Random musing about our Buells

[Endopotential]

I've been having a great time riding and wrenching my '09 XB9.

Just some random questions that I've been mulling over. I've done my Googling, and can't find answers to these small points.

- Engine braking: I haven't ridden any Harley, and only have my Suzuki GS500 parallel twin and Triumph Daytona inline triple for comparison. The XB9 doesn't seem to have much engine braking when I lay off the throttle. Is this just a function of the relatively big flywheel and long pistons of the V-Twin design? I don't mind putting our great ZTL front brakes to use

- Rear axle: The drive belt is tensioned when the rear axle is tightened, but I can't figure out the mechanics of this. In my mind's eye, I would think the rear wheel would have to shift rearwards to tighten the belt. But the axle doesn't seem to be on any cam system, and just having a taper on the axle shaft wouldn't seem to do the job. Any good explanation?

- Air box: With the transparent top cover in place, it squeezes pretty tightly on the inner lid, even at the front cutout by the gas filler. How does the huge air filter get all its air supply? It's supposed to all come from the tiny gap at the bottom of the transparent cover?

- Right side scoop: I bought this one. https://st-paul-harley-davidson-buel...xb-models-l19c
It mounts fine, but doesn't look like a complete match for the OEM left side one. The left side has a beefier and more refined front lip. Are there any better options for the right side?

Thanks Forum!

[neilrl79]

I haven't noticed a lack of engine braking on my 09 XB12R though I've only ridden it and my 03 XB9SL.

Have you had your axel out? After you slip the belt onto the pulley and the fat part of the axel engages the wheel bearing as you torque it down and this tightens the belt.

There is plenty of air gap for the engine to get more than enough air.

This scoop is the best in my opinion and most resembles the left scoop. Though it is pricey.
https://rover.ebay.com/rover/0/0/0?m...2F263520172860

[lowkey]

If you want more engine braking than the stock fueling map is set up for you can do this multiple ways. Since you have an 08 the easiest way to accomplish this is to use ECMDroid and check this box. http://www.badweatherbikers.com/buel...431/770896.jpg

You may be able to do this with a check box in ECMSpy MONO but I don't use that software so cannot be sure. Same with TunerProRT, old version of ECMSpy had this check box option. The other way (much better fine tuning the engine braking) to accomplish the same thing is to lean out the bottom TPS value rows from 1500RPM on up using TunerProRT or MONO.

EDIT:
As for the belt tension, it is as Neil said the axle taper combined with pointing the wheel towards the left of the swing arm allows the belt to be slipped on to the rear pulley. Being a single pivot design swing arm there is a variance in belt tension with its radius of travel, to combat this the stock tensioner is mounted in such a way that it takes up the belt slack if the swing arm moves downward and puts less tension on the belt as the swing arm moves upward. Free spirits offered a spring loaded belt tensioner to keep a more linear tension on the belt, I don't think it is available any longer though.

[Endopotential]

Thanks Lowkey, great to know. So if I have an '09, ECMDroid will still work? I've been dragging my feet about whether I want to play with the AF maps when the bike is currently riding fine. It does have what I think is a Buell performance exhaust with 2 pipes at the rear, and not sure if PO changed maps at all.

About the rear axle, if it had an asymetric taper such that it pushed the wheel rearwards I could see how tightening the wheel would tighten the belt. But as the taper is symmetric I can't see why this works. I know, I'm splitting mechanical hairs...

[Cooter]

Great post lowkey, exactly right

Endo, theres a couple types of Buell exhausts that have dual outlets. Post a pic. If you aren't getting any popping through the exhaust on deceleration and it runs fine, I wouldn't mess with it.
The Buelltooth thing and ECMDroid (yes works for ALL FI Buells) is much more than a tuning tool. I will help with diagnostics and there are lots of ECM Parameters to play with without changing the fuel maps, including activating the quick shifter you should get I would get one and at least see where your AFV is. That will tell you if the ECM is trying to compensate for something.

The rear axle isn't asymmetric. Its just tapered. When the rear axle is loosened, it allows the rear wheel centerline to travel forward in the big axle hole and therefore loosens the belt.

[user_deleted]

Engine braking: The XB9 doesn't seem to have much engine braking when I lay off the throttle.

a 2-stroke has absolutely NO engine braking effect. every 4-stroke has some to a certain degree. that "degree" dependent upon many variables. both 984 and 1203 XB's have tons of "engine braking" effect.

Rear axle: The drive belt is tensioned when the rear axle is tightened

that is incorrect. the function of the unique rear axle design is to "center" the wheel assembly and properly pre-load the wheel bearings. the belt tensioner does precisely what its name implies....not the axle.

Right side scoop: doesn't look like a complete match for the OEM left side one.

never intended to be. inner scoop/outer scoop/3 attachment screws part of the original Ulysses "heat deflection comfort/service kit" and dealer installed. it was never designed to be a precise symetrical match to the factory left scoop for a few specific reasons.

[lowkey]

Thanks Lowkey, great to know. So if I have an '09, ECMDroid will still work? I've been dragging my feet about whether I want to play with the AF maps when the bike is currently riding fine. It does have what I think is a Buell performance exhaust with 2 pipes at the rear, and not sure if PO changed maps at all.

Sorry thought I read you have an 08 but yes all listed software will work with your 09 as well. As for fine adjustments within fuel timing maps you won't be doing that with ECMDroid, you CAN do it but you would need to edit the hexadecimal data which I do not recommend... the check box option I posted a picture of is about how deep you can go using ECMDroid. Think of the check box option as a blanket 96% on decel. MONO or TunerProRT will allow the fine tuning of fuel/timing maps (at the cell value) along with a bunch of other settings both check box based and value changes.

EDIT:

Wanted to see if I could find how much fuel was being removed if the check box was selected. I used ECMSpy (old version) and saved the EEPROM with the box checked. I then opened the EEPROM with TunerProRT and you can see the fuel reduction is 96% from 5500RPM to 1200RPM (this applies to BUEIB DDFI-2), you can also see how easily these adjustments can be made using TunerProRT with the simple slider for percentage of fuel reduction and adjusting the RPM window in use.
Decelration Fuel Cut.jpg

2nd EDIT:

Disregard the above statement as it applies to the "fuel cut" check box from other software. I saved 2 EEPROM's, one with and one without the box checked for fuel cut in ECMSpy. I loaded both EEPROM's in TunerProRT and get identical values in deceleration correction, I've yet to find the correlation between checking the box and seeing the change in TunerProRT BUT the same setting can be accomplished in TunerProRT by moving the slider all the way left giving a value of 0% (0% = 0 pulse width = cell value 0%). I also loaded MONO and followed along the tutorial on ECMSPY.com regarding fuel cut.
corrections_deceleration.jpg
The adjustment can be confusing as both have a value of 100 in the picture but the deceleration correction of 100% = no cell value change = no reduction in fuel and the check box 100% = 0 pulse width = cell value of 0%.

3rd EDIT:

Alright found the problem... I've been using the XDF-lite, now that I've loaded the full XDF-V5 I found the check box along with other stuff I've been looking for within TunerProRT for a while now. On a side note now I can finally close up the closed loop window!!!
Fuel Cut enabled TunerProRT.jpg

[Endopotential]

Thanks again lowkey! That's really getting into the weeds of ECU programming. Man, I may just have to take a road trip to AZ to have you tune up my bike!

[lowkey]

No problem Endopotential, I've been working on a project for a while now (hardware side) that I hope to test and share the results in a youtube video series. I'm finishing up the last of the wiring harness for the project today. The series will start with base maps and progress to the finished maps, along the way I will go over the software settings used and most importantly cover the "how and why" when making a change. With the new piece of hardware I'll be able to feed the data right into the ECM so when I go over a datalog in a video the changes will be visible. When my EEPROM is finished I was going to go back to the same base maps as before and perform the different wide spread forum procedures for tuning "blind", such as datalogging the rear narrow band sensor, running it through MegalogViewer and adding the 2% to the front map, then compare the resulting maps against the previous finished EEPROM to see how close this method actually gets. I have a few more ideas I'd like to cover but once I start uploading I'll be looking at the comments section for what people want me to cover.

I've been watching this series https://www.youtube.com/watch?v=dHe2...KeyTFEFlWWwuc6 and going to try my best to mimic the same detailed approach, obviously I won't have the dyno but I'll be using a datalog in place of it to show the effect on the changes.

Actually the first video I think I'll cover setting up the fuel table cells for idle and cover the "square idle" procedure since there is always a new thread popping up about idle issues.

[njloco]

Being as total novice with computers in general the one thing I've noticed about idle problems is , most haven't done a TPS reset after their work. Once I get set up with a Bluetooth,, I'll probably be the one asking for help. I'm sure your video's would be of great help for me in the future.

Thanks for going through the trouble.