The Yamaha XS650 is a mid-size motorcycle made by Yamaha Motor Company. The standard model was introduced in 1968 and produced through 1979. The "Special" cruiser model was introduced in 1978 and produced through 1985. The XS650 began with the 1955 Hosk SOHC 500 twin. After about 10 years of producing 500 twin, Hosk engineers designed a 650 cc twin. Later the Hosk company was acquired by Showa Corporation, and in 1960 Yamaha had bought Showa with Hosk's early design of 650 cc twin.
When the Yamaha XS 650 was launched in 1968 it had one of the most advanced engines in its class of large parallel twin motorcycles. The engine and gearbox are unit construction with the crankcase split horizontally for ease of assembly whereas almost all contemporaries in its class in 1968 are either unit construction with a vertically split crankcase or pre-unit construction with separate engine and gearbox. The XS650's engine was used in AMA Professional Dirt Track Racing by national champion Kenny Roberts. In 1968 only the Laverda 750S, also launched that year, matched the XS 650's modernity of unit construction and SOHC valve operation.
We've already started work on this baby. We started with the frame we built last winter and have a solid engine and tranny to start with, it came off a nicely running bike with low miles and should just need a freshen up . She will rock 19'' wheels front and back, a girder front end, and be lean and low. Going for some sort of cross between boardtrack racer and bobber, with a touch of salt flat.
*** Update Sept 11th, 2015***
In the last photo you can see a quick and dirty wiring diagram. This will be running an upgraded electronic ignition system from Pamco with the E-Advancer, new ignition coil and plug wires. It will still use a battery but no starter motor will be installed.
Next up is finish the tank mounts, fab a seat pan, seat mount/pivot, and seat springs. Once we settle on a seat design we will weld the rearset mounts onto the frame, start on the front end, and then the exhaust.
** Update Sept 30th, 2015**
The tank we are going to use is from a Yamaha GT80. In the first photo you can see the completed brake caliper stay. Holes have been cut in the neck gusset to lighten up the front and for looks. We have also got the seat pan cut and mounted, but we still need to set up the suspension for it. It will use a single shock with adjustable preload and the angle of the shock will match the angle of the shock on the girder front end. We also completed the wiring harness and installed the reg/reg, Pamco ignition with electronic advance, and new ignition coils. In the last photo you can see the tank, it will use rubber mounts under the tank and a leather strap that runs parallel to the frame and matches the seat to hold it in place.
Next we will start work on the front end, finish the seat and shock, and fab up a battery box.
**Update Oct 29th, 2015**
Got out the engraver and etched in the logo into the tank cap. What was just messing around to begin with turned out pretty good! Battery and electronics box is done, it also houses the ignition switch. The rear fender is shaped and cut. The girder is on! Still need to make some minor adjustments (longer shock, weld on brake caliper and headlight mounts, etc.), but its looking good!
**Update Nov 12th, 2015**
Exhaust and seat mount/shock done!
***Update Dec 16th, 2015***
After finishing the girder top links and checking the everything is operating as it should, we can take her apart again, clean, and paint!
***Update Mar 27th, 2016***
Frame is powdercoated satin black, tank and fender painted with a brushed aluminum finish, seat is upholstered with black leather, and reassembly started. Need to craft the tank and battery box straps using the same leather as used on the seat. Waiting on the motogadget speedo but all other electrics are done
Back from first of many test rides! Went off without a hitch, just need to adjust the jetting a touch and install the tank emblems.