SOHC.co.uk Forums > CB500/550

idling problems on cb550, please help

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Chris400F:
Have you tried swapping plugs between cylinders? I haven't seen this mentioned so far, should be an easy thing to try.

tom_b:
Yeah i kind of thought it can't be the coil, so I ordered the cap, but I'll try swaping the caps between no4 and no1 later this evening, I'll also check the sparkplug.

Thanks for the info everyone, it's really useful!!

mihai.i:
I had almost the same problems with my CB550k 1978. Rebuild the carbs, timing, valve adjustment and carb sync but idle was way off..and the cyl 1 somethimes not fired.

Turn out there was a bunch of causes:
1- there was some air leak ant cyl 1 and 4
2- the timining was not ok..i discovered only with the strobe light...i removed the advance cleaned, put it back, retimming with the strobe..is ok now
3- i changed all the sparks plug and spark plug sockets (NGK)
4-I got low compression 7-7-8-8..its a bit hard to start in cold season but during summer in ok

The main reason for not idling was the air leak, and the main reason for not firing cyl 1 was bad timing!

Ashdowner:
Mihai, how did you find the air leaks and where exactly were they?

tom_b:
So...I still can't get it to idle good.. previously i said that cylinder 1 was not firing properly, and 2 of the carbs were leaking over night so I've changed the ignition coils which seemed to help and it seems to be firing better now but still less hot than the right side, and also the carbs don't leak no more, assuming that the cylinder is burning off the petrol now? I've checked the velvet clearances and adjusted them (also should there be oil under the tappet screws? where the rocker arms are?) I've checked the timing using a timing light with alligator clips and noticed that the light lights up before the F 1.4 mark reaches the index mark, but very close to it, checked the breaker point gaps and they are between 0.3 to 0.4 mm, which is by the manual book.
I can't really check for air leaks because it does not idle same all the time..
once i close the choke there is a lot of white smoke, but i need to keep playing with the choke because it dies on me otherwise,
but started it a bit later and it wasn't smoking white smoke anymore, just a little black when revving it, and it revs really hard, as if there is no power and is choking....
anyway would a video help if I would film it??

Thanks

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