CB650SC/New Owner Suggestions

Should replace

O-rings

Avoid fuel leakage:

• Carb "Fuel-Tee" x2
• Carb bowl seal x4
• Carb fuel tubes & "Vent-Tees" x8(x2+x2+x2+2)

Avoid Air leakage(leads to lean):

• Carb-to-insulator-to-head x8(x2+x2+x2+2)

Avoid low head/cam/tappet lubrication/valve tick:

• Valve-train oil pipe x10(x2+x8)

Avoid low oil pressure/dirty oil contamination?:

• Oil filter tube x3?
• Oil filter cover x1 (sometimes comes with new filter, can be reused carefully)

Must clean/rebuild

Carburetors

• Check and replace with same jets & emulsion tube or clean, check, and reuse (order individually by size, no kits)
• Reuse main-jet needle (do not trust "kits")
• If a po crushed the mixture screw seats, tuning will go from 2-3 turns out to something like 1/4-3/4 of a turn out
  • The hole that the very tip of the mixture screw "needle" goes into should have a narrow, raised "lip" surrounding it. If you look down the mixture screw hole, and see a "pin-hole" that is flush to the base or has "starred" out metal around it that looks like a pressed rivet, the mixture seat is crushed and destroyed.
• It goes without saying, vacuum-balance the carbs
  • Nothing beats digital gauges for speed, ease of use, or accuracy.
• If you don't have and can't get "EPA"/back-out lock caps for the mixture screws, they -will- back out and lead to fouled plugs
  • 3D printed replacements do exist and can be thread locked on just like the originals
  • In desperate situations a spot of white, high-temperature, fuel-safe thread sealer can be used to secure the screw AFTER reading the spark plugs to confirm the tune
    • Blue thread locker will loosen from engine heat even if the carbs are cold
    • Red thread locker will be a huge mistake

Hydraulic Tappets

• Follow manual for removal
• Use allen key (my recommendation), smooth bore side of 1/16 drill bit (Clymer manual), or special tool Honda 07973-ME9-0000 to bleed out oil
• again bleed upright under kerosene (mineral spirits or maybe even diesel fuel in a pinch?) to clean
• bleed out the solvent from the last step
• bleed under engine oil until primed (pressing on the tappet without the "bleeder pin" inserted should feel like it is basically completely solid
• Keep upright and install with the tappet lower hole toward the centre (toward spark-plugs) squirter hole