Topic: '77 CB550f - Whirling Sound

[scrappyike]

I have a CB 550f I have just had carbs cleaned and rejetted for new MAC exhaust.  Now I have an issue with a whirling sound coming from engine when I get to top of the gear.  At that point, the power falls back and when I shift up, it is fine until you get to the upper part of that gear, shift up and fine until upper part again.  I cannot get bike above 70mph.

It's a new acquisition and have not ridden it before because of the carb issue. 

Any ideas? 

Thanks in advance,
Ike

[Bankerdanny]

I'm afraid a 'whirling sound' just isn't a description I can work with. Maybe you can make a video.

Did you clean the carbs or did somebody else?

The F came with a 4-1 exhaust stock, I wouldn't think that swapping to a MAC would require re-jetting. Are you running the stock air box and filter?

Have you confirmed that all the wiring in the ignition system is in good shape, the points are properly gapped?

Have you done the 3,000 mile tune-up? If you download the factory repair manual (there is a link included in a thread permanently attached to the top of this board) it includes the checklist.

There are so many things that could cause your issue, too rich, too lean, gap on the points too small, excess resistance in the plug boots.

You need to tell us more about your bike and what you have done to it so far?

[TwoTired]

I have a CB 550f I have just had carbs cleaned and rejetted for new MAC exhaust. 

Cool.  Carbs cleaned and changed from stock. ...to what?   "rejetted" is a lot like "repainting".  What shade of lavender- pink is that?

BD's questions are all valid.  I'd add plug deposits/condition to the list.
  But, the F model had special jetting for it's stock 4 into 1.  The MAC changeover does need carb rejetting, mostly to K model specs if the air filter is still stock.

[reddyvv]

Does the whirling coincide with a little jump in RPM? Could be your clutch slipping if that's the case.

[TwoTired]

Does the whirling coincide with a little jump in RPM? Could be your clutch slipping if that's the case.

Made me think of a tach or speedometer with dry bearings.  They make a sound due to the shafts chattering along the outside of a bearing race, rather than just spinning within.  I call that a "spooling" noise.  But, maybe whirling fits, too.