Topic: performance mystery

[danarchy77550f]

Good Afternoon everybody,

I have a 1977 CB550F that i have been working on for about a year and a half.  The past three months i have really been digging into the electrical system.  I discarded the points and replaced them with electronic ignition, relaced my started solenoid and flasher relays etc, and even relaced my cheap battery with an upgraded gel one.  The bike is running better and more reliably than it ever has been. 

A couple weeks ago after i had it on a tender after i replaced the battery on startup it felt truly amazing.  The throttle responded crisp and clean and it accelerated easily twice as fast.  i quickly went out to the main street and punched it.  It was faster than ever and it was a true thrill on my little bike.  but less than a minute later it returned to its "normal" self.  It is usually a little boggy coming out of first , but at the time it was not the case.  it has happened randomly since but i cant figure out how to keep it that way?

has anybody ever had this happen? i would love to get it running like this all the time.

[flybox1]

glad you dug through the electrical, but you mention nothing of the other maintenance/tune-up items, and if you completed them.  not to mention intake and exhaust mods if you're no longer stock..
holding out? what gives? 

[dave500]

how old are the plugs caps?has it new plugs aswell?

[Nick0]

I had something similar happen to me awhile back, turns out it was the chokes vibrating shut. I found that I would put the choke on to start the bike and once it was warmed up I would open the chokes but after a short bit of riding I would begin to notice the performance loss that you are noticing, I thought I was electrical at first but it turns out I had failed to replace my choke lever detent ball and spring when i rebuilt my carbs and as a result my chokes would vibrate shut after a brief ride.  (It's  little ball and spring that locks the choke lever up and holds the chokes open). Not saying this is necessarily what your problem is just something to check for.

[danarchy77550f]

im running pod filters with a cherry bomb ( glass pack ) exhaust.  the plug caps are ngk ones that replaced the old stock ones.  it has fresh plugs.  the choke has never really been a problem but it could be worth looking at.  I havent dug into the carbs as of yet besides pulling off the float bowls to peek.  they were unreasonably clean! im sure my pilot and main jets need to be upped due to the mods but they have been on there the whole time and this just started happening recently.