Here's a collection of the kinds of things lifelong, professional mechanics don't believe and that make them laugh when forum "experts" espouse them. I'm sure you'll find these insightful and provocative. Unlike forum authorities, real powersports professionals...

1. Don't install head gaskets without sealing them

2. Don't regard 140 psi compression as good enough

3. Don't replace all the jets in a carburetor when rebuilding it

4. Don't fail to remove all the jets when rebuilding a carburetor

5. Don' believe carburetor rejetting is either needful or beneficial in nearly as many instances as forum "sages" do, and certainly not in connection with ethanol

6. Know that in most cases jet kits do more harm than good and that they exist as coverups for more fundamental problems

7. Realize ethanol does not harm rubber carb parts, cause corrosion, or cause leanness

8. Don't believe individual air filters change engine performance by altering CV carburetor slide movement

9. Don't insist a computer is better than a wiring harness

10. Don't advocate aftermarket air and oil filters

11. Don't measure piston clearance with a feeler gauge

12. Don't believe aftermarket big bore pistons demand more fuel

13. Are very aware of Honda valve recession

14. Don't lap valves, especially as a replacement for a valve job

15. Don't prefer LED replacement bulbs

16. Don't use dime store (bargain table) screwdrivers

17. Know that Honda valves from the 60s through the early 80s cannot be refaced

18. Are aware that Honda's replacement valve guides are oversize

19. Don't value a bike's sound over almost anything else about it, and especially more than maintenance and durabilty

20. Don't gravitate toward the kickstart ethos

21. Don't regard exhaust modifications as more impactive than intake ones

22. Don't regard user forums as the ultimate clearing houses of maintenance advice

23. Know that far too many popular modifications are in reality band-aid fixes for maintenance shortcomings

24. Know that while carb sync is a frequent way to solve a hanging idle, it is far from the only way and not even the most effective way.

25. Disdain the extemporaneous unqualified advice that characterizes online venues

26. Don't overuse plastic cable ties

27. Don't slavishly endorse resistance tests as part of electrical troubleshooting

28. Don't denigrade everything factory

29. Don't go out of their minds when they discover a 50-year old factory bulletin

30. Never hone in-service cylinders

31. Don't regard racers and engineers as more credible than career mechanics

32. Don't advocate aggressive cylinder finishes

33. Don't promote Marvel Mystery Oil

34. Are aware that aftermarket "Hy-Vo" type cam chains are inferior to their Honda originals

35. Don't believe Honda had a viable paint coding system

36. Don't use Phillips screwdrivers on Taiwan-spec flat blade screws

37. Don't use #2 Phillips screwdrivers on #3 Phillips case screws

38. Are not caught up in the JIS screwdriver nonsense

39. Know that larger than specified valve clearances improve engine performance

40. Don't regard Honda's idle drop procedure as a valid tuning tactic

41. Don't believe in the "master carburetor" theory of multi-carb synchronization

42. Don't regard carb synch as a once or twice in a lifetime adjustment

43. Don't ignorantly assume a Honda bulletin nececessarily applies to every example of the subject model

44. Know that aftermarket replacement steering-mounted vintage model Honda keyswitches are junk

45. Don't believe valve adjustment an infrequent need

46. Well understand the role of ignition service in engine performance

47. Don't regard a carburetor that takes more than a half hour to rebuild as being "difficult"

48. Know that aftermarket electronic ignitions are not superior to Honda Kettering ignitions

49. Don't claim that Sta-Bil will hurt the fuel system

50. Don't ignore or downplay the three most fundamental vintage Honda maintenance needs: silicone brake fluid, Sta-Bil fuel preservative, and wiring harness and canon plug repair or replacement

51. Understand that the aftermarket replacement parts industry is largely adversarial, deceptive and destructive

52. Don't foolishly accept aftermarket sales assurances that their products are "from the same vendor as OEM"

53. Know how to properly adjust their clutches and lube and adjust their drive chains

54. Don't slavishly, unthinkingly promote Viton o-rings

55. Don't insist that carburetor felt seals affect engine performance

56. Don't foolishly blame low cylinder compression on the compression tester

57. Don't prefer cylinder compression uniformity over average compression

58. Don't over-use thread locker and anti-seize

59. Don't like worm-drive hose clamps

60. Don't espouse modification as more important than, or even as a kind of, repair

61. Never attempt to detect vacuum leaks by spraying aerosol

62. Don't ignore the industry's most powerful troubleshooting tools such as the exhaust gas analyzer (EGA) and the more/less air test

63. Don't disdain silicone brake fluid

64. Don't regard valve-to-piston and deck height and cam profiling as unimportant and unknowable "black arts"

65. Know that the CB500/550's cam chain requires help during tensioning via the screwdriver slot

66. Don't advocate indiscriminate use of gauze type air filters

67. Don't adjust the CB350/400 four's cam chain with the engine running

68. Don't promote carburetor jetting kits over proper maintenance

69. Don't put sealer on cylinder base gaskets

70. Own thread pitch gauges, as well as other more sophisticated measuring tools

71. Don't fail to understand the need to oxidation-treat the gasoline in their carburetors

72. Understand about JASO MA, recognizing it as the single most important aspect of motor oil relative to powersports

73. Don't overuse their rear brake

74. Don't regard many models of 70s and 80s Hondas' as-designed not charging at idle as a defect

75. Use real-world dynamic charging, ignition and starting system diagnostics, not the simplistic, inconclusive static methods promoted in media

76. Are very aware that Honda's official manuals have never provided any systematic charging or ignition system diagnostic methodology

77. Know that Honda to varying degrees stopped providing effective repair information in their manuals sometime in the late 1960s

78. Know how to stop brake squeal

79. Don't disdain soldering as the correct wiring repair method

80. Disdain Scotchloks and other wire crimps

81. Are up-to-date on proper steering bearing adjustment method

82. Know about best practices for finding oil leaks

83. Know that most forum "experts" wouldn't pass an entrance exam to a mechanics school

84. Would never install a relay instead of repairing or replacing the wiring harness

85. Don't favor fitting supposedly superior aftermarket tapered steering bearings over properly maintaining the original ones

86. Don't insist that aftermarket valve guide seals are best

87. Are not confused about so-called "matched" or wearing-together engine and carburetor parts

88. Don't endorse premium fuel in 70s Honda road bikes

89. Aren't silent about such things as hazard flashers, center stands, and onboard ammeters

90. Don't advocate using Pine-Sol for carburetor cleaning

91. Believe in adequate and frequent tire pressure maintenance

92. Don't treat 70s Honda bikes as if they're throwaway "beater" just-transportation cars

93. Don't use or promote aftermarket oil filters and control cables and electrical parts and engine seals and gaskets

94. Are aware Honda used soft valves for more than twenty years

95. Don't believe a hone can take the place of a cylinder boring machine

96. Don't promote honing Honda brake cylinders

97. Don't endorse using brake cylinder hones on engine cylinders

98. Understand the technicalities of piston and cylinder wear

99. Are not ignorant about oil consumption

100. Are not "YouTube experts"

101. Don't regard abrasive blasting as a carburetor cleaning method

102. Avoid abrasive blasting engine parts

103. Don't believe ultrasonic cleaners clean parts by vibration

104. Don't believe aftermarket valve springs are necessarily better than OEM

105. Don't prefer aftermarket valve guides over the original

106. Have always known about the evils of carb rebuild kits

107. Shake their heads at forums' complete ignorance of the benefits of factory special tools

108. Don't regularly change their views on things when reality sinks in and then act like they always knew the truth (many of the items listed here have been and will continue to filter into forum posts, with the posters acting like they knew them all along)

109. Have always known about grinding brake discs instead of turning them

110. Are not adamant about 120 degree spacing of piston ring end-gaps

111. Don't insist racing carburetors work better than the stock ones

112. Don't reuse drain plug washers until they curl up like potato chips

113. Don't advocate "soaking" clutch plates

114. Don't slavishly embrace aftermarket exhausts

115. Don't promote retention of a Honda's air intake oil separation device

116. Don't believe an aftermarket exhaust necessarily increases engine power

117. Don't glue in oil seals

118. Don't regard aftermarket ignitions as superior to OEM

119. Are very aware that o-rings require grease

120. Are aware of where o-rings got their name

121. Aren't ignorant about the relationship between fuel hose and hose clamps

122. Don't "dis" factory Honda fuel hose clips

123. Aren't unaware of proper canon plug maintenance

124. Don't kick-start their machine while it is leaning on the sidestand

125. Don't think engine parts must be milled in order to make gaskets not leak

126. Know that cheap replacement valves are a poor choice for shim type engines because they don't permit a proper valve job to be done

127. Don't confuse preignition with detonation, Kettering with CDI, and magneto with energy transfer

128. Avoid recamming drum brake operating arms

129. Don't advocate the use of hammer-type impact drivers

130. Don't value chrome, powdercoat, polish and paint over mechanical rightness

131. Don't endorse using colorized wiring schematics

132. Don't remove valve springs with a hammer and socket

133. Don't advocate abrasive-cleaning spark plugs

134. Don't check spark with the plugs out of the engine

135. Regard adjustable wrenches and Vise-Grips as among the most unwisely-used tools

136. Don't whine about Honda bulletins not being published for consumers

137. Don't believe running an engine out of fuel will prevent carburetor varnishing

138. Don't recommend simple carb draining as a means of preventing varnishing

139. Know of the principle of unintended consequences and how it applies to most "upgrades"

140. Are very aware of Honda's long-published error of 12 foot-pounds torque for a 6mm bolt

141. Don't unwittingly advance Honda's gasoline octane number error in its vintage manuals

142. Know better than to use silicone sealer anywhere on an engine

143. Don't use abrasive means of removing old gaskets

144. Don't simply mill down a cylinder assembly's protruding cylinder sleeves

145. Know that installing 2.2 ohn ignition coils on a 70s SOHC Honda four will not result in electrical issues

146. Don't believe that 70s SOHC Honda four charging systems break even at 2000 (or 3,000!) rpm

147. Avoid using Neway valve seat machining tools

148. Don't believe braided steel brake hoses necessarily improve brake function (see unintended consequences above)

149. Don't prefer vintage Honda block-sipe and ribbed tires over modern high performing tires

150. Don't pry engine parts apart using screwdrivers

151. Don't hammer on engine cases to separate them

152. Don't regard the 60s-70s CB450 twin's all-steel clutch pushrod as equal to the later bimetal version found in the final year 450 and the 500 and the 500 four

153. Don't tie down a trailered bike while it is still on a stand

154. Know that WD-40 will make your engine's cylinders rust faster than will engine oil

155. Are very aware that there is no such thing as piston and cylinder and valve and valve seat "break-in" or "bedding-in"

156. Avoid tapered valve guide machining pilots because they result in non-concentric valve seats

157. Know that the forum ethos of milled heads and oversize o-rings to "cure" SOHC four head gasket leaks is silly.