1. Small Gas Engine Parts Identification Four-Stroke Cycle
By Dave Wilson
Information Technology and Communication Services
ITCS Instructional Materials
University of Illinois
Urbana-Champaign
Copyright ® 2010 University of Illinois Board of Trustees

2. Introduction Previous Slide Contents Next Slide
To view individual carburetor parts, a table of contents with links is provided in frames 4 and 5. To view the individual parts, the user may click on the part name from the table of contents, and the link will navigate to the part. Clicking the Contents button will return the user to the table of contents.
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3. Introduction
Knowing the parts of an engine is one of the first steps to learning engine repair and maintenance. Repair technicians gain confidence in themselves, and their customers gain confidence in them when they identify parts using the jargon of the industry. Another function of learning engine parts is to communicate with customers, other technicians, parts providers, and manufacturers using terms that are equally understood. Using universally understood terms promotes efficiency within the industry.
It is important to understand the relationship between engine parts to gain an understanding of how an engine works. Additionally, understanding how an engine works is key to diagnosing an engine problem. Diagnostic skills are a learned talent, and it requires practice to improve their application with efficient repair and maintenance of small gas engines.

4. Table of Contents Quit Slide Slide Oil ring with expander …………… 27
Piston pin or wrist pin …………….
Piston pin locks …………………...
Connecting rod ……………………
Connecting rod screws with piston
assembly …………………..………………
Exhaust valve ……………………..
Intake valve ……………………….
Valve spring ……………………….
Valve retainer ……………………..
Valve tappet ……………………….
Camshaft …………………………..
Intake manifold ……………………
Intake manifold gasket …………...
Rewind starter housing …………..
Starter rope with starter housing ………
Starter rope grip …………………..
Mechanical governor link with spring
Governor control lever ……………
Governor shaft (crank) with retainer .
Oil slinger/governor ……………… 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
Cylinder assembly with head gasket …
Oil seal (magneto end).. …………..
Engine sump or crankcase cover ..
Cylinder head with head bolts ………….
Head gasket ………………………..
Breather gasket ……………………
Breather assembly ………………...
Breather tube ………………………
Crankcase gasket …………………
Cylinder head bolts ……………….
Oil drain plug ……………………….
Crankshaft ………………………….
Oil seal (PTO end) ………………...
Crankcase cover screw …………..
Flywheel …………………………….
Flywheel key ……………………….
Piston ……………………………….
Top compression ring with piston ……
Center compression ring and piston . 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26

5. Table of Contents Quit Slide Slide Oil dipper ……………………………
Dipstick with dipstick tube ………………...
Magneto armature …………………
Spark plug ………………………….
Stop wire attached to flywheel brake ……
Brake assembly ……………………
Air filter …………..………………….
Flywheel cup with nut ……………………
Blower housing (shroud) ………….
Cylinder shield ……………………..
Breather passage cover with gasket .
Timing gear …………………………
Muffler with mounting screws and lock ….
Muffler guard ……………………….
Muffler deflector ……………………
O-ring seal ………………………….
Fuel tank cap ………………………. 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
Air cleaner base ………………….
Air cleaner cover …………………
Fuel line with hose clamps …………….
Fuel tank with cap ………………………
Control bracket …………………..
Carburetor ………………………..
Push rod ………………………….
Flywheel nut ……………………...
Cover, overhead valve engine …
Overhead valve engine head …..
Rewind guard …………………….
Exhaust gasket ………………….. 64 65 66 67 68 69 70 71 72 73 74 75 76
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6. Cylinder assembly with head gasket

7. Oil seal (magneto end)

8. Engine sump or crankcase cover

9. Cylinder head with head bolts

10. (cylinder head gasket)

11. Breather gasket

12. Breather assembly

13. Breather tube

14. Crankcase gasket

15. Cylinder head bolts

16. Oil drain plug

17. Oil drain plug

18. Oil drain plug

19. Crankshaft

20. Oil seal (PTO end)
PTO = Power Take Off

21. Crankcase cover screw

22. Flywheel

23. Flywheel key

24. Piston

25. Top compression ring with piston

26. Center compression ring and piston

27. Oil ring with expander

28. Piston pin or wrist pin

29. Piston pin locks

30. Connecting rod

31. Connecting rod screws with piston assembly

32. Exhaust valve

33. Intake valve

34. Valve spring

35. Valve retainer

36. Valve tappet

37. Camshaft

38. Intake manifold

39. Intake gasket

40. Rewind starter housing

41. Starter rope with starter housing

42. Starter rope grip

43. Mechanical governor link with spring

44. Governor control lever

45. Governor shaft (crank) with retainer

46. Oil slinger/governor

47. Oil dipper

48. Dipstick with dipstick tube

49. Magneto armature

50. Spark plug

51. Stop wire attached to flywheel brake

52. Brake assembly

53. Air filter

54. Flywheel cup with nut

55. Blower housing (shroud)

56. Cylinder shield

57. Breather passage cover with gasket

58. Timing gear

59. Muffler with mounting screws and lock

60. Muffler guard

61. Muffler deflector

62. O-ring seal

63. Fuel tank cap

64. Air cleaner base

65. Air cleaner cover

66. Fuel line with hose clamps

67. Fuel tank with cap

68. Control bracket

69. Carburetor

70. Push rod

71. Push rod

72. Flywheel nut

73. Cover, overhead valve engine

74. Overhead valve engine head

75. Rewind guard

76. Exhaust gasket

77. University of Illinois
End of show
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This material was prepared by Dave Wilson, Information Technology and Communication Services, and reviewed by Dr. Joe Harper, Department of Agricultural and Biological Engineering, College of Agricultural, Consumer and Environmental Sciences, University of Illinois at Urbana-Champaign. Photographs by the author.
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