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Diagnosing engine noise/problems on a CB400NC

psgnw

Member
Joined
Oct 12, 2022
Total Posts
23
Total likes
3
Location
Trondheim, Norway
Hi! I have some rattle and ticking on my CB400NC (Superdream 1982 model). What I have done so far: Adjusted the valves, reset the balance chain (the shaft spun freely, and the dot ended up within the margins). Adjusting the cam chain changes get rid of the chain rattle so I guess it works (seems to move freely). There is still some "clinks" and knock/tick i can't get rid off. Oil is of course changed according to intervals and level is good (oil light works as it should). Starts right up and idles nicely. Some white smoke on startup on colder days, but no smoke when warm. A slight weep from the valvecover (New rubbers under the screws, but will change the gasket in winter).


Here is a video of the amount of slack on my camchain. This is with the adjuster loosened and the flywheel on "T":

https://youtube.com/shorts/Rn3nqMj9doA


Here is how the engine sounded before i adjusted valves, camchain and balancer chain:

https://youtube.com/shorts/WpRFXh18Qhc

Sound before the last valve adjustment. With the effects of engaging the clutch:
https://youtube.com/shorts/nC8Ui6Gc0x4


How the engine sounds now:
https://youtube.com/shorts/Nqo6wDDUqvc


Any insights on how to get it "smoother"?

Ps. I'm using 10W40 mineral oil.
 
The only thing left would be to inspect each of the valve adjust screw tips. They can/will fracture the tips so there's a rough end instead of smooth.
Engine actually sounds normal, well tuned sewing machine.
 
Thanks. It sounds much better than it used to for sure :) It still vibrates "a lot" around 4000-5000 RPMs. How does the cam chain look in the video? Too loose or normal?
 
Thanks for the insight LongDistanceRider! I have ordred 6 valve adjust screws, and will install them when I park the bike for winter.
 
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