Topic: 77 CB550...Stalling/Residue

[BMiller]

Two steps forward, one step back.  I've revived the bike from 2 years sitting so that it starts and runs out OK by cleaning (but not rebuilding) the carbs.  (I have since ordered the carb gasket kit from Honda.)  I kinked a throttle cable in one of my early carb removals, so have new cables coming.  I have replaced points, plugs, condensers and done the simpler static timing.

Continuing symptoms are stalling (won't idle) and a new phenom...rusty residue dripping from the nipple at the exhaust low point.  Plans are to install new throttle cables and see if I can adjust to keep running, then rebuild carbs with gasket kit if it's still not running well. 

Any other ideas/suggestions are appreciated.

[csendker]

Did you drain the carbs 2 years ago?  I bet they're gummed up inside, which should hopefully be resolved with your rebuild.  If you don't replace the jets, make sure all of the tiny holes are cleaned out.

[petersan]

I'm not sure about the rusty residue - but my '76 550 had a difficult time idling when I first got it.  Rebuilding carbs with new jets, etc - will probably help.  When putting it back together make sure air idle screws are all turned out the same - follow a manual for turning out air screws and adjusting idle.

If that doesn't fix it (didn't for me) - I'd suggest sync-ing or balancing the carbs.

[byidesign]

Hi, the rusty water/residue from the exhaust is probably the condensation,
    from it not being thoroughly warmed up.
      my 650 will drip for @3-5 min until i get going down the road, and
       warmed up. be sure even after cleaning the carbs, that you didn't
    introduce more crap when you hooked it all back together,water,
       {inside of fuel lines , tank petcock,etc.]
          drop a carb bowl and see .
              doesn't take much to clog idle jets.
                 hope it helps
                          Bruce

[Dennis]

Continuing symptoms are stalling (won't idle) and a new phenom...rusty residue dripping from the nipple at the exhaust low point.  Plans are to install new throttle cables and see if I can adjust to keep running, ......

Any other ideas/suggestions are appreciated.

The new cables should not effect idleing or your stalling problem. Any work that you do on the carbs in this area you can do without the new cables. Remember that cables are supposed to be installed with a little free play. See manual for adjustment procedure for your model.

As far as the rusty drip just what Bruce said, condensation. The rusty color is telling you something about the interior condition of your pipes.

[TwoTired]

Cleaning carbs is only effective if more crud from the gas tank doesn't reintroduce blockage material.

Drain, catch, and examine the carb bowl contents, bits larger that .014 inch can block the slow jet and the engine won't idle.  If these are still flowing and you have even bigger flakes in there, the tube that feeds the jet can plug while the engine sucks on the jet.  When the engine dies, the suction stops and the flake falls to the bottom of the carb bowl.  The engine restarts and runs for awhile until the flake gets stired up again and finds the jet tube, another stall.

Your carbs have press in slow jets that can be difficult to clean.  Also, there is an o ring behind the idle mixture screw that doesn't take kindly to some carbs cleaners, like the agressive ones that work the really well.  When you rebuild know that these jets can be removed cleaned and tapped back into place to ensure these and the passageways behind are clear.

Anyway, don't forget to check for tank rust and the tank filter above the petcock, too.  If that filter is buggered, replace or put in an inline.

Cheers,

[BMiller]

Thanks.  I've had the carbs off 3 times and last time looks like main & idle jets stayed clear.  There are no flakes or particles when I check the bowls.  The bike runs OK at higher RPM, but stalls particularly after it has warmed up.  I'm thinking I've damaged some gaskets or o-rings in my cleaning or I've just idle/throttle/air adjustments all out of whack.

I'll be installing gaskets/o-rings upon arrrival.

[petersan]

Then I'd make sure all air screws are turned out the same amount - there are nice instructions on the proceedure in the carb FAQ (I think?).

Again, if that doesn't help - try to get them synched.

[TwoTired]

If you've had them on and off that many times, I would also check the rubber manifold couplers for air leaks at the intake runners.

Also, changes to air filtration and exhaust from the stock components will likely require changes to idle jet selection and needle settings, possibly main jet, as well.

Have you ever balanced or synced the carbs?

[BMiller]

I adjusted (took slack out of) the throttle cables and made sure all idle mixture screws were set the same.  Running good, not stalling, but feels like I'm not quite there.  I bought carb gasket kits from Honda. 

My Clymer book is too generic (not my carbs)...I'm not sure where the 5 o-rings go.
Approx. OD:
8mm (2)
7mm
6mm
5mm
Any insight as to where they go is appreciated.

Thanks for all the info to date!