Here's where the '99 is now:
1. It's running BT012SS tires; 180/55 rear and stock size front, 35 psi front and rear for general use.
2. Wheelbase is about one inch shorter than stock. To do this I had to mill the swing arm axle slots slightly and shorten the chain. This made the bike turn easier but also made it harsher and less stable.
3. The fork's low and high speed compression damping has always been too stiff for my taste. This made the fork chatter while braking and cornering hard in lower speed corners and made it generally miserable to ride over rough pavement. I increased the compression flow area of the base valves by about 50% and changed the low speed shim stacks to lessen the low speed compression damping by maybe 60%. The rebound side was left completely alone. The forks were refilled with a 5W fork oil to increase responsiveness. Wow, what a difference overall. The front end feels planted like it never really did, it's twice as smooth as before, and it lands wheelies real smooth.
4. After experimenting with the stock Kayaba shock's shim stack to decrease the compression damping (also excessive like the stock fork), I gave up and tried a new stock '03 GSXR1000 shock (at the nice price courtesy of Valvoline Emgo Suzuki
). These later model 1000s have had suspension revisions to increase compliance and it shows. I don't know if this shock is a Kayaba or a Showa, but it's quite a bit lighter than the Busa shock and has a bigger body too (more oil = better). I did increase the spring preload by about a turn and a half from stock since the bike squatted a little under acceleration. Now it seems to suit my bike's lighter-than-stock weight and shorter wheelbase just fine. Quite a bit less harsh than before but it doesn't feel undersprung or underdamped (it might on a stock Busa with stock wheelbase; the stock shock didn't feel so bad until the wheelbase was shortened). Actually, the front and rear spring rates seem well matched now, unlike before. The rebound damping might be a tiny bit limp, but there's quite a bit more adjustment available and I'm still experimenting.
Very happy camper here so far. This thing is a lot more confidence-inspiring and comfortable than it was. None of these comments necessarily apply to all Busas, just my own. I was reading moto mags last night and happened on an article that summed up the original suspension problems perfectly. It was about a '99 Bandit 1200 and they said that "the Bandit's boingers are harsh front and rear by comparison (with the ZRX1100 also being tested), with too much compression damping...the same harshness that gives it a rough ride on the highway makes it skittish in bumpy corners, reducing the rider's confidence in charging into unfamiliar corners." And then I found an original '99 Busa test where they commented about the Busa's hard ride (caused mainly I know now by too much compression damping front and rear).
