3 possibilities off the top of my head:
1. rear wheel alignment is off
2. you're too aggressive with your body motion when you launch, upsetting the chassis.
3. a poorly setup rear shock in addition to 1 and/or 2
i have a k8, 1000 which i drag race, my problem is that when i launch, the bike doesn't leave straight, it most times goes to a side.
What can i do to prevent this?
mods are pc3, two brothers full system, msd launch master( set @ 7k), lowered, stretched 7inches.
If it goes consistently to one side, it could either be a technical issue or a rider issue.
If it goes to either side, that rules-out a technical issue*
Just a guess but I'd bet it's a ham-fist issue. I don't drag but on the track, being loose and supple on the grips is the difference between fun laps and terrifying laps. With your feet where they are at launch time, if your ass isn't on the seat, your hands are what is trying to haul your body mass along with the furiously-accelerating bike off the line.
In addition to everything above, think about where you are lining up on the track. I can get this if I'm just near the edge of the groove. Try a different placement of the bike and see if that helps; another lane, the opposite tire groove from the cars, etc.
Taking into consideration all things mentioned above I went through a spell of the bike moving to the right shortly after the launch. I was boggled for a while and looked into most of the issues listed....
I started focusing my my field of vision on the finish line, in other words looking where I was going instead of watching the tree and the issue subsided.. Good luck...