Topic: '71 cb550 with idling problems

[vulture0027@gmail.com]

My '71 cb550 starts up, but fails to stay running. If I keep pressure on the throttle it continues to run, but as soon as i lay off the gas it just dies. i've sat there for 10 minutes with my hand on the throttle and it'll run, but as soon as i take my hand off the gas  it dies. does anyone know how i can fix this?.....PLEASE?!??!

[Old Moe Toe]

There is usually a screw (a pretty big noticeable one) on the bank of carburettors that, when you turn it one way increases the idle revs. Of course there could be lots of other things it could be but that is a good place to start.

[calj737]

Your ‘71 is a 500, not a 550, unless it’s actually newer than a ‘74...

Does it die because the idle seems low, or because it appears to be running out of gas? Do you have any history with the bike, or any information you can provide? Is the choke stuck on? Is there fuel flowing from the tank? Is there an inline fuel filter improperly installed that’s interrupting fuel? Are the float heights set wrong? Are the plugs so badly fouls, they won’t fire? Did someone replace the idle jets and muck up the settings? Have the carbs been cleaned recently? And so on, and so on...

A little hint for you, these are air-cooled motors and as such don’t like to sit in the garage and idle for 10 minutes. They will overheat. They need air flow across the motor fins to prevent this

[flybox1]

Get a shop manual or clymer for your bike and start on the periodic maintenance items.
This 'fixes' the majority of bike issues if done correctly.