TGB BF8 - Page 43

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3. RELEASE AND INSTALLATION OF ENGINE
3-1 Starterd preparation data ＆ Simplified troubleshooting
※ Disassembling of Crankcase :
Before disassembling the crankcase, the engine must at first dismounted and the
following operations must be completed:
Air cleaner, carburettor, and air intake mounted◎ .
Starter motor.◎
Cylinder head cover, cylinder head.◎
Cylinder, piston.◎
Clutch cover, drive pully comp, driven pully comp.◎
Rear wheel, rear shock absorber.◎
Cooling fan, flywheel magneto.◎
Oil pump.◎
Standard preparation data for crank, cylinder, piston, and piston rings:
Unit: mm
125 c.c. Engine 151 c.c. Engine
Item Checking part
Standard value Allowable limit
Standard value
Allowable limit
Cylinder inner diameter 52.400-52.410 52.500 57.400-57.410 57.500
Roundness - 0.05 - 0.05
Cylinder
Cylinder degree - 0.05 - 0.05
Piston outer diameter 52.370-52.390 52.300 57.375-57.395 57.300
Inner diameter of piston pin 15.002-15.008 15.040 15.002-15.008 15.040
Gap between cylinder and piston
0.010-0.040 0.100 0.005-0.035 0.100
Top ring 0.015-0.055 0.090 0.015-0.050 0.090
Gap between
Piston and piston
ring
Second ring 0.015-0.055 0.090 0.015-0.050 0.090
Top ring 0.10-0.25 0.50 0.015-0.300 0.50
Second ring 0.10-0.25 0.50 0.015-0.300 0.50
Piston and
piston rings
Gap of piston ring
Lateral track of
oil scraper ring
0.2-0.7 - 0.2-0.9 -
Gap between piston and piston pin 0.002-0.014 0.020 0.002-0.014 0.020
Outer diameter of piston pin 14.994-15.000 14.960 14.994-15.000 14.960
Inner diameter of the hole at connectin
g
rod
small end
15.016-15.034 15.060 15.016-15.034 15.060
Blow with compressed air the parts after cleaning and before measuring.