Overcoming Part Shortages: YAMAHA YB-1 FOUR Custom

Webike's Opinion

Here is a "YAMAHA YB-1 FOUR" custom by Webike community user "Lucky". Nearly 20 years ago, when the owner was still a student, he wanted a small-displacement bike that had a classic, full-sized motorcycle look. That’s what led him to purchase this YB-1 FOUR. After sitting dormant for nearly a decade, the bike is now undergoing both restoration and customization.

One of the things the owner loves most about this bike is its styling. He says it looks great even without modifications, yet he’s made quite a few custom changes. Another standout feature is the high-quality chrome finish, which is surprisingly on par with the SR400 despite its smaller size. And of course, the impressive fuel efficiency of 50 km/L is another major plus. The biggest downside is that aftermarket parts are nearly impossible to find, so it's necessary to use parts from other models. But the owner sees that challenge as part of the fun.

For the fuel tank, he replaced it with one from an RZ50 and had it buff-polished to a shine. The seat is a cafe-style single seat originally made for a MONKEY. The handlebars are HURRICANE Clip-Ons designed for the RZ50, while the vintage-style fork boots are from KIJIMA’s CD50 lineup. When the Auto Boy cylinder and piston wore out, he replaced them with a KITACO piston and a used cylinder from a Mate 90. A professional handled the cylinder boring, but all other work was done by the owner himself. Despite countless setbacks, he finally got the engine running again, making every ride now feel even more rewarding.

He also extended the swingarm himself. With larger-diameter tires installed, the stock setup left barely any clearance between the rear wheel and the swingarm, making it unsafe. On top of that, chain adjustment was nearly impossible. To fix these issues, he fabricated a longer swingarm. The last photo in the gallery shows a comparison—the top image is the stock swingarm, while the bottom one is the new version, extended by 68mm. The difference may not be drastic, but it noticeably improves the overall balance of the bike.

Gallery

Specifications