Almost all bikes I have had have some kind of clunk to verying degrees when shifting into First from neutral. I have always assumed it is normal as it doesn't seem to do any harm and only happens from a standstill when first engaging bottom gear. I honestly don't think it is anything to worry about.
You should try BMW. They actually move

when engaging first gear. and the clunk is noticable when changing to other gears as well. The 1400GTR gearbox is by far the smoothest I have ever ridden with.