How I tuned my XB12 the old fashioned way.

[mosquito]

I love my ’07 XB12scg! It’s light and compact and has plenty of torque and power and it’s different--a real motorcycle. It has a comfortable riding position, fully adjustable suspension, slick transmission, handles ok, stops well, gets fantastic gas mileage and it’s easy on tires. It does vibrate--a lot!
It had 388 kms. on it when I bought it from a “collector” last year and it came fitted with a Jardine pipe (loud!) and a race ECM. It ran like crap but I figured I could tune it up with a little help from guys on the board. I got the bluetooth dongle, a Windows laptop, signed up with ECM Spy and Megalog viewer. I read everything I could find about tuning and asked a bunch of questions and learned how to tweek the fuel and timing maps but I’m an old fart and not computer savvy so a lot of it was Greek to me. I got a race map and got it to start and idle ok but it still bucked and hesitated up to about 3500 rpm and backfired on the overrun from 4000 to idle. It did make lots of steady power on the gas above 4 grand but you can’t ride like that in town or all day. There’s lots of good info on the ECM Spy site and lots of help from guys on this site but I couldn’t even figure out how to log data or why I should so I got pretty frustrated and annoyed with the whole thing. I could not for the life of me figure why the ECM had to keep changing the mixture to stoichiometric except to keep the EPA happy and piss me off so I decided to tune it my way.
I got an Innovate wide band O2 sensor and gauge and installed them and a hardwire connection from the computer to the ECM. The first thing I did was make the maps for the front and rear cylinders the same then started taking fuel out below 15 TPS right from 7000 rpm down to idle until it quit backfiring. It showed about 17:1 on the gauge in that area. Then I started adding fuel up to 20 TPS from 800 to about 1900 rpm until it
idled smooth and steady but didn’t hang up when I closed the throttle.
It still bucked and hesitated up to about 3500 rpm so I looked at the timing map and found it was zero or close to it in that area, which is way too retarded. (Like me!) I advanced the whole area a few degrees at a time until it quit hesitating.
Now it runs like a good Buell should! It starts immediately cold or hot, idles, pulls smoothly from idle even on light throttle, does not pop and fart on overrun and pulls hard on open throttle! And I’m not going back to that #%&*$ narrow band O2 sensor. I still have the air/fuel gauge to keep an eye on things--it looks good mounted on the top triple tree in front of the tank, like it came that way from the factory! I’ve put about 4000 kms. on it since tuning it up and it hasn’t blown up yet! (But it still vibrates!)
Thanks to all you good samaritans who tried to help me!

[LouWambsganss]

The reason the ECM aims for stoich is due to the construction and chemistry limitations of the narrowband O2 sensor. The range where it can give any useful readings to the ECM is only a few points on either side of 14.7:1.

AF Basics 3.gif

[user_deleted]

The unwitting and unknowledged attempting to circumvent narrow-band O2 instrumentation is akin to children frolicing around the neighborhood in halloween costumes Christmas eve sporting Woodstock daisies and flowers in their hair.
warm regards,
ich

[Cooter]

The "Race ECM" written on the box doesn't mean anything. They are identical to stock ECM's. If the bike was running poorly but tested to be mechanically sound first it is possible the tune was not right for your bike. No guarantees on the other tune you tried either (source?), but it sounds more like an ECM Parameter problem than an actual tuning issue, such as an AFV that wasn't set back to 100 after downloading the correct tune. TPS re-set?

The ECM is searching for stoic (14.7-1 AFR) in closed loop (part throttle cruise) because it is the most efficient ratio of fuel and air, not "for the EPA". You don't get more or less power in CL. Thats why you've never seen a dyno run at part throttle. CL operation (where the bike is most of the time) should be efficient for ride ability. Any richer there and the fuel won't get burned completely. It will foul plugs, stink, kill MPG's, and yes, have huge increases in emissions from that wasted gas you paid for.

Did you turn off CL operation? Or are you using the WB O2 sensor as a NB emulator? If so, how much is the ECM correcting for your changes (current AFV)?

IMO, even though it seems to ride ok theres much more work to be done to ensure it is running well and safely at all times.

[Mesozoic]

I'm getting ready to datalog my '08 XB12 with an NGK Powerdex meter. I've got the analog output of the meter going to the front O2 ECM input and have the wideband sensor in the front header. Rear O2 is the narrowband... we'll see what it does. My bike runs pretty damn good, I'm just trying to eek out a bit more performance under WOT. My thinking is that by getting a good picture of what the AFR is at WOT, I'll be able to fine tune it slightly for each cylinder.