I followed John Vreede's excellent outline for electrically bonding the engine, main and sub-frames to each other with copper conductors. Below are a few pictures showing what I did.
I used ring connectors crimped and soldered to 16 AWG and 4 AWG conductors. I also soldered the ends of the Ground Strap, ran a 5/16" tap down the tie bar holes and a 1/4" tap down the sub frame holes.
I connected the coil's rear mounting bolt to the tie bar mounting bolt. From there I ran a 4 AWG cable to the left side of the sub frame. Also bolted to the subframe's left side is the negative battery wire, another battery minus wire and a 16 AWG bonding wire connected to the right side of the sub frame where the two minus ECM wires are connected.
Results: I own two 2007, XB12STT Buell's. After bonding engines on both machines run smoother and seem to have a little more zip.
Never thought to run the cable to the engine side of the tiebar.
Lower resistance but probably more vulnerable to cracking off at the lug due to engine vibration on that side
Off topic:
Where did you run the PCV breather hose to? (I used a tee as well, but took the hose off the rear side of the tee. There was not much space to run it other than down across the top of the shock and behind the right hand passenger peg casting where it dribbles a bit, kinda unsightly) - jv
>>>Never thought to run the cable to the engine side of the tiebar. Lower resistance but probably more vulnerable to cracking off at the lug
Maybe but not very likely, its pretty heavy duty, (heavier than the lugs on the tie bar ground strap). If it should ever fatigue its not a critical component and the bike would just start running the way it did Before I did all the Earth wiring.
>>>Where did you run the PCV breather hose to?<<<
I have an oil catch can similar to the one pictured below bolted to the oil cooler. I connected a hose from each PCV valve to a Tee. From the tee I ran a hose down to the catch can. There's an outlet port on the back of the can. I used a hose to connect it to a course metal bodied metal screen filter which I tucked up out of sight between the frame and the top of the muffler.
Another shout out and big thanks to John Vreede. I bonded and Earthed both of my 07 TT's. With all the wildfire smoke it wasn't until today that I could take the 2nd bike out for a decent, (76-mile) run.
Happy to report both bikes are running fantastic. Both are smoother and peppier, and the old Butt Dyno tells me their performance is equal. In the past one had a little more zip and I could never figure out why.