SPECIFICATION SHEET
MACHINE SPEC.
Type SUZUKI HM31A
Length 2,100mm
Width 695mm
Hight 1,185mm
Wheel base 1,425mm
Emgine type M301
Weight, Front 87kgs
Weight, Rear 91kgs
Weight, Total 178kgs
ENGINE
Bore x Stroke 56.0 x 50.6
Compression ratio 7
Compression pressure 8.0kg/cm2/rpm
Weight (inc. Transmission) 50kgs
Intake open 145o BTDC
Intake close 55o ATDC
Exhaust open 90o BBDC
Exhaust close 90o ABDC
Scavenge open 60o BBDC
Scavenge close 60o ABDC
Idoling r.p.m. 1,500
TRANSMISSION
Primary gear ratio 2.23
Clutch facing size 132 x 111 x 2.8
Clutch facing Area x Piece 34 x 8
Transmision Gear ratio 1st 2.636
Transmision Gear ratio 2nd 1.750
Transmision Gear ratio 3rd 1.380
Transmision Gear ratio 4th 1.173
Transmision Gear ratio 5th 1.045
Transmision Gear ratio 6th 0.956
Final gear ratio 2.50 (16/41T)


MAINTENANCE DATE
PISTON/CYLINDER
Item Standard Limit
Clearance, Piston/Cylinder 0.05~0.06 0.12
Inner dia., Cylinder 56.0~56.05 56.65
Outer dia., Piston (25mm from lower end) 55.93~55.945 55.88
Surface level, Cylinder head 0~0.03 0.15
Free gap, Piston ring (1st) 4.7 3.76
Free gap, Piston ring (2nd) 4.7 3.76
Assembled gap, Piston ring (1st) 0.15~0.30 0.75
Assembled gap, Piston ring (2nd) 0.15~0.30 0.75
Clearance, Piston ring/Ring slot (1st) 0.03~0.09 -
Clearance, Piston ring/Ring slot (2nd) 0.02~0.06 -
Inner dia., Piston pin hole 14.002~14.010 14.034
Compression (kg/cm2) 8 5.6
Compression difference between each cylinder (kg/cm2) - 1 kg/cm2
CRANK SHAFT
Item Standard Limit
Outer dia., Piston pin 13.995~14.000 13.965
Inner dia., Con-Rod Small end 18.003~18.011 18.039
End-Play, Con-Rod Small end - 3
Thrust gap, Con-Rod Small end 0.2~0.62 1
Thrust gap, Con-Rod Big end 0.2~0.9 1
End-Play, Crank shaft 0~0.05 0.08
OIL PUMP
Item Standard
Oil consumpsion (Oil pump full open, 2,000r.p.m., 2 min.) 7.1~7.6 cc
Adjust method, Oil pump control lever Center mark
CLUTCH/PRIMARY GEAR
Item Standard Limit
Free play, Clutch lever 10~15
Thicness, Drive plate 2.8 2.5
Strain, Drive plate 0~0.25 0.4
Thicness, Driven plate 1.54~1.66 -
Strain, Driven plate 0~0.1 0.2
Free length, Clutch spring 35.8 34.01
Primary gear backrush 0.05
TRANSMISSION
Item Standard Limit
Thickness, Gear shift fork (1) 4.8~4.9 -
Thickness, Gear shift fork (2) 4.8~4.9 -
Thickness, Gear shift fork (3) 4.8~4.9 -
Width, Gear shift fork groove (1) 5.0~5.1 -
Width, Gear shift fork groove (2) 5.0~5.1 -
Width, Gear shift fork groove (3) 5.0~5.1 -
Gap, Gear shift fork/Groove (1) 0.1~0.3 0.5
Gap, Gear shift fork/Groove (2) 0.1~0.3 0.5
Gap, Gear shift fork/Groove (3) 0.1~0.3 0.5
Bend, Shift fork shaft 0~0.03 0.05
CARBULATOR
Item Standard
Carbulator type VM28
Main bore 28
Idoling r.p.m. 1,500
Fuel level 5.5
Main jet (M.J.) 120
Jet needle (J.N.) 5CM1-2
Needle jet (N.J.) P-5
Throttle valve (C.A.) 2.5
Pilot jet (P.J.) 25
Air screw (A.S.) 1-5/8
Valve seat (V.S.) 2.5
Starter jet (G.S.) 50




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