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Stock YSR Specs


Length 1,630 mm 64.2 in
Width 635 mm 25.0 in
Height 930 mm 36.6 in
Seat Height 660 mm 25.6 in
Wheel Base 1,055 mm 41.5 in
Min. Ground Clearance 120 mm 4.7 in
Weight w/ Oil & Fuel 91 kg 210 lbs
Weight w/o Oil & Fuel 165 lbs
Fuel Capacity 2.11 gallons
Min. Turning Radius 2,400 mm 94.5 in


Type Air Cooled, Single, 2-Stroke
Displacement 49.3 cc
Bore/Stroke 40.0 X 39.2 mm 1.57 X 1.54 in
Compression Ratio 7.4:1
Max. Torque 4.27 ft. lbs.@8,500 rpm
Ignition CDI
Starting System Kick Starter
Induction System Reed valve
Carburetion Mikuni VM16SH
Air Filter Wet type element
Lubrication System Yamaha Autolube
Oil Tank Capacity .73 L .77 US qt
Oil Type Yamalube 2 or BIA cert. for service TC-W
Transmission Oil Capacity .65 L .69 US qt
Periodic Trans. Oil Change .60 L .63 US qt
Transmission Oil Type Yamalube 4 or SAE 10W30 Type SE or GL gear oil
Transmission 5 Speed


Type Constant mesh 5-speed
Primary Reduction System Helical gear
Primary Reduction Ratio 68/19 3.579
Secondary Reduction System Chain drive
Secondary Reduction Ratio 44/12 3.667
Operation Left foot operation
Gear Ratio 1st 39/12 3.250
Gear Ratio 2nd 34/17 2.000
Gear Ratio 3rd 30/21 1.429
Gear Ratio 4th 27/24 1.125
Gear Ratio 5th 25/26 0.962


Type Wet, multiple disc


Type VM16SH
Manufacturer Mikuni
Main Jet #120
Pilot Jet #17.5
Starter Jet #20
Air Jet 2.5
Jet Needle-Position 3G21-4
Needle Jet E-0
Cutaway 2.0
Pilot Outlet 0.9
Air Screw 1-1/8
Valve Seat Size 1.5
Fuel Level 0~1 / 0~0.04"
Float Height 21~23mm / 0.83~0.91"
Idle Speed 1,300~1,400 rpm

Spark Plug

Type B7HS or B8HS
Manufacturer NGK
Manufacturer 0.5~0.6mm / 0.020~0.024"

Reed Valve

Valve Thickness 0.15mm 0.006"
Valve Stopper Height 6.7~7.3mm 0.26~0.29"
Valve Bending Limit 0.3mm 0.012"


Front Telescopic Fork
Rear Monoshock


Front Type Single disc
Front Disc Outside Diameter 203mm 8.00"
Front Disc Thickness 4.0mm 0.16"
Front Brake Pad 6.0mm 0.24"
Front Pad Wear Limit 0.5mm 0.02"
Master Cylinder Inside Diameter 11.0mm 0.433"
Caliper Cylinder Inside Diameter 34.9mm 1.37"
Brake Fluid Type DOT #3
Rear Type Drum
Drum Inside Diameter 110mm 4.33"
Drum Wear Limit 111mm 4.37"
Lining Thickness 4mm 0.16"
Lining Wear Limit 2mm 0.08"


Front 3.50 X 12
Rear 4.00 X 12


Frame Type Double cradle
Caster Angle 25.3°
Trail 64mm ~ 2.52"


Type 420M
No. Links 99 Links + Master link
Free Play 25~30mm / 1.0~1.2"


Spark Plug 18 ft lb
Cylinder Head 7.2 ft lb
Intake Manifold 5.8 ft lb
Muffler (Front) 5.8 ft lb
Muffler (Rear) 13 ft lb
Crankcase 5.8 ft lb
Crankcase Cover 7.2 ft lb
Transmission Drain Bolt 14 ft lb
Primary Drive Gear 43 ft lb
Clutch Boss 32 ft lb
Pressure Plate 4.3 ft lb
Shift Lever Adj. Nut 18 ft. lb
Change Pedal 8 ft lb
Stator 5.8 ft lb
CDI Magneto 50 ft lb
Neutral Switch 2.9 ft lb
Engine Mount 18 ft lb
Engine Stay 18 ft lb
Rear Shock 29 ft lb
Front Fork Cap 40 ft lb
Lower Triple Clamp 22 ft lb
Steering Ring Nut 4.3 ft lb
Steering Stem Bolt 29 ft lb
Wheel Hub & Rim 22 ft lb
Front Brake Disc 14 ft lb
Brake Caliper 25 ft lb
Front Axle & Nut 29 ft lb
Rear Sprocket & Hub 25 ft lb
Rear Axle & Nut 43 ft lb


1987 White/Red
1988 White/Red or Blue/Yellow
1989 White/Red or Blue/Yellow
1990 White/Red
1991 White/Red or Black/Yellow
1992 White/Red or Black/Yellow

If there is a specification not listed here that you require E-mail me.

Other Racer4YSR sites to check out

Racer4YSR's Home Page...Back to Jim's home page
A-Tak Force Racing Team...Our 6 time championship racing team
Racer4YSR's Race Results...Latest races results & locations
Racer4YSR's Picture Page...Various pictures of me racing
Racer4YSR's Links...A few motorcycle links
Racer4YSR's Multiple Myeloma Cancer...My fight with cancer
Bro's/Team mate Home Page...Jason's home page
Bro's/Team mate Racing Page...Jason's Racing Page
The Right Line...South West Association of Road Racing Teams
Kamikazi Cole's YSR Page...YSR racer from Las Vegas
MiniMoto Madness...Pocketbikes & YSR's. Parts, Service, New & Used bikes for sale.

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Created on Apr.22,1999

Last updated on Mar.18,2000

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