Most motorcycle people can point out or name a Works bike or Works part as there have been thousands of bikes and parts that fall under the umbrella term "Works" but what does the term really mean? How did the term come to be applied to racing? These are the questions that most people probably don't have a good answer for. It is kinda like the term "GIFs" people can point them out but most don't know what term means or how it even got applied.
The term "Works" as applied to motorcycle racing is most likely was derived from Skunkworks, which as some in the aviation industry will automatically recognize as having a tie to a division of Lockheed Martin. Aviation buffs will also know this division was formed sometime during or just after World War II. Skunkworks was Lockheed Martin's sort of think tank division where engineers were allowed to test and develop ideas without the restraints of production feasibility or governmental regulation until put into production for mass use.
Now that is all fine and dandy but what does the term really mean when applied to racing? Long and short of it "works" generically means, a new idea, physical part or in the case of a bike that is not currently in production or is designed outside the normal channels. "Works" parts or ideas also don't necessarily have to conform to current rules and regulations giving designers and engineers the freedom to develop or test ideas that may be unconventional.
Even though motorcycle racing (in the US) has been around well before World War II, it wasn't until after the war in the prosperous 50's would lead to a boom in motorcycling and racing. Savvy motorcycle manufacturers and tinkerers, some of which built their own bikes in the pre-war era, found the new venues, races and of course advertising to be a way to garner enthusiasm for their product. Enthusiasm driven by race wins. Previously hand built bikes using off the shelf parts and custom bits were the norm as very few (almost none) manufacturers actually built "ready to race" bikes, so in a sense every bike on the track was a "works" bike. Later as organised racing series with classes and regulations to keep the racing tighter and more fair. Enter the "works" rule. Production race bikes have to meet homologation rules but there is an allowance for one off bikes or parts to be used under a "works" rule. Typically works parts and bikes are used to refine ideas that may (or may not) eventually make it onto a production bike. Case in point my photo example of an idea for a front suspension that from reports worked very good in terms of performance, but was too high of cost to manufacture for mass production. It does look sexy doesn't it?
In recent years full "works" bikes have not been as prevalent, it is time for you to respond, what do you think the reason is?