Dong Fang DF 250 RTB Bobber Information

**reporon** · 06-27-2011, 03:44 AM

top speed at close to 70. secondary air injection is for emissions. i have read here that eliminating it gains around 1 hp & makes the motor run slightly cooler.

**Gumpsta** · 06-27-2011, 05:56 AM

Put a 35t sprocket on today. Much better. I've also got a 520hd repair kit I can't use due to barnones
Post. Oh well, I'll use it one day maybe. Jets coming this week. Bike still runs good. Still waiting on MCO from Chad . Really annoying waiting on the paperwork.

**AKAsam** · 06-27-2011, 12:10 PM

Barnone, where did you get the block off plate for the secondary air injection? thanks

**barnone** · 06-27-2011, 12:37 PM

I made the block off plate out of 1/8" aluminum plate using the gasket as a pattern.
The Secondary Air Injection (SAI) pumps air down stream of the exhaust valve to help burn off gas to reduce emissions. Removing it should reduce engine temperature some but should not improve performance.

**barnone** · 06-27-2011, 12:40 PM

call,
I replaced the main jet with a 100. My DF came with a 88 size but others are reporting different sizes so I would look at what is in the carb before ordering jets.
I put a washer under the needle to richen up the mid range.

**AKAsam** · 06-27-2011, 12:41 PM

When i had it open i was getting better performance. I don't know what will happen blocked off.

**barnone** · 06-27-2011, 12:53 PM

Originally Posted by callmebrick

Oh, and what top speeds are y'all getting with your bikes? Can it go at highway speeds?

What do you call highway speeds?

If you are talking 70MPH then these bikes with a 229 cc engine is not going to cut it. Yes you can improve the performance a bit but do you want to be running wide open trying to keep up with traffic. Not me,

IMHO, on the interstate you need at least a 500cc bike. Plus remember these are hard tail bikes so the handling is compromised.

BTW, I am getting PMs from Heist owners that are having problem getting their bikes to run properly with the carb mods that some are doing including the Weaver carb. My advice is to run the stock bike for a while and then do the mods one at a time to see what happens. Don't shotgun a bunch of changes.

**barnone** · 06-27-2011, 12:57 PM

Originally Posted by Gumpsta

Put a 35t sprocket on today. Much better. I've also got a 520hd repair kit I can't use due to barnones
Post. Oh well, I'll use it one day maybe. Jets coming this week. Bike still runs good. Still waiting on MCO from Chad . Really annoying waiting on the paperwork.

Gump,
Sorry about the heavy duty 520 mistake on my part. PM me with your address and I'll send you $4.

**Gumpsta** · 06-28-2011, 12:27 AM

Barnone,
Nice one! I was joking, my fault for not checking it first myself. Maybe I'll upgrade to a 520hd later. I didn't need the kit anyway, took a couple links out and used the orig master. So dont worry, I'll be fine. Took off the sai also. The motor runs smoother, especially on deceleration . I'm not gonna mess with the carb for a while cause she's running good right now. Take care Vince.