Dong Fang DF 250 RTB Bobber Information

**barnone** · 06-14-2014, 11:05 AM

[QUOTE=DanDaMan;69744
so u did get another 1 Barnone ? awesome[/QUOTE]
Yep, bought a 2012 last year.

**Roadkill** · 06-14-2014, 11:56 AM

I do thank you for your response. Several owners have removed that system and capped the plate. I removed the system but just plugged the fitting and replaced the air filter. That plug came loose. This is a miss that is present idle to max. Motor responds great to the throttle and pulls well, it just has a miss at whatever RPM I hold her at. Seemed like a spark issue , but I've replaced CDI, coil and and sparkplug. Plug is gapped to .003.

Recapping that emissions and retuning the carb fixed every issue but the miss. I did the leak test for the carb manifold area and checked the header bolts at the exhaust also. I'm gonna set the valves today.

**Roadkill** · 06-14-2014, 02:48 PM

Valves are adjusted with no change to the miss. They were very tight. She is very rideable and I've read the plug and adjusted the carb so I'm sorta confident that I'm not doing any damage by riding her, so ride I will til I'm ready to send her to a shop.

**barnone** · 06-14-2014, 06:15 PM

Originally Posted by Roadkill

I do thank you for your response. Several owners have removed that system and capped the plate. I removed the system but just plugged the fitting and replaced the air filter. That plug came loose. This is a miss that is present idle to max. Motor responds great to the throttle and pulls well, it just has a miss at whatever RPM I hold her at. Seemed like a spark issue , but I've replaced CDI, coil and and sparkplug. Plug is gapped to .003.

Recapping that emissions and retuning the carb fixed every issue but the miss. I did the leak test for the carb manifold area and checked the header bolts at the exhaust also. I'm gonna set the valves today.

So you have a cap on the port on the intake manifold and a plate on the port on the cylinder?

This miss that you have is constant over the RPM range?

**Roadkill** · 06-14-2014, 06:36 PM

I do indeed. Both the block and intake manifold are capped. Throttles up smoothly and good power. Just has that miss at all RPM. Gets a little better at the top end. I have also changed the air filter to one of about the same size but without the emissions input. I have tried:

CDI, coil, plug, carb tune, starter fluid air leak test, valve adjust, fuel filter, pull the gas cap to make sure it's not a vent issue. Plug is tan and gapped to .0030. Bike starts easily with choke when cold and except for the miss runs well after 5 min warm-up. I think that with carb not running lean, and the valves adjusted, I've checked things which cause damage to the engine so I'll just put a few miles on her and see what happens?

My background is not mechanical, so I think I've exhausted all of my limited skills. I have ordered a in-line spark tester and a compression guage mostly because any job worth doing is worth buying a new tool.

**birdmove** · 06-14-2014, 06:53 PM

Is this an actual miss, or is it more of a pop? On a single, if you have a miss, it's major, since you don't have any more cylinders to keep the engine spinning. Sometimes an engine that's slightly rich or lean, can have a minor pop. But you say your plug is tan, or brownish? A richness can cause some raw gas to collect in the exhaust pipe, and then can ignite, maybe causing a pop. Suzuki Savage/S40's tend to produce a loud backfire when they are shut off due to a lean mixture. But, yet, they run fine. This is an interesting one.

**barnone** · 06-14-2014, 06:54 PM

Not much left to fix the miss.
Could you do an audio and video of the miss at different RPM? Maybe somebody here can help if they hear the miss.

**Roadkill** · 06-14-2014, 06:59 PM

I do thank all for the input! I'm sure that a good mach could figure it out quickly with the bike in front of him. It can be very hard to solve the unusual problems long distance - especially when working with a layman. I will try to get a video this week-end.

**birdmove** · 06-14-2014, 08:14 PM

Hang in there. At least, it sounds like you are able to ride it.

**Roadkill** · 06-14-2014, 09:23 PM

Thank-you birdmove. It is a miss, not a backfire. Had both but all of the things I've done have cleaned her up a great deal so all that's left is the miss. Wish I had a scope so I could look at the trigger pulse coming off the stator. I'm trying hard to find my "tar pit" in the next 3 months or so and retire. I'll have lots of time to play and learn then.