- Yamaha XS 650
name = Yamaha XS 650
aka = XS-1, XS-2
manufacturer = Yamaha Motor Company
predecessor = none
parent_company = Yamaha Corporation
engine = 654cc, 4-stroke, parallel twin, air-cooled, SOHC, 2 valves per cylinder
transmission = 5-Speed sequential
ignition = Contact point-pre 1980CDI-post 1980
carburetion = Dual Mikuni Constant Velocity
frame = tubular steel
power = 53 bhp @ 7000 rpm
dry_weight = 450 lb
fuel_capacity = 3 U.S. Gal
similar = BSA A65, Laverda 750S,
When the Yamaha XS 650 was launched in
1968it had one of the most advanced engines in its class of large parallel twin motorcycles. The engine and gearbox are unit constructionwith the crankcasesplit 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 constructionwith separate engine and gearbox. The XS 650s valves are operated by a single overhead camshaft(SOHC) whereas almost all contemporaries in its class have pushrod valvegear. In 1968 only the Laverda 750S, also launched that year, matched the XS 650's modernity of unit construction and SOHC valve operation.
However, like its contemporaries in its class the XS 650 has a 360° crank angle. This provides an even firing interval between the two cylinders, but also generates some vibration caused by the two
pistonsrising and falling together. This vibration is particularly noticeable at idle, and may be considered desirable or undesirable depending on the rider's personal preferences. This also can be a problem when the bike is put onto its center stand while the bike is running because the bike will have a tendency to use the vibrations to walk backwards. Even this phenomenon may be desirable because it opens up the possibility of backwards center stand drag racing.
1970model was designated the XS-1. Subsequent models were XS-1B ( 1971), XS-2 ( 1972), then they changed the model designation from XS to TX. It went TX ( 1973), TX-A ( 1974), then they changed it back to XS but went on with the alphabetical suffix, using XS-B ( 1975), XS-C( 1976), XS-D( 1977), XS-E ( 1978), XS-F ( 1979). 1979 was the last year of the so-called "Standards" (owner's term meaning opposite to Special). The Es and Fs also came in Special form: XS-SE (S for Special) and XS-SF. From then on they were Specials only to XS-SG, XS-SH, XS-SJ, XS-SK. There was a Special II (Two) model designation in 1979 (XS-SF-II), 1980(XS-G), 1981(XS-H) which were models with less chrome parts and drum rear brake (1979, 1980) or wire wheels (1981) versus disc rear brake or cast wheels.
The first two model years (XS-1 and XS-1B) were kick start only, with an electric starter added from the 1972 model year on. This had a compression release added to the front left exhaust tappet cover resulting in a square versus triangular cover found on the other exhaust and intake covers. Upon removal of the compression release mechanism in 1974 due to uprated starter, the square cover at the left exhaust valve was continued.
All wheels (chrome rim wire, aluminum rim wire, seven-spoke cast aluminum) swap on all years.
*Drum fronts on early models are on their own.
*Pre '77 & post '77 fronts have different (offset) brake discs, the wheels swap but not the discs.
*Drum rear wheel into rear disc frame needs the rear drum frame
*Disk rear wheel into rear drum frame needs the rear disc frame swingarm and also needs brake master-cylinder lugs welded to the frame.
Handling differences on swapping rear wheels:-
*Standard rear tire is 110/90-18. Special rear tire is 130/90-16. Because the Standard tire is narrower it corners quicker. Because the Special tire is wider it's steadier in a straight line. Overall gearing will not change as the two tires are essentially the same outside diameter.
*Left-side front disc brake (omitted on North American models only) can be added by bolting another disc to the left side of the wheel (the bolt holes are there) and the left-side caliper from an SR500, XS750, XS850 or XS11 (the fork lugs are there) and adding the other brake line & a double-length banjo bolt. XS650 stock
master cylinderstill works. The system needs very careful bleeding, stainless steel wire braid hoses improve the feel.
Standard (large) and Special (small)gas tanks interchange but must keep their own gas caps because they are different.
Mid-'77 the front forks had a major redesign, fork tube diameter increased from 34 to 35 mm and internals were changed (although this also holds true for various years of the same tube size). The entire fork assembly (with triple tree) will swap either way but fork parts are not equivalent. Also the brake caliper changed from a 48mm dual piston cast iron design for the 34mm fork to a 40mm aluminum single piston floating caliper for the 35mm forks. The brake caliper mounting lugs on the fork sliders are of different spacing for the 34mm and 35mm forks so the calipers can't be swapped.
End of Production
The XS 650 was produced until
1985. In the United States, the last model year was 1983with Canada, Europeand other markets continuing into 1984and 1985. However, many US models were left over due to overproductionand an economic recessionand brand new 1982and 1983 models could still be purchased in 1987at some dealerships.
* [http://xs650temp.proboards29.com/index.cgi/ XS650 Garage forums] ]
* [http://beaver.vinu.edu/650.htm Yamaha 650 Society] ]
* [http://www.xs650.nl/ Yamaha 650 Twin Klub The Netherlands] ]
* [http://www.yamahaclub.com/ Yamaha Owners' Club] ]
* [http://www.xs650.org.au/ XS 650 Club of Australia] ]
* [http://650wiki.org 650wiki.org] A wiki site dedicated to the technical aspects of the XS 650
* [http://www.650central.com/ 650 Central] : Purchase parts, accessories and books for the XS 650
* [http://www.mikesxs.com/ Mike's XS] : Purchase everything XS 650
* [http://www.bikeszone.com/content/view/626/46/ XS-V1 Sakura (2007)] : As a tribute to the first XS 650, the XS 1, Yamaha created this prototype shown at the 40th Tokyo Motor Show 2007
* [http://www.thechopperunderground.com/forum The Chopper Underground] XS650 Customs and technical info
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