Posted by Rob Kleinschmidt on October 15, 2007, 11:57 pm
> >> Whoohoooo!! I finally got that bike working. Finally ressurected my
> >> CB550K. Fuel flow problems up the yang, cleaned tank, removed old
> >> filter,
> >> replaced replacement filter, starts on first try.
> >> Ahhh, now I can break her in and start riding. except one teensy
> >> problem.... She idles at 9,000 RPM.
> >> The service manual doesn't say much on where to start with this one, so
> >> I'm
> >> wondering if someone can kick me in the right direction. I'm thinking
> >> Idle
> >> control stop, but it doesn't really say whether the screw should be in
> >> all
> >> the way or all the way out. But I'm expecting there's more to it than
> >> that.
> >> My theory is that my uncle, the previous owner, didn't realize the gas
> >> lines
> >> were plugged and so tuned it to compensate for the poor to nonexistent
> >> fuel
> >> flow.
> > Start by checking your throttle cable(s).
> > Most likely problem is a damaged cable that's not
> > allowing a carb to return to idle.
> > Look at the carbs and make sure that the arm stops
> > are sitting flush against the idle control screws before
> > you do anything else.
> > Backing off these screws should allow the butterflies to
> > close further and reduce the idle speed but if it's idling
> > at 9000 RPM, I don't think it's a badly adjusted screw.
> > Sounds more like a missing spring or screwed up cable.
> The mechanisms work, I verified that just now. The arm is moving with
> throttle twists, the stop is set so that it just barely touches the arm on
> the throttle assembly. I notice that the throttle cables were loose and
> there is a bit of slack in the throttle and the action of the throttle is
> weak and sluggish - but I don't know what is typical in a bike like this.
> It certainly doesn't snap back like I would expect it to. I fear adjusting
> the throttle cable, I'll probably screw it up like I did my clutch cable,
> but at least with a clutch cable you can start from scratch - with a carb
> you don't know what part of the voodoo spell you messed up on.
I don't know what "action of the throttle is weak and sluggish"
means. If there's a lot of slack, then possibly the idle screws
were in fact opened too far.
"stop is set so that it just barely touches the arm on the throttle
assembly" also leaves me a little mystified. When you release the
throttle, the stop on the butterfly mechanism should be making
contact with the idle adjust screw.
You could try backing off the idle adjust screw(s) to see if
the rpm drops. Count how many turns you make so you can
keep track of your adjustments. As suggested already,
take a look at the choke too. It's also possible that there
are problems elsewhere in the carb or in the ignition timing.
Sounds more like a simple mechanical problem than anything
else. Had you already fiddled with the idle screws or cables
before you first observed this problem ?
Posted by Fake Name on October 15, 2007, 9:05 pm
Congrats! you're in the home stretch now.
Look at the throttle cable and watch how it moves. You will then see
how the screw will adjust the stop position. Wind it in so the
throttle closes. Also check for correct and free movement from the
choke cable.
Posted by Eigenvector on October 15, 2007, 8:23 pm
> Congrats! you're in the home stretch now.
> Look at the throttle cable and watch how it moves. You will then see
> how the screw will adjust the stop position. Wind it in so the
> throttle closes. Also check for correct and free movement from the
> choke cable.
Choke cable, didn't think of that, I do have to goose it to start with the
choke on, something you shouldn't have to do.
So I'm looking at two things - throttle cable and choke cable.
Posted by The Older Gentleman on October 16, 2007, 2:27 am
> Whoohoooo!! I finally got that bike working. Finally ressurected my
> CB550K.
Nice. And this weekend, I collect my CB550F restoration project......
--
BMW K1100LT 750SS CB400F CD250 CB125 SL125
GAGARPHOF#30 GHPOTHUF#1 BOTAFOT#60 ANORAK#06 YTC#3
BOF#30 WUSS#5 The bells, the bells.....
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> >> CB550K. Fuel flow problems up the yang, cleaned tank, removed old
> >> filter,
> >> replaced replacement filter, starts on first try.
> >> Ahhh, now I can break her in and start riding. except one teensy
> >> problem.... She idles at 9,000 RPM.
> >> The service manual doesn't say much on where to start with this one, so
> >> I'm
> >> wondering if someone can kick me in the right direction. I'm thinking
> >> Idle
> >> control stop, but it doesn't really say whether the screw should be in
> >> all
> >> the way or all the way out. But I'm expecting there's more to it than
> >> that.
> >> My theory is that my uncle, the previous owner, didn't realize the gas
> >> lines
> >> were plugged and so tuned it to compensate for the poor to nonexistent
> >> fuel
> >> flow.
> > Start by checking your throttle cable(s).
> > Most likely problem is a damaged cable that's not
> > allowing a carb to return to idle.
> > Look at the carbs and make sure that the arm stops
> > are sitting flush against the idle control screws before
> > you do anything else.
> > Backing off these screws should allow the butterflies to
> > close further and reduce the idle speed but if it's idling
> > at 9000 RPM, I don't think it's a badly adjusted screw.
> > Sounds more like a missing spring or screwed up cable.
> The mechanisms work, I verified that just now. The arm is moving with
> throttle twists, the stop is set so that it just barely touches the arm on
> the throttle assembly. I notice that the throttle cables were loose and
> there is a bit of slack in the throttle and the action of the throttle is
> weak and sluggish - but I don't know what is typical in a bike like this.
> It certainly doesn't snap back like I would expect it to. I fear adjusting
> the throttle cable, I'll probably screw it up like I did my clutch cable,
> but at least with a clutch cable you can start from scratch - with a carb
> you don't know what part of the voodoo spell you messed up on.