A longer wheelbase messes the bike up too. I mean, if you've got 400 horsepower, you've got no choice- you pretty much gotta lengthen the bike or it'll use you for a tent peg. But on normal bikes, you don't need to go 6-8" over, even if you're drag racing. When you lengthen the arm like that, it goes without saying that it makes the bike handle like a city bus. But beyond that, it shifts more of the static weight bias to the front tire, taking weight off the rear tire. If it didn't spin before, it's gonna now. Unless you have a good, hot, sticky drag tire on it.
I'll use my bike as an example. My Hayabusa was raised an inch or so in back, the wheelbase was shortened by 5/8", and I used tallerthan stock gearing. I did not have a clutch mod (welded clutch hub) in mine, so I had to ease it off the line carefully at 2500 rpm. I took it to the drag strip and did nothing to prep it for drag racing. I didn't lower it, adjust the tire pressures, adjust the suspension, nothing. Not even a burn-off. I just rolled to the line with the tire stone cold and went for it. It was my first time at the drag strip on any kind of motorcycle, and I was still able to rip off 1.6 60' times, tripping the 60' clocks with the rear wheel. If I can do it, anybody can do it. And because the rear tire was under the bike instead of behind it, it didn't spin once. Not even a little bit.
