Honda CRF250L - Tuning AFR+
Click pictures to supersize.
O2 Sensor and Bung
Moment of Truth
Why did I switch from the EJK to the AFR+ ???
I installed the Dobeck AFR+ kit on my CRF250L.
• My CRF250L has been modified as described on my modifications page and on my CCC modifications page.
• I have removed the PAIR control valve: see my CCC modifications page.
• The Honda ECM has been changed to the 2014 version, Honda part number 38770-KZZ-914.
• I have installed the B&B 283 big-bore kit.
• I use non-ethanol gas only, and in this area, it is premium grade (91?).
The AFR+ instructions show: "The AFR+ is legal ONLY for closed course vehicles. The AFR+ is not applicable, nor intended for use on Emissions Controlled street, highway or off-road vehicles. The AFR+ is not applicable, nor intended for use on aircraft".
My intended use of the AFR+ is as follows:
On a closed course track near my house and on nearby private property, I will use the AFR+ closed-loop mode.
In any other area, I will disable the AFR+ closed-loop mode and use only the Honda ECM. The AFR+ instructions tell how to disable/enable closed-loop operation.
Where to buy: CRFsOnly - about $425. Early adopter price $325.
My installation is shown below; it is merely a guide showing the way I decided to do the install. Use your own judgement about how to install your kit. Follow the instructions.
O2 Sensor and Bung
The very first thing I did was to have the O2 sensor bung installed in the exhaust pipe. A local business owner in Salida welds as part of his business and he has done some very good welding for me in the past, including welding a bung on my WR250R exhaust pipe. He and I discussed where the bung should be mounted. The requirements are that it be mounted vertically or slightly inclined towards the engine, that it not interfere with the heat shield, and that it not be too far away from the exhaust port.
This looked like a good place to mount the bung. Once we got the exhaust pipe in our hands, we found a problem.
The first 18" of the exhaust pipe is double-walled. The nested pipes are welded together at the exhaust flange and the joint where a single-walled pipe is welded. This second pipe has a slip joint on the tail end that connects with the s-bend of the muffler pipe. There is also a spot weld on the inside radius of the first bend in the nested exhaust pipes - probably to maintain the position of the nested pipes during mandrel bending.
Are the nested pipes fitted with no clearance between them or is there an air gap?
If there is a gap, is it filled with air or another gas or possibly sodium?
If we drill through both pipes, will an external weld on the bung leave any gaps where exhaust gases can get between the nested pipes?
Rather than deal with these unknowns, my welder suggested moving the bung another 3 to 4" further away and onto the single-walled section. I agreed.
Here is where the bung was finally mounted. The edge of the bung is about 1" from the weld seam. Front is to the left.
The bung supplied in the kit is 1" long. The bottom of the bung must be cut away with a fish-mouth cut so it conforms to the exhaust pipe. A hole is drilled into the exhaust pipe (diameter = i.d. of the bung). The bung is then positioned on the outside of the exhaust pipe and tack-welded. After a check for clearance, the bung is final welded. An alternate method of mounting the bung inside a hole cut into the exhaust pipe is not recommended. The picture shows a typical cut and joint. You don't want to cut too much material away; the tip of the sensor is all that needs to protrude into the exhaust pipe.
Here's a view inside the exhaust pipe showing the tip of the O2 sensor. It looks like it protrudes into the exhaust pipe just about the depth of the tip. You can also see the weld lines.
I'm working on getting a clearer picture...
It looks about 3/32" away from the heat shield.
The bung tilts ever so slightly towards the engine to just clear the heat shield. You could tilt it a bit more and get more clearance - perhaps up to 3/8" before the upper part of the sensor gets too close to the engine. Be careful...
After the bung was mounted on the exhaust pipe, I re-installed the exhaust pipe, using a new exhaust pipe gasket (Honda part number 18291-MEB-670). If you don't use a new gasket, an exhaust leak could allow fresh air into the exhaust pipe possibly causing an incorrect AFR reading. Don't mount the O2 sensor until after the exhaust pipe is on the bike; you don't want to ding the sensor while you're trying to get the exhaust pipe in place.
A note of caution. The O2 sensor is shipped with a plastic cover on the end, protecting the sensor tip. Try to leave this cover on at all times until just before you screw the sensor into the bung. Avoid touching the tip of the sensor. Note also that the sensor threads are covered with black grease. Avoid getting this grease on your fingers - it spreads at the slightest encouragement and is very hard to clean off completely.
Once the pipe was on the bike, I threaded the O2 sensor into the bung, holding the sensor wires straight up and rotating them as I screwed the sensor into the bung. I tightened the O2 sensor using a 22mm open-end wrench. I left the sensor wire unplugged for now.
Another item I wanted to finish before doing the wiring was the AFR gauge installation. The location of the gauge will determine where the connecting wire is routed.
Dobeck sells optional parts for mounting the gauge on the handlebars, but I have already used all my handlebar space up. I chose a spot just to the right of the stock instrument panel. I wanted to mount the gauge so it was protected from the weather and after casting about for a suitable enclosure, I decided to use Kydex to make a small shield which would provide coverage and a firm mount.
The gauge is not really angled as shown; my super wide-angle camera does that on close-ups. I'll get a better picture soon.
The Kydex shields the gauge from direct impact of rain/snow while riding. I'll carry a small plastic bag for use when the weather gets extreme. I don't think I'll be checking the gauge all the time while riding, so covering it will not be a problem.
This picture was taken after all the wiring was finished. The engine is idling here - kinda lean, huh?
I removed the seat and raised the fuel tank so I could easily install the wiring harness. See Removing the fuel tank for hints on raising the fuel tank.
The first task was to lay the harness in place, taking into consideration where I mounted the AFR gauge and where I wanted to place the wideband controller. There is no need to have access to the wideband controller because it has no buttons or lights - they are on the AFR gauge. I decided to mount the wideband controller under the seat and that dictated how the remaining harness would be placed.
I placed the controller on the rear fender, then fed three wire bundles through the frame. The connector ends passed easily through the frame at this point.
I moved the controller into the open area where the two velcro patches were; final positioning came later. I moved the three wire bundles so they passed behind the snorkel. I routed the single black ground wire to the left side of the frame.
I routed the largest wire bundle (with the O2 sensor connector on it) along the frame, tucking it under the frame.
Going back to the O2 sensor wire, I passed it behind the frame and back to the rear brake reservoir, pulling it out slightly. Take a look at the picture two down from here to see where I routed the wire (under the frame crossmember).
I connected the wire bundle to the O2 sensor wire.
I pushed the joined connectors downward and under the frame crossmember. I zip-tied the wire bundle to the frame crossmember.
Note where the sensor wire is positioned.
I undid the zip-tie near the sensor wire and secured it around the sensor wire and the hose.
I passed the gray AFR gauge wire bundle along the frame, over the resonator, through the frame joint, and on towards the steering tube. The blue painters tape is temporary.
I passed the black wire bundle along the frame and into the area by the throttle body.
I removed the connector on the front of the throttle body. I plugged this connector into one of the connectors in the black wire bundle (paying attention to male/female). From the black wire bundle, I plugged the remaining connector into the throttle body. I wrapped tape around the collection of short wires to keep the area neat and uncluttered. Note that the wires are left free hanging.
I fed the single black ground wire along the frame and other wire bundles to eventually reach the battery. I undid the ground screw and added the black ground wire to the wires already present, then screwed the ground screw back in. You may elect to get a longer screw if you have several ground wires coming in here.
I pulled the excess ground wire back to the controller at the rear of the bike; coiled the wire and taped it to keep it in place. Use zip-ties if you prefer.
I used the sticky velcro pieces to mount the controller as you see in this picture. Imagine my surprise when I was putting the seat on and discovered that the seat has a foam pad on the bottom in exactly the spot to mash down on the controller.
Not to panic. I moved the controller forward out of the way. But to do this, I had to make room for the wires coming out of the controller. I removed part of the small plastic tab - compare this picture to the one above to see where I removed the piece. I used an exacto knife with a heated blade. Be careful you don't dig through the plastic on the bottom.
At this time, I adjusted the wire bundles so the slack was where I wanted it. Slack space can be either back near the controller or forward under the fuel tank. I split the difference, making largish looping curves at the back over the airbox and fed some extra length forward under the fuel tank. I added small zip-ties in several places to secure the wire bundles to the frame.
After I mounted the seat in place, I checked to see that it was not touching the controller.
Lastly, I routed the gray AFR gauge wire bundle forward along the frame, above the throttle and clutch cables, then along the steering tube and into the area behind the headlight. Depending on where you mount your AFR gauge, you will route the gray wire to the short AFR gauge wire and connect the two. Pay attention to the tag on the wire and secure the wire to prevent flexing.
I re-installed the fuel tank, being careful not to pinch or bind any of the new wires, or the ones already on the bike.
Here's a look at the sensor area, ready to ride.
Moment of Truth
The instructions warn - "Refer to General Operating Instructions. DO NOT SIMPLY TURN THE KEY ON FOR TROUBLESHOOTING". So I read the "Startup" section in the General Operating Instructions. When I turned on the key, the LEDs scrolled back and forth and the needle swept across the gauge. I started the engine. The needle popped around to 15, very lean. After a suitable warm-up, I made note of the AFR settings for each mode (on a 3x5 card for reference). I did not make any changes before the first ride, as the instructions noted. My test ride was 5 miles long. I paid attention to the AFR gauge and made notes of the readings at various throttle settings. Everything worked just as it was supposed to, and I'm now looking forward to fine tuning the system to suit my riding style.
Looking back at the install, I can say that this was very easy to do. There were no critical decisions to make (except for the bung location, but that kinda worked itself out). Everything fell into place and it worked when I turned on the key. How easy was that?
I went for a 65 mile dirt-road ride in the lower elevations nearby (8,000-10,000'), pushing the CRFL a bit to see how well the acceleration function worked and checking full throttle response. All seemed well; the CRFL is running better than it did with the EJK. Later, after a chat with a Dobeck tech support person, I discovered that the acceleration function was still set to open loop mode and that I could change that if I wanted. Done and done and I'll see how it works on the next ride.
I'm VERY happy with performance thus far...
I plan to follow-up with more ride reports, tuning results, and fuel mileage. Stay tuned...
The AFR+ kit comes with 8 pages of documentation:
AFR gauge mounting instructions
Generic installation instructions
General operating instructions
Fueling modes explained
Oxygen sensor bung installation instructions
List of miscellaneous topics including support and warranty information
In addition, the Dobeck web site has more information here AFR+ Technical Support :
Understand Adjusting the Modes and Setting the Auto-Tune AFR Values
Understand Diagnostic Mode
View Installation Info
Receive Tuning Tips
... and MORE!
Why did I switch from the EJK to the AFR+ ???
I had the EJK kit on my CRF250L from October, 2012 to May, 2014. It improved the performance of the stock CRFL and accomodated the addition of performance mods (exhaust etc). But the EJK is an open loop controller, and as good as it is, I have found closed loop AFR controllers to be superior. Test rides in the months to come will tell me if that is the case with the AFR+, but I have no doubts about the results.
The table shows miles ridden and fuel used to give MPG. Time and MPH are shown sometimes. Gearing, FI settings, and mods which directly affect engine performance and thus MPG are also shown.
This table is for the modified 283cc engine, plus mods and CCC mods as noted, including the AFR+ kit.
I use non-ethanol gas only, and in this area, it is premium grade (91?).
Note: Not all miles ridden are logged for mileage checking.
|5/17/14||64.6||.96||67||n/a||n/a||13/43||AFR+ original settings||NoCat|
|9/1/14||51.1||.79||64||1:48||28.4||13/43||AFR+ original settings||NoCat|
|9/19/14||100.2||1.59||63||3:30||28.6||13/43||AFR+ original settings||NoCat|
|10/17/14||90.4||1.27||71||4:04||22.2||13/43||AFR+ original settings||NoCat|
NoCat = stock muffler, catalytic converter removed
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