CB550 F 1976

[Johnny4428]

Hi Matt and welcome to the forum. I would want some reassurance that all air and fuel passages have been cleaned properly, usually the culprit if you are getting combustion on all four cylinders and won’t idle. Also proper vacuum sync. Have you tried adjusting air screws?

[McCabe-Thiele (Ted)]

Hi all, new to the forum and having been enjoying my CB550 F for a couple of years right up to this summer when I started having problems.

It lacks power under weight like it’s missing and won’t tick over. What had replaced so far:

New battery, coil pack spark plugs, converted to electronic ignition (old crank was bent) getting 13amps back to the battery over 2000 revs. Checked and adjusted the valves. Carbs cleaned new jets and set up.

I’m at loss now as what could be wrong, has suggested replacing the alternator?

Thanks

In the start of this thread you say your 550 has been running okay for a couple of years, then this summer problems started. Are you doing all the work yourself or have you used a motorcycle repair shop. I ask as I can't see how the distributor cam came to be bent if it's run ok for two years.

Regarding your alternator voltage output it can be adjusted via the regulator. I would check and clean the contacts on the charging circuit before tinkering with the regulator.

What make coils did you fit, are they the correct impedance?
What plugs did you fit, resistor or not?
Check you don't have resistor caps & plugs.
Is there a healthy blue spark?

If the spark side including timing is all good, then I would be checking the fueling side.

[Oddjob]

Plus some electronic ignition systems require timing at full advance. If you don’t know that and set it on the F mark at tickover it won’t idle anyway.

Hence Bryans insistence on knowing which brand it is.

[McCabe-Thiele (Ted)]

With online diagnosis, the Devil is in the detail.🤔

[Sesman]

I recommend you reverse engineer in order to progressively and logically eliminate the problem. Revert to standard equipment and progressively ‘improve’ the bike? I’d leave the replacement carb brassware till last.