SERVICE INFORMATION
GX340
Unit: mm (in)
Valves Valve clearance IN 0.15 ± 0.02 –
EX 0.20 ± 0.02 –
Valve stem O.D. IN 6.575 – 6.590 (0.2589 – 0.2594) 6.44 (0.254)
EX 6.535 – 6.550 (0.2573 – 0.2579) 6.40 (0.252)
Valve guide I.D. IN/EX 6.600 – 6.612 (0.2598 – 0.2603) 6.66 (0.262)
Guide-to-stem
clearance
IN 0.010 – 0.037 (0.0004 – 0.0015) 0.10 (0.004)
EX 0.050 – 0.077 (0.0020 – 0.0030) 0.12 (0.005)
Valve seat width 1.0 – 1.2 (0.04 – 0.05) 2.0 (0.08)
Valve spring free length 39.0 (1.54) 37.5 (1.48)
Valve spring perpendicularity – 1.5° max.
Camshaft Cam height IN 31.945 – 32.145 (1.2577 – 1.2655) 31.35
(1.234)
EX 31.666 – 31.866 (1.2467 – 1.2546) 31.35
(1.234)
Camshaft O.D. 15.966 – 15.984 (0.6286 – 0.6293) 15.92
(0.627)
Carburetor Main jet #88 –
Pilot screw opening BE21J A: 2 turns out –
Float height 13.2 (0.52) –
Spark plug Gap 0.7 – 0.8 (0.028 – 0.031) –
Ignition coil Air gap 0.2 – 0.6 (0.01 – 0.02) –
Starter motor Brush length 7.0 (0.28) 3.5 (0.14)
Mica depth 1.0 (0.04) 0.2 (0.01)
Charge coil Resistance 1A 3.00 - 4.00 ȍ –
3A 0.62 - 0.93 ȍ –
10A 0.16 - 0.24 ȍ –
18A 0.10 - 0.30 ȍ –
Lamp coil Resistance 12V - 15 W 1.04 - 1.56 ȍ –
12V - 25 W 0.30 - 0.46 ȍ –
12V - 50 W 0.29 - 0.44 ȍ –
Part Item Standard
Service
limit
Part Item Standard
Service
limit
Engine Maximum speed (at no load)
3,850 ± 150 min
-1
(rpm)
–
Idle speed
1,400 ± 150 min
-1
(rpm)
–
Cylinder compression
0.51 - 0.69 MPa (5.2 - 7.0 kgf/cm
2
,
74 - 100 psi) / 600 min
-1
(rpm)
–
Cylinder head Warpage – 0.10 (0.004)
Cylinder Sleeve I.D. 88.000 – 88.017 (3.4646 – 3.4652) 88.170
(3.4713)
Piston Skirt O.D. 87.965 – 87.985 (3.4632 – 3.4640) 87.85(3.459)
Piston-to-cylinder clearance 0.015 – 0.052 (0.0006 – 0.0020) 0.12 (0.005)
Piston pin bore I.D. 20.002 – 20.008 (0.7875 – 0.7877) 20.042
(0.7891)
Piston pin Pin O.D. 19.994 – 20.000 (0.7872 – 0.7874) 19.950
(0.7854)
Piston pin-to-piston pin bore clearance 0.002 – 0.014 (0.0001 – 0.0006) 0.08 (0.003)
Piston rings Ring side clearance Top 0.030 – 0.060 (0.0012 – 0.0024) 0.15 (0.006)
Second 0.030 – 0.060 (0.0012 – 0.0024) 0.15 (0.006)
Ring end gap Top 0.200 – 0.350 (0.0079 – 0.0138) 1.0 (0.04)
Second 0.350 – 0.500 (0.0138 – 0.0197) 1.0 (0.04)
Oil (side rail) 0.2 – 0.7 (0.01 – 0.03) 1.0 (0.04)
Ring width Top 1.160 – 1.175 (0.0457 – 0.0463) 1.140
(0.0449)
Second 1.160 – 1.175 (0.0457 – 0.0463) 1.140
(0.0449)