Dong Fang DF 250 RTB Bobber Information

**drgnsghost** · 06-02-2014, 01:18 AM

So this is page 500. I've read at least 350 if these pages, with a pretty solid collection of bookmarks. I've had a few victories with the things learned, but always seem to find a way NOT to enjoy my bike. I can only get 30mph max on my df, I changed to a 38t and speedometer marks 35mph now. Not sure if that's actual gain of speed though. I opened up the carburetor to clean and inspect my jets. I have a Dec 2010 model, so jets are 105/40. I figured, well at least I know I can easily install new bigger jets. I put the bike back together, she has a hard time starting but after a while she cranks up. I get ready to go on a slow cruise the next day, she cranks right up and by the time I got my helmet on she died out. Now she won't start at all.
There's fuel going into the carb just fine. But when I squeeze the accelerator with no air filter on fuel does not squirt out anywhere except for the sides of the carb. I've now taken the carb apart several times to check if I missed something, didn't tighten all the screws, etc. She's just not starting.

**ben2go** · 06-02-2014, 02:31 AM

Originally Posted by drgnsghost

So this is page 500. I've read at least 350 if these pages, with a pretty solid collection of bookmarks. I've had a few victories with the things learned, but always seem to find a way NOT to enjoy my bike. I can only get 30mph max on my df, I changed to a 38t and speedometer marks 35mph now. Not sure if that's actual gain of speed though. I opened up the carburetor to clean and inspect my jets. I have a Dec 2010 model, so jets are 105/40. I figured, well at least I know I can easily install new bigger jets. I put the bike back together, she has a hard time starting but after a while she cranks up. I get ready to go on a slow cruise the next day, she cranks right up and by the time I got my helmet on she died out. Now she won't start at all.
There's fuel going into the carb just fine. But when I squeeze the accelerator with no air filter on fuel does not squirt out anywhere except for the sides of the carb. I've now taken the carb apart several times to check if I missed something, didn't tighten all the screws, etc. She's just not starting.

These are CV carbs.They don't squirt gas like an automotive carb.If there is no vacuum from the engine running,there's no fuel being sucked trough the carb.It's starting to sound like your valves need to be adjusted or the valve timing chain has jumped a tooth.

**drgnsghost** · 06-02-2014, 02:36 AM

Wish I knew what any of that stuff was. Lol. I'm new to bikes which may explain the hard time I'm having. I posted some videos if it helps. Watch "Df carb" on YouTube
Df carb: http://youtu.be/Gz7MyMU1IUkWatch "Starting bike" on YouTube
Starting bike: http://youtu.be/ukbF5Y805aM

**drgnsghost** · 06-02-2014, 02:42 AM

I'm guessing this is what might need to be done?http://www.mychinamoto.com/forums/sh...justing+valves

**barnone** · 06-02-2014, 11:32 AM

There is an accelerator pump on the DF carb that will squirt gas when you twist the throttle.

Valve adjustment
https://docs.google.com/file/d/0ByFv.../edit?hl=en_US

Carb tuning Note DF carb is PZ30 like the PZ26
http://wem.walbro.com/distributors/s...CAEBURETOR.pdf

**ben2go** · 06-02-2014, 12:57 PM

Originally Posted by barnone

There is an accelerator pump on the DF carb that will squirt gas when you twist the throttle.

Valve adjustment
https://docs.google.com/file/d/0ByFv.../edit?hl=en_US

Carb tuning Note DF carb is PZ30 like the PZ26
http://wem.walbro.com/distributors/s...CAEBURETOR.pdf

Oh yeah.I forgot these have pumper carbs not standard CV carbs.

**bowtiewagon** · 06-02-2014, 11:41 PM

just wondering guys, can the transmission be a factor in the bike not starting? I mean The starter rotates both reduction gears, but I cannot seem to get the motor itself to rotate?. I pulled the intake off I can see directly into the head and the intake valve.When i turn the crank by hand the valve moves, but when i try to do it with the starter nothing moves. I noticed in the parts diagrams there is a gear called the Starting Ratchet. Would that be an issue? I am at my wits end here with why it will not start.
Gets plenty of gas, has spark valves work , not frozen, hand turns no problem, will not turn with starter. Also my next question, can i take the crankcase cover off and not disrupt anything inside, or is it all connected to the cover?

**ben2go** · 06-03-2014, 04:35 PM

Originally Posted by bowtiewagon

just wondering guys, can the transmission be a factor in the bike not starting? I mean The starter rotates both reduction gears, but I cannot seem to get the motor itself to rotate?. I pulled the intake off I can see directly into the head and the intake valve.When i turn the crank by hand the valve moves, but when i try to do it with the starter nothing moves. I noticed in the parts diagrams there is a gear called the Starting Ratchet. Would that be an issue? I am at my wits end here with why it will not start.
Gets plenty of gas, has spark valves work , not frozen, hand turns no problem, will not turn with starter. Also my next question, can i take the crankcase cover off and not disrupt anything inside, or is it all connected to the cover?

Sounds like the starter clutch which is referred to as a starting ratchet.I'm not sure how they work in these little motors.I've had hem give up in bigger Jap bikes.

**bowtiewagon** · 06-03-2014, 07:24 PM

Originally Posted by ben2go

Sounds like the starter clutch which is referred to as a starting ratchet.I'm not sure how they work in these little motors.I've had hem give up in bigger Jap bikes.

O.K> so next question is, can the crankcase houseing/transmission cover come off without disrupting anything...like parts falling out.I have never taken anything that far apart on this bike, and do not want like a lump of parts on the floor just cause I took the cover off.

**drgnsghost** · 06-03-2014, 10:03 PM

Looks like my battery just needed charging. Soon as I charged and reconnected the battery, she started right up. Although now the engine is revving extremely high. Turning the air/fuel mix screws didn't help, so I'll be doing more reading on how to adjust the valves like you guys said. Most of the posts I've read say it's pretty easy, just nervous cause I'm new to bikes and mechanics.
Thanks for the help!