1977 Honda CB750 update 4- valve guide wear video

Since I could never get the bike to run well even after all the normal tuning and carb cleaning, I decided to pull the motor apart and take a look. It had a very “rattly” sound to it which bothered me. Nothing looked wrong except the valves had a lot of wet carbon build-up in them which suggested valve stem seals. But when I took the seals off, they were still pliable and soft. I checked a couple of the valves in the guides and they seemed fine… BUT I must have checked a couple of the intake valves because as you will see in this video clip, the exhaust valve guides are totally shot. This is a common problem with the SOHC 750’s- they wear out the exhaust valve guides and especially cylinders 2 and 3 which run hotter that 1 and 4. If you have an old CB750 and the guides have never been updated with newer bronze or cast iron guides, they are probably in bad shape like these. You can get APE bronze or Kibblewhite cast iron guides and probably only need to do the exhaust side.

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