The Yamaha YG1 80 was Yamaha's first comercially successful motorcycle. First marketed in Japan as an "Executive Motorcycle" it was a way for someone to get off their bicycle and onto a motorcycle. With deep drawn fenders and mud flaps, a fully enclosed chain, and a heel-toe shifter it was possible for someone in office clothes to arive at work looking good.
First introduced in the US in 1963 1/2 it was a success here, but mostly in the trail trim. I have not seen another street YG1 in the 2 years I have been looking on Ebay. Many of the 70's motocross stars started racing YG1 trail bikes. YG's were many peoples first bikes.
The YG1 was technologically advanced for it's day. It was the first production motorcycle to have oil injection. It was also the first motorcycle to use a VM style Mikuni carburetor with a cable operated starting carburetor. These 2 advanced made the bike easier to start and more reliable. The engine is a 75cc rotary valve 2 stroke that was considered fast at the time, especially compared to the small Hondas that were it's competition. The bike lives on today, and is still being sold in Asia. You can still buy a 90cc version, and I have ridden on Tricycles in the Philippines that use them. They sound exactly the same.
My Riding impressions are:
It is hard to believe this is a 42 year old bike. Compared to some of the old British bikes I have ridden the Yamaha YG1 is positively civilized. It is small for my size, but still comfortable. The suspension is good, it handles well, and it has good brakes. The engine feels like the bikes I rode back in the 70's. It is buzzy if you rev it, and the stamped steel frame acts like a megaphone. The bike is more torquey than rev happy, and you can tell it was meant to amble along at 30 MPH the same way they drive in the cities in Asia today. I am sure you could putt around all day on a YG1 without it puking all over itself and getting loaded up like a piston port 2 stroke would. Carburetion could be a little cleaner, but compared to the Amals, Bings, and other carbonators of the day it is pretty good. Shifting is good, but kind of vague. With the old 4 ball Sachs type shifting mechanism you do not have any dogs to feel so it is more a matter of getting the shifter all the way to the stop. It shifts backward (all down) and heel toe shifters are hard for me to adapt to.....It is also easy to see why most people tossed out the enclosed chain case--Under some loads the chain starts to hit the sides making a racket.
I really like the looks of this bike. The "Eguri" sculpted tank with chrome sides and knee pads, the fenders with the little mud flaps.....I 2 toned the frame like they were painted in Japan, and the seat cover with the white sides looks early vintage Japanese, and adds class to the bike.
I had planned on a Tiddler ride around Lake Erie on this bike, but it is just too small to haul me and some gear 800 miles. Even riding around my house you have to be carefull not to get run over by traffic. Even if it would go 55mph it would still be too slow. It probably needs to be used as a pit bike, True Grits Fun Runner, or as a part of someones Yamaha collection.