HOW
The Airforce earth bonding method is as follows:
• Clean all contact surfaces with Scotchbrite or ~240 grit sandpaper, back to bright metal. Edit : Don't remove the tin/solder or Nickel coatings from the brass or copper lugs as the coating serves a purpose in isolating metals of different reactivity
• Spray all contact surfaces with a cleaner/corrosion inhibitor that “…improves electrical properties”, like CRC 2.26. (Edit: it actually does! - I dipped a penny in it and it removed the tarnish)
• Torque up the joint while the contact surfaces are still wet with the cleaner/corrosion inhibitor.
Edit: As Cooter pointed out below, there is a time element here too. Clean, spray and torque up quickly, don't clean one day and spray and torque up the next.
• Clean off the exterior of the joint with contact cleaner (CRC Brakleen or carb cleaner works too).
• Spray the joint with a waxy corrosion protectant like CRC CPC400, to stop water seeping in and corroding it again.
'Clean all contact surfaces … back to bright metal’ (e.g. on the braided earth strap) means cleaning:
• the engine and frame surfaces where the joints bolt up (at least on the engine side)
• both sides of each end of the dog-bone link
• the new earth cable lug
• as well as both sides of each end of the braided strap itself.
A tap into the threaded holes and cleaning the underside of bolt heads and their threads and washers is not strictly necessary now, because the bolts and the frame or subframe don’t need to carry any current. Loctite on bolt threads won’t affect joint conductivity either. However if you don't want to add extra wires then the bolts and washers and thread all carry current and must be cleaned and Loctite will affect the resistance of the joint. (see the checklist in https://www.buellxb.com/forum/showth...-stop-misfires for additional things)
I’ve only found 5 earth joints in the standard wiring on a Ulysses:
• Two bolted inside the rear cast subframe,
• One at either end of the braided earth strap between the frame and cylinder head bridging the dog-bone anti-vibration mount above the engine,
• One bolted to the front of the steering head.
Edit:Also the connectors between the ET and O2 sensors' wiring and wiring harness count as earth connections and the ECM fuse in a way also - if corroded they will produce voltage drops that act the same as corroded earths to the frame.
• Other XB’s have slightly different arrangement of earth points (see https://www.buellxb.com/forum/showth...-stop-misfires & https://www.buellxb.com/forum/showth...y-and-Solution where Lunatic talks about 3 different earth wire positions at the front of the frame)
Sizes & lengths of extra cable and wire for a Ulysses are:
• Cable from braided strap to battery negative = 20 - 25mm2 cross section and 29” long (eye centre to eye centre). Check length on other XB’s (shorter frames and/or different subframes).
• Wire to steering head earth bolt = at least 0.75mm2 cross section and 36” long + however much is in the connectors.
• Wire to rear coil mounting bolt = at least 0.75mm2 cross section and 12” long + connectors.
• Wire between subframe earth points = at least 0.75mm2 cross section and 6” long (eye to eye). Check on XB’s with different subframes.
• The cable I used was a 20mm2 earth cable from a small-car wiring loom (free from a wrecker). It already had a brass lug crimped and soldered on, to bolt to the battery. I cut it to length and got an auto electrician to crimp and solder a lug on the other end.
Crimp-on lug:
• get one sized for the cable + 2 extra wires, with as big a surface area around the 5/16” hole as you can.
• get it soldered as well as crimped (belt and braces).
• Heat-shrink a sleeve that has glue inside it, over all 3 wires, to strain-relieve the 2 smaller wires so they don’t break from vibration as in the RH photo above.
Spraying CPC400:
• use cardboard behind the joint to give room to allow the spray to get to the back of the joint and rags or paper to catch the overspray.
image (15).jpg
• use a heat-gun/hair dryer between coats to flash off the solvent, to build up the film thickness.
Edit Added: Moarant posted this https://www.buellxb.com/forum/showth...ng-(-3500-RPM), which shows that doing continuity testing didn't pick up that the earth to the ECM was bad. Through some inspired guesswork he figured the ECM earthing was the problem and added an extra earth wire spliced into the ECM earth leads and running directly to the battery, which cured his problem.
There are 2 possible causes I can think of for this:
1. Since the bike is a Lightning and the ECM earths on the opposite side of the subframe to the battery, that the joint between the sub-frame halves was corroded - fix with a wire between the earth points like on my Uly, or
2.That the crimp on the earthing lug was bad. I measured the resistance of my earth wires from the black ECM plug back to the sub-frame lug and found 7 Ohms resistance, however my misfire was cured by the earth cable and the high resistance crimp didn't seem to be part of that problem. After measuring, I did spray that joint, including the crimp, with CRC2.26 and since then the resistance has been lower every time I've measured it. That could be my poor measuring technique, but might also be the effect of the CRC2.26. I got an electrician with a Fluke DMM to measure it again today and the the resistance is back to near zero (as it should be) - so I won't be changing that crimped lug - but will keep an eye on it.
Whatever be aware that crimps can go bad over time if they weren't made right to start with and be a source of voltage drop, which could cause a misfire like it did for Moarant. You'll only pick them up by measuring their resistance with a sensitive DMM, not by continuity testing.
My ‘07 Ulysses had an intermittent misfire that was 99% fixed by running the earth cable from the braided earth strap to the battery negative and cleaning/corrosion-inhibiting both ends of the braided earth strap joints and both battery terminals as above (the last 1% was fixed by richening the mixture). The extra earth wire to the ignition coil mounting bolt didn’t make any difference on my bike, but probably would have if I hadn’t put in the earth cable and cleaned all the joints. However, because it’s so important to quash stray voltages, which may even be between parts of the engine, I did it anyway. I believe you should too.
In an ideal world, Buell’s stock earth wiring works. But, as many people have found, if the bike starts to misbehave you have to clean the earth connections; the method given will clean and protect the standard wiring loom connections properly. Probably, just applying the Airforce earth bonding process to the standard wiring earth points would be enough in most cases. However, that still won’t improve the joints between the subframe and main frame and may not be enough to suppress induced voltage effects on the Engine Temp and/or O2 sensors. The earth cable from the braided strap, and the earth wire from the coil mount, are effective for this - jv
Edit: there is now a checklist of the above on this link https://www.buellxb.com/forum/showth...-stop-misfires