The YA-1 was the first motorcycle manufactured by Yamaha, from 1955 to 1958, though its design was heavily influenced by the pre-war German DKW RT125, and its numerous post-war derivatives. It had a tubular bicycle-style frame carrying a 125cc two-stroke engine like the RT125, but differed in having springing on both front and rear forks.
The model is the latest, and apparently the last, model published by Yamaha Paper Craft. It was brought out in December 2017 amid much fanfare, to celebrate the 20th anniversary of their paper model web site. Given this enthusiastic promotion it was a major surprise to see them announce only six months later that the site would be closed at the end of September 2018. The model is billed as being in their "Ultra-Realistic" series, though it is to an even larger scale than the others in the series. No scale is explicitly given, but the overall length of the model is cited as 49.5cm and Wikipedia lists the prototype and being 1980mm long, so we get a scale of 1:4.
This is far too big for me, so my version will be at my usual 1:14. This is a significant reduction, so I can expect to have to rework some of the components, possibly with some simplification to make things buildable. I hope the result will be reasonably faithful to the original model, though. We have already seen excellent builds by
spiral and (sadly unfinished)
huubvc, so I shall not go into too much detail, but will show a few photographs and touch on some of the modifications I have had to make.
Alan