Several years ago (around 2003) there was a web site owned by Toni Mauricio, who had designed a selection of fairly simple models, mostly vehicles and buildings but with one or two oddities including a vacuum cleaner. One of the vehicles was this GasGas trials bike. The site no longer exists, though the address has been taken over by a different site showing photos of paper models with links to their originators.
The model is very simple, containing only about 30 parts - the engine details are simply printed on the sides of a tapered box - but surprisingly effective. The major failings are the wheels, which are just slab discs with spokes, brakes and (rear) chainwheel painted on the sides in bits taken from photographs. This has been done piecemeal and rather inexpertly, so the result is rather strange. I made spoked wheels and separate brakes, and also redrew the chain and sprocket.
The model is scaled at 1:6, so my version is reduced to 43% to give 1:14.