We can talk a lot about the little Yamaha YL1, as it is such a lovely motorbike.
The little 100 cc twin from 1969 with framenr. Y33-108392 is one of the nicest bikes ever to ride. The small bore (38 mm) with the 43 mm stroke make the engine smooth as an electric motor. It revs beautifully through its 4 gears and really goes better than any modern small bike!
The little AT90 (here the prototype of December 1965) was the forerunner of the YL1.
In the years that it was produced many remarkable items were offered, as you can read on the "Brochures" pages. There was a real "race-kitted" version. Yamaha supplied the "GYT" kits for the YL1 with nice chromed upswept exhaustpipes. Yamaha made these kits for many bikes, you will get a list later. A friend of mine in the UK had one of these (unused kits). One of the British dealers who offered complete "race" YL1 bikes were "Finch Brothers" of Manchester.
Sorry guys, I do not have the Partnumber and the Computer will surely say: "NA" or not available anymore......!
I agree, the rider is a little too large for the small YL1! But look, this converted YL1 has the standard kit with the chrome upswept pipes. He took the emblems from the tank, otherwise the clipons will foul it of course. Great picture.
The Japanese YL1 racers look a little more professional, fuel tanks like a small TD1. I am not sure, but also the front brake looks one size up from the standard YL1, AS1 maybe same as the rear shockabsorbers.
The English magazine "MotorCycleNews" showed this picture in their Wednesday, September 13th, 1967 issue. (It is similar to the bikes on the previous page!)The caption reads:
"This baby is a race winner"
"Yamaha latest baby, already well established in Japan, has proved itself a race winner. This racing version of the 100 cc YL-1 averaged 80,48 mph (128,84 km/h) to win a clubman's event at the famous FISCO circuit where it set a 100 cc class lap record of 83,68 mph (133,97 km/h) The bike which set up these record speeds, against keen opposition from Bridgestone, Honda, Kawasaki and Suzuki, was fitted with special cylinder heads, cylinders, pistons and carburettors. In its tuned form the Yamaha develops 18 bhp and has a topspeed of around 93 mph (148,89 km/h)"
(You can click for a larger print, sorry it is a scan from a newspaper magazine)
John LeBlanc found this pretty YL1 in his neighbour's shed! Purchased in 1966 and little used it sports the US style half chainguard and just needs a new seatcover and some cosmetic attention. (and some new tyres I am sure).
Here follow some detailed pictures from this YL1, everything is standard on this machine. First picture shows the neat handlebar layout with the controls.
The battery compartment with on the left the airfilter and on the right the rectifier assembly (this is the normal European 6 V machine).
The chaincase drive side should look like this, although in some markets the YL1 was also sold with a half-chaincase
The engine details show the attachment of the rubber induction manifold between the airfilter and the carburetors and other details.
The rear carrier was an optional extra but very popular, this is the genuine part.
The early YL1 machines had these very small rearlights and the very small flashers, which are now very, very difficult to find.
The engine from the r.h. shows the rubber tube from the "Autolube" tank to the oilpump.
My YL1 has a chrome front fender and chromed downtube to the engine. These parts were sometimes also silver painted.
Here is the wiring diagram of the 6 Volt YL-1:
And the diagram in colour
(click wiring diagram 1# and 2# as they are large size!)