Specifications

1. OESCRIPTION
1 I Engine type Air cooled, 4.stroke. SOHC twin,
parallel forward incline
21 Engine model
2FO
31 Displacement 653 cc (39.85 cu.in)
41 Bore x stroke 75 x 74 mm (2.953 x 2.913 in)
51 Compression ratio 8.5 : I
61 Starting system. Kick and electric starter
7) Ignition system Battery ignition
81 Lubrication system wet sump
2. CYLINDER HEAD
1 I Combustion chamber volume (with N-7Yl 43.6 cc (2.660 win)
21 Combustion chamber type
Dome + Squish
31 Head gasket thickness 1.2 mm (0.047 in)
3. CYLINDER
1 I Material
Aluminum alloy with cast iron sleeve
2) Bore size
31 Taper limit
~ ~~~~~~l”,,o~~irj:.9528 +~.Ooos in)
41 Out of round limit
0.01 mm (0.0004 in)
1. PISTON I
1) Piston skirt clearance 0.050 - 0.055 mm ~0.0020 - 0.0022 in)
21 Piston oversize 75.25 mm 75.50 mm 75.75 ml-n 76.00 mm
12 963 in, 12972 in, 12982 in, 12992 InI
3) Piston pin outside diameter x length
20.0 _;,, mm x 61 .o
-:.a mm
IO.79 &,,,, in x 2.40
-&II 16 j”)
5. PISTON RING
11 Piston ring design
TOI,
2nd
Oil ring
-@ -I% -+.a%
1.2 mm 10.047 in) 1.5 mm 10.059 in, 2.8 mm 10.110 II
21 Ring end gap IInstalled. top) 0.2 - 0.4 mm (0.008 - 0.016 in)
ilnrtalled. 2nd) 0.2 - 0.4 mm (0.008 - 0.016 in)
(Installed. oil) 0.3 - 0.9 mm (0.012 - 0.035 in1
3) Ring groove side clearance (Top) 0.04 - 0.08 mm (0.0016 - 0.0031 in)
(2nd) 0.03 - 0.07 mm (0.0012 - 0.0028 in)
6. BIG END BEARING
1) Tvpe
Needle bearing
2) Bearing size
@26x @34x19.8
31 Needle size @4x ~15.6x13
7. CAMSHAFT
1 I Cam drive type Chain (Center side)
21 Number and type of bearing 4 bearings, Ball bearings (6W5)
31 Bearing type
Q25-647-8
41 Cam dimensions
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