Topic: CB 550 Crazy rev problem?

[mshcb550]

Hey Guys!
1978 CB 550 and it's revin like crazy!
Starts easy enough-was a daily driver before this crap- with the kick but it's at 3,500 rpm or stalls below that.  When I give her a little throttle she jumps up to 6,000 and stays or starts climbing fast up to red line.  Throttling more and trying to throttle down doesn't work, I have to shut off with the key-then shes reset back to the 3,500 and does this each time I try.  ITS LIKE A GOST IS REVING HER!?!?!The bike was ok one day then started this crap.  I pulled all the carbs-fun- and pulled the floats bowls off.  All looks clean, cleaned the jets, floats move freely all looks good.  So I thought it might be cables, new cables and grip tube- now the problem off reeving like crazy just happens more efficiently!  The main idle adjust doesn't effect it, throttle moves freely open shut no hang ups,  external springs look OK.

My Girl is gettin sick of driving me to work, whats up with my bike?  Any ideas?[/font]

[OldSchool_IsCool]

First, Welcome to the insanity!

My first thought is that your throttle return spring is missing or has fallen off.  When you move your throttle grip, watch the throttle bar on top of your carbs.  Does the bar move in accordance with the grip?  Both "push" and "pull"?  What happens if you operate the throttle bar by hand without the grip/cables?  Pull the slider cover off the top of a carb or two.  Does the slider move up and down with grip movement?

[mshcb550]

Yes the return spring is in good shape, nice n strong, I need to use the grip to open the Carbs.  I have looked in the top of all four of them, all is working in unison.  The Carbs all snap shut when I let go of the Grip.  Everything external looks good.  Could this be a float problem?  I did just take them apart and all the floats were moving freely but who knows, if nothing out side is moving what else would cause the reeving?

[OldSchool_IsCool]

Did you make any changes to your idle air screws?

[clarkjh]

Air leak somewhere?

James

[TwoTired]

There is a fast idle cam coupled to the choke.  It has a speed adjustment that blocks closure of the slides.  Check it's operation and adjustment.

Air leakage at the carb couplers.  Look for cracks, spray joints with WD-40.  If idle changes, block leakage.

If it stalls when the slides are truly closed down, look for blocked slow jets.

Do the symptoms remain with the fuel petcock on reserve?  What is your fuel state?  The slow jets starve first with low fuel.

The 78 PD carbs do not have air screws.  They have Idle mixture screws, which he indicated he didn't change to induce the problem.