It depends what environment your racing in.

If its in the sand, id say the quad will win. The 2 wheelers are difficult to launch good out of the hole in sand.

If its on hardpack or asphault, I think the 2 wheeler would win.

 

so how would a 700r with a kms turbo and no other mods hold up against a 250 dirtbike (probably heavily modded and a pro rider)
the 700r will have an OK rider, well towards a pro anyways