with it a bit more. I still think the slow jet is the wrong type even though I matched the serial number for the one that was listed on here as being a good replacement

Quote:

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Originally Posted by Bobthebobber

I fixed the leaking carb issue but just snapping the throttle a few times. I have a 42 slow and a 108 main. It idles smooth but full throttle spudders and breaks up very very bad. I may just go back to the 105 and forget it. I cant get it rev smoothly at all. I will mess with it a bit more. I still think the slow jet is the wrong type even though I matched the serial number for the one that was listed on here as being a good replacement

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The low speed is a newer type and works well in my 2012 DF
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axa,
Attachment 13096
axa,
Photo of the hole saw and extension that I bought off Amazon years ago that I used it to remove the catalytic converter on my 2010 and my 2012 DFs. Worked for me but you are on your own.

GonzoX,
Also the dipstick from my 2012 DF. Plenty available on Ebay and Amazon if you search for atv , dirtbike, motorcycle etc dipstick. Match up the length.

Here is one that looks right but YOU NEED to make sure.
http://www.ebay.com/itm/OIL-DIPSTICK...3e19a6&vxp=mtr

Thanks for all your help Barnone!

My bike starts instantly, runs great, hits 67 mph, 60 to 75 mpg. Should I try to mods like everyone or just leave it? I'm afraid to mess with anything except the idle. It has almost 2K. I bought it locally. They let me test drive it. Only driven a bike once 20 years ago I instantly was hooked!! I also run 100% gasoline (no ethanol) high octane.

Quote:

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Originally Posted by axa

though doesn't proper air filter media reap havoc on decent air intake.
idk, I've had dirty carbs on dirt bikes, but never one of my street bikes, I suppose I havnt ridden as long as others.
but on the road bikes, I've always noticed more junk collecting down in through the gas cap hole than collected in or around my air filter. but maybe that is not a fair scientific comparison.
bottom line if a proper filter wouldn't starve this bike I'd have one too.

that said what do you use for a gas filter

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Stock filter that came with it but that will also be replaced soon. This bike is a work in progress.

Quote:

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Originally Posted by barnone

When I change my oil on the DF I use about 1.2 liters (1200 ccs) of oil and the dip stick and the sight window both show full. Remember to stand the bike upright when you are using the site window. (Also don't screw the dipstick in when checking the oil.)
And I don't know what you mean about "just plug the damn thing up and use the sight glass". You still need to unscrew the cap to put oil in it.
I've had many bikes with just site windows and never blew an engine.

BTW, again for those who have a intact dipstick, don't screw the dipstick in when checking the oil.

I'll measure the dipstick length on my 2012 DF and get back to you.

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Thanks barnone, Im good.

I did a search using the DF250 parts number list and found the correct stick (oil ruler assy) at rocketa.com. Or at least it says it's the correct part. Guess Ill find out.