Author Topic: 1978 CB 750K running very rough..  (Read 477 times)

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Offline crousos

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1978 CB 750K running very rough..
« on: September 29, 2020, 04:29:16 AM »
my 1978 CB 750K running very rough.. lately with a lot of backfiring .. it started about a month ago  first it looked like on of the spark plugs was burned up .. but I replace all the plugs and it seemed to be running ak for a short time but now its back to the same.. it backfires all the time and is running like crap...  it seems to be better at 4.. 5 thousand RPM but not great...

Also checked the points ant it look ok...
the same for the carbs...

I had this bike for over 10 years and this is the worst it had been ...

any ideas greatly appreciated

Constantinos

Offline goodtryer

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Re: 1978 CB 750K running very rough..
« Reply #1 on: September 29, 2020, 05:51:38 AM »
Check the spark plug caps. I had one recently that was way over 5k ohms. Bike idled much better once I replaced the cap.

Also check that you don't have excessive sparking at the points. Could be a bad condenser. Had that cause poor idling on another bike.

Cheers
"Tolerance will reach such a level that intelligent people will be banned from thinking so as not to offend the imbeciles."
-Dostoievski

1977 CB550K
1978 CB750K
1973 CB500K