is it a 1983 suzuki gr650 Tempter? or more likely this 2002 Suzuki ST400 Tempter Retro http://www.flickr.com/photos/kenjonbro/3428849599/
Yep, probably a 400cc Suzuki if it's from Japan, the 650 version sold in the US as the "Savage" has a taller cylinder. Even the 650 is kind of weak, but has a long stroke and sounds like an old BSA with the right exhaust.
