Engine Specifications

Engine Specifications
Model(s)
750RL (Seca)
xjcdadmin Tue, 06/25/2013 - 15:02

A. ENGINE

Cylinder head: 

Volume 24,5 ±0.4 cm3 (1.49 ± 0.0244 cu.in)

Warp limit < 0.03 mm (0.0012 in)

 * Lines indicate straightedge measurement

Cylinder:

Material                                 Aluminum alloy with pressed-in sleeve

Bore size                             65 mm (2.56 in)

Taper limit                           < 0.05 mm (0.0020 in) >

Out-of-round limit              <0.01 mm (0.0004 in) >

Camshaft:

Drive method 
Chain drive (Center)  
Cam cap inside diameter

25+ 0.021-0 mm (0.984+008 -0in )

  
Camshaft outside diameter

25- 0.020-0.033 mm (0.984+008 -0.0013in )

 

  
Shaft-to-cap clearance Cam dimensions

0.020 ~ 0.054 mm (0.0008 ~ 0.0021 in)

Intake 'A" 36.8 mm (1.449 in)
  'B" 28.1 mm (1.106 in)
  •C" 8.8 mm (0.346 in)
Exhaust 'A" 36.3 mm (1.429 in)
  'B" 28.06 mm (1.105 in)
  •C" 8.3 mm (0.327 in)

Valve timing

T.D.C.

IN. Open                  B.T.D.C. 38

IN. Close                  A.B.D.C. 58°

EX. Open                  B.B.D.C. 56°

EX. Close                  A.T.D.C. 36°

Overlap                    a = 74°

Maximum runout: 0.06 mm (0.0024 in)

Cam chain type/Number of links BUSH-CHAIN/120
Cam chain adjustment method Automatic

 

Valve, Valve seat, Valve guide:

        
Valve clearance (Cold) IN. 0.11 - -0.15mm (0.0043- - 0.0059 in)
  EX. 0.16- - 0.20 mm (0.0063 - - 0.0079 in)

Valve dimensions

"A" Head dia. IN. 34 ±0.1 mm (1.34 ± 0.004 in)
  EX. 28 ±0.1 mm (1.10 ± 0.004 in)

"B" Face width IN. 2.3 mm (0.091 in)
  EX. 2.3 mm (0.091 in)

"C" Seat limit width IN. 1 +0.1 mm (0.039 ± 0.004 in)
  EX. 1 ±0.1 mm (0.039 ± 0.004 in)

"D" Margin thickness limit IN. 1.2 + 0.2 mm (0.0472 ± 0.008 in)
  EX. 1.0 ± 0.2 mm (0.0394 ± 0.008 in)
Stem outside diameter IN. 7 -0010-0.025mm (0.2756-0.0004 -0.0010 in) 
  EX. 7 -0025-0.040mm (0.2756-0.0010 -0.0016 in
Guide inside diameter IN. 7+0.012 -0mm(0.2756 +0.0005 -0in)
  EX. 7+0.012 -0mm(0.2756 +0.0005 -0in)
Stem-to-guide clearance IN. 0.010 ~ 0.037 mm (0.0004 ~ 0.0015 in)
  EX. 0.025 ~ 0.052 mm (0.0010 ~ 0.0020 in)
Stem runout limit   < 0.03 mm (0.0012 in) >

Valve seat width standard 0.9-1.1 mm (0.035 ~ 0.043 in)
< Limit > < 2.0 mm (0.080 in) >
Valve spring:      
Free length      
Inner spring IN. EX. 35.9 mm (1.413 in) 35.9 mm (1.413 in)  
Outer spring IN. EX. 39.5 mm (1.555 in) 39.5 mm (1.555 in)  
Spring rate      
Inner spring IN. K1 : 2.36 kg/mm (132 lb/in) K2 : 1.84 kg/mm (103 lb/in)
  EX. K1 : 2.36 kg/mm (132 lb/in) K2 : 1.84 kg/mm (103 lb/in)
Outer spring IN. K1 : 4.58 kg/mm (256 lb/in) K2 : 3.464 kg/mm (194 lb/in)
  EX. K1 : 4.58 kg/mm (256 lb/in) K2 : 3.464 kg/mm (194 lb/in)
Compression length (Valve closed)      
Inner spring IN. EX. 31.0 mm (1.220 in)
31.0 mm (1.220 in)		  
Outer spring IN. EX. 34.0 mm (1.339 in)
34.0 mm (1.339 in)		  
Compression force (Valve closed)      
Inner spring IN. EX. 8.1 ~9.9 kg (17.9-21.8 lb)
8.1 -9.9 kg (17.9-21.8 lb)		  
Outer spring IN. EX. 17.6-20.6 kg (38.8-45.4 lb)
17.6-20.6 kg (38.8-45.4 lb)		  

Tilt limit
Inner spring IN. & EX. 2.5 /1.7 mm (0.067 in)
Outer spring IN. & EX. 2.5°/1.7mm (0.067 in)

Direction of winding (Top view)

Intake

Exhaust

Piston:

Piston size/Measuring point (A)

65.0 mm (2.559 in)/7.8 mm (0.307 in) (From bottom line of piston skirt)

Clearance between piston & Cylinder 0.03 ~ 0.05 mm (0.0012 ~ 0.0020 in)
Oversize 1 st -
2nd 65.50 mm (2.579 in)
3rd —
4th 66.00 mm (2.598 in)
Piston pin hole off-set 0.5 mm (0.02 in) inside

Piston ring:

Sectional sketch

Top ring  

D 1,-0.01mm/nn>n,-0.0004i > B 1-2 -0.03 mm <0-0472-0.0012 m)
  T = 2.7 ± 0.1 mm (0.106 ± 0.004 in)
2nd ring B=1.2:^mm(0.0472Z°Sin)
  T = 2.7 + 0.1 mm (0.106 ± 0.004 in)
Oil ring B = 2.5 mm (0.098 in)
  T = 2.8 ± 0.15 mm (0.110 ± 0.0059 in)

 

End gap (Installed) Top ring 0.15 ~ 0.35 mm (0.0059 ~ 0.0138 in)
Limit   < 1.0 mm (0.039 in) >
  2nd ring 0.15 ~ 0.35 mm (0.0059 ~ 0.0138 in) < 1.0 mm (0.039 in) >
  Oil ring 0.3 ~ 0.9 mm (0.012 ~ 0.035 in) < 1.5 mm (0.059 in) >
Side clearance    
Limit Top ring 0.03 ~ 0.07 mm (0.0012 ~ 0.0028 in) < 0.15 mm (0.0059 in) >
  2nd ring 0.02 ~ 0.06 mm (0.0008 ~ 0.0024 in) < 0.15 mm (0.0059 in) >
Plating or coating   
Top ring  
Chrome plated, Ferox coating
  2nd ring Chrome plated, Ferox coating
  Oil ring Chrome plated, Ferox coating

Connecting rod:
Oil clearance 0.016 ~ 0.040 mm (0.0006 ~ 0.0016 in)
Color code 1. Blue, 2. Black, 3. Brown, 4. Green

Crankshaft:

Assembly width "B" 341.4 ± 0.6 mm (13.44 ± 0.024 in)
Deflection limit "C" < 0.03 mm (0.0012 in) >
Big end side clearance "D" 0.16 ~ 0.26 mm (0.0063 ~ 0.00102 in)
Journal oil clearance 0.020 ~ 0.044 mm (0.0008 ~ 0.0017 in)
Color code — corresponding size Blue 1.5 +0.008 +0.002 mm (0.0591 +0.00024 +0.00008
  Black 1.5 +0.002 -0.002 mm (0.0591 +0.00008 -0.00008
  Brown 1.5 -0.002 -0.006 mm (0.0591 -0.0008 -0.00024
  Green 1.5 -0.006 -0.010 mm (0.0591 -0.00024 -0.00039
  Yellow 1.5 -0.010 -0.014 mm (0.0591 -0.00039 -0.00055
Clutch:  
Friction plate thickness/Quantity 3.0 ± 0.1 mm (0.12 ± 0.004 in)/8
Wear limit < 2.8 mm (0.11 in) >
Clutch plate thickness/Quantity 2.0 ± 0.1 mm (0.080 ± 0.004 in)/7
Warp limit < 0.05 mm (0.002 in) >
Clutch spring free length/Quantity 42.8 mm (1.685 in)/5
Minimum length 41.8 mm (1.622 in)
Primary reduction gear backlash tolerance 120
Primary drive gear  
Backlash numer 87~93
Primary driven gear  
Backlash numer 25~31
Clutch release method Rack & Piston pull, Outer pull
Transmission:  
Main axle run-out limit 
< 0.08 mm (0.0031 in) >
Shifter:  
Shifter type Guide bar

Carburetor:

Type/manufacturer/quantity

 HSC33-11/HITACHI/4

I.D. mark

 41Y00

Throttle Valve Size

 12.5°
Main jet (M.J.) #106
Main air jet (M.A.J.) #70
Jet needle UN.) Y-18
Pilot jet (P.J.) #40
Pilot air jet (P.A.J.) #225
Pilot screw (turns out) (P.S.) Pre-set
Pilot outlet size (P.O.) Φ 0.9
Starter jet (G.S.) #43
Valve seat size (V.S.) Φ 2.0
Fuel level (F.L.) 1.0 ±1 mm (0.0394 ± 0.039 in)

Engine idling speed

 1,100 ± 50 r/min

Vacuum pressure at idling speed

 180mmHg (7.09 inHg)
Lubrication system:  
Oil filter type Paper filter
Oil pump type Trochoid pump
Tip clearance 0.03 ~ 0.09 mm (0.0012 ~ 0.0035 in)
Side clearance 0.03 ~ 0.08 mm (0.0012 ~ 0.0031 in)
Bypath valve setting pressure 98 ± 20 kPa (1.0 ± 0.2 kg/cm2, 14.2 ± 2.8 psi)
Relief valve operating pressure 490 + 50 kPa (5.0 ± 0.5 kg/cm2, 71.1 + 7.1 psi)
Lubrication diagram  

Middle gear backlash 0.1 - ~ 0.2 mm (0.004 - - 0,008 in)
Final gear backlash 0.1 - -0.2 mm (0.004- - 0.008 in)

Crankcase tightening sequence

LOWER CASE

UPPER CASE

Tightening Torque:

8 mm bolt: 24 Nm (2.4 m-kg, 17ft-lb)  6 mm bolt: 12 Nm (1.2 m-kg, 8.7 ft-lb)

 

Engine fastener Tightening Torque

 

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks
Nm mkg ft lb

ENGINE:

Camshaft cap

 Bolt M6x1.0 24

10     1.0    7.2

 Tighten in stages

Cam chain (Front) (Rear)

 Stud bolt Nut

Stud bolt Nut

 M6x1.0
M6x1.0
M6x1.0
M6x1.0		 2
2
2 2

5 0.    5         3.6

10      1.0      7.2
5       0.5       3.6
10      1.0      7.2

 Apply oil Apply oil

Exhaust pipe

 Stud bolt M6x1.0 8

8       0.8       5.8

 Apply oil

Oil passage blind plug

 Screw M6x1.0 1

7       0.7       5.1

  

YICS passage

 Stud bolt
Nut
Blind plug		 M8x1.25
M8x1.25
M12x1.25		 2

2 2

15      1.5       11
20      2.0       14
22      2.2       16

 Apply oil

Spark plug

 — M14X1.25 4

20      2.0       14

  

Cylinder head

 Nut M10x1.25 12

32      3.2       23

 Apply oil

Cylinder head cover

 Bolt M6x1.0 8

10      1.0      7.2

  

Cam chain (Cylinder-Front)

 Stud bolt

Nut

 M8x1.25
M8x1.25		 1

1

8        0.8      5.8
20      2.0       14

 Apply oil

Connecting rod

 Nut M8x0.75 8

38      3.8       27

 Apply Molybedenum
disulfide grease

Cam sprocket

 Bolt M7x1.0 4

20      2.0       14

  

Cam chain tensioner

 Bolt M6x1.0 2

10      1.0      7.2

  

Cam chain tensioner guide

 Bolt M8x1.25 1

3        0.3     2.2

  

Oil Pump cover

 Screw M6x1.0 4

7        0.7      5.1

  

Strainer housing

 Screw M6x1.0 3

7        0.7      5.1

  

Oil pump

 Bolt M6x1.0 3

12      1.2      8.7

  

Oil filter

 Union bolt M20x1.5 1

15      1.5      11

  

Engine drain bolt

 Bolt M14x1.5 1

43      4.3      31

  

Strainer cover

 Bolt M6x1.0 13

12      1.2      8.7

  

Oil pump sprocket

 Bolt M6x1.0 1

12      1.2      8.7

  

Buffle plate

 Screw M6x1.0 3

7        0.7      5.1

  

Oil cooler adapter plate

 Union bolt M20x1.5 1

50      5.0       36

  

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks
Nm mkg ft-lb
Oil cooler hose and adapter Bolt M6x1.0 4 12 1.2 8.7  
Oil hose Bolt M6x1.0 1 12 1.2 8.7  
Oil cooler Bolt M6x1.0 3 10 1.0 7.2  
Oil cooler hose clamp Nut M8x1.25 1 10 1.0 7.2  
Carburetor joint Bolt M6x1.0 8 12 1.2 8.7  
Air filter case cover Screw M6xt.O 4 5 0.5 3.6  
Air filter case and frame Bolt M6x1.0 3 5 0.5 3.6  
Exhaust pipe joint band Bolt M8x1.25 6 20 2.0 14  
Exhaust pipe ring nut Nut M6x1.0 8 10 1.0 7.2  
Exhaust pipe and frame Bolt M1 0x1.25 2 25 2.5 18  
Cylinder Stud bolt Bolt M10x1.25 M10X1.25 8

4

 20 20 2.0 2.0 14

14

  
Crankcase Bolt Bolt M8x1.25 M6x1-0 19

19

 24

12

 2.4 1.2 17 8.7  
Bearing plate stopper Screw M8x1.25 4 25 2.5 18  
Breaker cover Screw M6x1.0 8 8 0.8 5.8  
Generator cover . Bolt M6x1.0 3 12 1.2 8.7  
Generator housing bearing Screw M6x1.0 3 10 1.0 7.2  
Change cover Bolt M6x1.0 10 12 1.2 8.7  
Drive shaft housing bearing Bolt M6x1.0 3 12 1.2 8.7  
Clutch cover Bolt M6x1.0 10 12 1.2 8.7  
Clutch cable holder Bolt M6x1.0 2 12 1.2 8.7  
Middle drain bolt Bolt M8x1.25 1 16 1.6 11  
Breather pipe 1 Screw M6x1.0 3 7 0.7 5.1  
Breather pipe 2 Screw M6x1.0 4 7 0.7 5.1  
Main gallary blind plug Plug M20X1.5 2 12 1.2 8.7 Apply oil
Stopper plate Bolt M6x1.0 1 10 1.0 7.2  
Clutch starter outer Bolt M8x1.25 3 25 2.5 18  
Upper guide Bolt M6x1.0 3 10 1.0 7.2  
Clutch pressure plate Bolt M6x1.0 5 8 0.8 5.8  
Clutch boss Nut M20X1.0 1 70 7.0 50  
Drive shaft bearing Nut M34x1.0 1 110 11.0 80  

Part to be tightened

Part name

Thread size

Q'ty

Tightening torque

Remarks
Nm mkg ft ib
Driven shaft bearing Nut M65x1.5 1 110 11.0 80  
Middle gear flange Nut M14x1.5 1 90 9.0 65  
Housing bearing Bolt M8x1.25 4 25 2.5 18  
Stopper plate Screw Bolt M6x1.0 M6x1.0 1

1

 7 8 0.7 0.8 5.1 5.8  
Change pedal Bolt M6x1.0 1 10 1.0 7.2  
Change pedal link Nut M6x1.0 2 10 1.0 7.2  
A.C. Generator Bolt M10x1.25 1 55 5.5 40  
Pick-up coil base Screw M6x1.0 2 8 0.8 5.8  
Rotor Bolt M8x1.25 1 24 2.4 17  
Brush Screw M6x1.0 2 8 0.8 5.8  
Timing plate Screw M6x1.0 1 8 0.8 5.8  
Starter motor Bolt M6x1.0 2 7 0.7 5.1  
Oil level switch Bolt M6x1.0 2 7 0.7 5.1  
Drive shaft U Nut M14x1.5 1 110 11.0 80  
Bearing cap Bolt Nut M10x1.25 M8x1.25 2

6

 23 23 2.3 2.3 17

17

  
Oil mount screw Plug M14x1.5 1 23 2.3 17  
Oil drain screw Plug M14x1.5 1 23 2.3 17  
Bearing retainer — M65x1.5 1 110 11.0 80  
Final gear case Stud bolt Stud bolt M10x1.25 M8x1.25 4

6

 17 9 1.7

0.9

 12 6.5