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Yamaha XS 650

1975
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Yamaha XS 650 — 1975
Image: Motorcycle Specs — null

Vitals

Wet weight
191 kg
Fuel capacity
15 L
Real world range
250 km
Front tyre
3.50H-19 4PR
Rear tyre
4.00H-18 4PR
Tyre pressures
1.6 / 2.0 kg/cm2 solo
Ground clearance
150 mm
TerrainTarmac

Field repair

Fuse box
Under the seat, near the battery
Fuses
1
Battery access
Under the seat

Points ignition timing procedure (dual points, twin-cylinder)

  1. 01Remove the alternator inspection plate, ignition points cover, and ignition advance unit cover.
  2. 02Securely anchor the ignition advance weights into the fully retarded position (holding the weights inward) to check static timing first.
  3. 03Connect a point-checker (test light or continuity tester): black lead to a good ground, red lead to the grey point wire (right cylinder).
  4. 04Rotate the crankshaft in the normal running direction until the right-hand points just start to open, as indicated by the point checker.
  5. 05Check that the rotor timing mark lines up exactly between the two 'F' marks on the stator; if not, loosen the base plate lock screws and pivot the plate until the right-cylinder points open exactly at this position, then retighten.
  6. 06Switch the point-checker lead to the left-cylinder point wire (orange wire) and repeat the check/adjustment for the left-hand points independently, using their own smaller adjustment screws.
  7. 07Verify full-advance timing by wedging both advance weights fully open and rechecking that both cylinders' points open at the stator's full-advance mark (within a 3mm tolerance); if not, adjust the advance-weight stop tabs slightly.
  8. 08Reassemble all covers once both static and full-advance timing are confirmed correct.

Points gap adjustment

  1. 01Rotate the engine until the points cam lobe presents the point set to be adjusted at its fully open position.
  2. 02Loosen the points-plate retaining screw slightly, just enough to allow movement.
  3. 03Insert a 0.35-0.40mm (0.014-0.016in) feeler gauge between the contact points.
  4. 04Rotate the points assembly (using a screwdriver in the adjustment slot/lug) until the points close on the feeler gauge, then back off slightly until the gauge slides free with light drag.
  5. 05Tighten the retaining screw in this position.
  6. 06Repeat for the second point set (left cylinder), then verify final gap with the feeler gauge before replacing covers.

Valve clearance adjustment (screw-and-locknut rocker type)

  1. 01Remove the rocker box covers.
  2. 02Rotate the engine until the cylinder being checked is at top dead center on the compression stroke (verify by confirming both rockers on that cylinder have free play).
  3. 03Check clearance with a feeler gauge between the rocker tip and valve stem; loosen the 12mm locknut on the adjuster screw if clearance needs correction.
  4. 04Turn the adjuster screw in or out to achieve the specified clearance (varies slightly by model year and cylinder — verify against the specific factory table for intake vs. exhaust before adjusting), holding the screw steady while tightening the locknut.
  5. 05Recheck clearance with the feeler gauge after locking the nut, then repeat for the remaining valves in firing-order sequence.

Drive chain adjustment

  1. 01Place the motorcycle on its center stand with the rear wheel elevated.
  2. 02Check chain slack at the midpoint of the lower chain run against the factory spec of 20-30mm.
  3. 03Loosen the rear axle nut and both chain adjuster nuts at the swingarm ends.
  4. 04Turn each adjuster evenly on both sides, using the swingarm index marks to maintain wheel alignment, until correct slack is achieved.
  5. 05Re-tighten the rear axle nut to factory torque, then the adjuster lock nuts.
  6. 06Lubricate the chain, ideally while still warm from riding, for best penetration into the non-O-ring rollers.

Data sheet

Dimensions & weights

Wet weight
191 kg
Ground clearance
150 mm
Wheelbase
1435 mm

Engine & drivetrain

Engine
653 cc · Parallel twin
Cooling
Air cooled
Output
53 hp · 53 Nm
Transmission
5-speed
Final drive
Chain
Fuelling
Electronic fuel injection

Fuel & range

Fuel capacity
15 L
Real world range
250 km

Electronics & rider aids

Ride modes
None
Cruise control
No
Traction control
No
ABS
Yes
Heated grips
No
Heated seat
No

Service intervals

Service interval
5,000 km
Chain lube
every 500 km

Protection

Bash plate
None
Radiator guard
No
Oil cooler guard
No
Hand guards
No

Consumables & service specs

Every value carries its source.

Tyres

Front
3.50H-19 4PRYamaha XS650 Factory Service Manual (Scribd)
Rear
4.00H-18 4PRYamaha XS650 Factory Service Manual (Scribd)

Tyre pressures

Front — solo
1.6 kg/cm222 psi; normal riding, cold tyre, up to 90kg loadYamaha XS650 Factory Service Manual (Scribd)
Rear — solo
2.0 kg/cm228 psi; normal riding, cold tyre, up to 90kg loadYamaha XS650 Factory Service Manual (Scribd)
Front — loaded
2.0 kg/cm228 psi; with passenger or high-speed ridingYamaha XS650 Factory Service Manual (Scribd)
Rear — loaded
2.3 kg/cm232 psi; with passenger or high-speed ridingYamaha XS650 Factory Service Manual (Scribd)

Engine oil

Viscosity
Yamalube 4-cycle oil or SAE 20W-40 type SE motor oilYamaha XS650 Shop Manual (xs650chopper.com)
Capacity
2.0 lPeriodic oil change quantity; overhaul (full dry) fill is 2.5LYamaha XS650 Shop Manual (xs650chopper.com)

Brakes

Fluid type
DOT 3Front disc brake hydraulic system (rear drum brake on 1975 XS650B, no hydraulic fluid needed at rear)Yamaha XS650 Factory Service Manual (Scribd)

Forks

Oil viscosity
Yamaha fork oil 10Wt or equivalentYamaha XS650 Shop Manual (xs650chopper.com)
Oil capacity
164-172 mlPer front fork leg (5.54-5.82 oz)Yamaha XS650 Factory Service Manual (Scribd)

Final drive

Chain
SDHDS type, 103 links + joint, 15.875mm pitch (5/8in), 20-30mm free playNon-O-ring vintage chain type; free-play figure drawn from a later XS650H/SH-era supplement given general consistency of chain spec across the platform, flagged per _notes.sourceYearCaveatXS650H/SH Factory Supplement (xs650.de)

Spark plugs

Type
Champion N-7Y or NGK BP7ESXS650H/SH Factory Supplement (xs650.de)
Quantity
2Parallel-twin engine, one plug per cylinderYamaha XS650 Factory Service Manual (Scribd)

Battery

Type
12V lead-acid; later XS650H/SH supplement cites YB14L-A2 (Yuasa), 12V 14AH — presented as a reference figure for the platform given the same general electrical architecture, not confirmed 1975-specificXS650H/SH Factory Supplement (xs650.de)

Fuel

Minimum octane
90+ octane (period spec per XS650B owner's manual); modern equivalent 89-91 AKI mid-grade/premium1975-era XS650B owner's manual explicitly recommends fuel with a 90+ octane ratingYamaha XS650B Owner's Manual

What breaks first and where.

01

Middle (center) main bearing wear/failure

SeriousOccasional

The XS650's three-piece pressed crankshaft is supported by a center/middle main bearing (a roller-type bearing at the crank's mid-point) in addition to the outer main bearings. This bearing is widely and persistently discussed in the XS650 owner community as a long-term wear point, particularly on high-mileage engines, engines that have experienced oil starvation, or engines with worn oil pump components reducing lubrication pressure to the center bearing. Progressive wear can allow crankshaft flex/play, leading to increased vibration and, in advanced cases, more serious internal damage.

Symptoms

  • Increased engine vibration, especially noticeable as mileage accumulates
  • Lateral/axial play detectable in the crankshaft when checked at the alternator or clutch side
  • Metallic particles in oil at oil change
  • Knocking or clunking noise from the crankcase, especially under starter motor load

Field repairableNo — Diagnosis (checking for crankshaft lateral play) can be done without full engine removal, but the repair itself requires a full engine teardown and crankcase split to access and replace the center main bearing — not a roadside or field repair; typically undertaken as a planned rebuild.

XS650.com Forum — Crankshaft Lateral Movement