Topic: Help Me My CB 550 dies at every light!

[IllCB550]

I have a1974 cb550 She starts ok but idles at around 2700-3000 rpms, and this morning when I was leaving for work she started acting all funny.   she started galloping( giving poor throttle response) then she died( no matter how nuch throttle was given) she was very difficult to restart I had to turn the choke on and offto get her to start and when she did she would again ide ok(abet at high rpms) but then the same problems happened and she would die. Does anyone have any guesses as to what this might be.   I am no mechanic but am determined to learn all I can about this bike (I would love any suggestions on what tools I should get, a basic tool set to have for this bike would be great.)

[Badger 5]

That seems like a very high idle.

[kslrr]

How long have you had this bike and any idea of when the carbs were last checked, cleaned and synchronized?  How about the air filter and fuel system?  And the ignition timing and valve clearences should be checked as well.

A basic tool set:
Metric open end and closed end wrenches
Metric socket set
Phillips head screw drivers
12v light with alligator clips for static timing check
4 gauge carb synchro setup
Valve tapit clearance gauge and adjustment tool
Simple volt/amp/resistance meter (also known as a multi-meter)

Thats all that comes to mind right now.  Good luck.

[pyro139]

check your plug's i had similar problem on my non honda bike recently, first it died on me half way up a mountain, had push it 5km up a mountain thank god only a 230pound bike if was my honda would have been no way, then when got to top shed start up at high idle throttle would have zero effect after disasewmbling bike spending hour examining cables choke carb and every thing else decided inspect plug the tip had melted and warped, couldnt find  any place open with plug in area, was day of one of the hugest motorcycle rallys in ontario(friday 13th port dover) i made it half way to rally had grab pliers bend a new gap on plug and ride home in shame backfiring and miss fireing worst than a harley.

[IllCB550]

I have had the bike since 06 but since then I have only ridden it 100 miles( had a blow out within two weeks of ownership, took me almost a year to get the fixed) I have never checked the carbs or had them cleaned, the air filter needs replacing as it is very dirty, can all this be done with the tool set up you suggested?

[OldSchool_IsCool]

The gallop makes me think it's running rich.  Pull your spark plugs, noting which cylinder they came from (they are numbered 1 thru 4 from left to right as you sit on the bike).  If the plugs are wet or black & sooty, then yes, you are running rich. 

When you adjust the idle screw (thumb screw under the right side of your tank), does it just plain die under 2700?

As for tools, a thin-walled plug wrench will be needed to get at plugs #2 & #3.  Sears or any M/C shop should have them.  You want the 12mm size.  Don't be fooled by the fact the hex size of your plugs is actually 18mm.  Plug wrenches are sold by the plug's tread size, not it's hex size.  don't ask me why.

[pyro139]

How long have you had this bike and any idea of when the carbs were last checked, cleaned and synchronized?  How about the air filter and fuel system?  And the ignition timing and valve clearences should be checked as well.

A basic tool set:
Metric open end and closed end wrenches
Metric socket set
Phillips head screw drivers
12v light with alligator clips for static timing check
4 gauge carb synchro setup
Valve tapit clearance gauge and adjustment tool
Simple volt/amp/resistance meter (also known as a multi-meter)

Thats all that comes to mind right now.  Good luck.

you missed one tool a long reach spark plug wrench

[pyro139]

reminds me also need a plug gap tool for measuring the gap

[TwoTired]

I have a1974 cb550 She starts ok but idles at around 2700-3000 rpms,

This is not idle.  Idle would be 1000 RPM.  This is running on the throttle valves in the slides instead of the slow jets.  Which, in your case are likely plugged up with debris.  The lack of throttle response also supports the plugged slow jet diagnosis.

However, this is only the most major problem.  A dirty air filter tells me you haven't performed a tuneup, which these bikes are supposed to get every 3000 miles or 3 Mos.  Dirty air filter can also make the spark plugs carbon foul and stop sparking.  Check your head pipes for even heat cylinder to cylinder.  I use the "flash touch" method.

The tool kit that comes with the bike has almost all the tools needed to get your bike going again.  A timing light can be made from a 12 v  bulb and jumper wires with alligator clips.  Just add a set of feeler gauges, and you should be on your way.

It is possible to remove and clean your slow jets while the carbs are still on the bike.  You will need a correct length #2 cross point screwdriver to reach the bowl screws, and a pliers to remove the hose clamps.  A flat blade screwdriver for the bowl drain screws and slow jet removal, and, some spray carb cleaner.

You can download a Shop Manual from this site (somewhere).

The fuel petcock has sediment bowl.  Unscrew that an examine the contents.  The slow jets are the smallest orifice in each carb, about 0.016 diameter.  Anything in the fuel larger than this size can block the slow jets.

Cheers,

[IllCB550]

I get those tools and this weekend and do the suggested check, is there any other info I should get I am trying to download and print out the service manuel I found online I hope that it helps. thanks again for all your input.

[OldSchool_IsCool]

Here is a link to a thread started by another new member when he was looking to buy a 550.  The 2nd post in the thread is a list I've been working on to give new 550 mechanics/riders a few things to keep in mind.  I know you have owned your bike for a while, but I get the impression you haven't done much with it.  Sorry if some of the comments seem a little elementary, they are really just there for completeness.

By the way, welcome to the forum!!

http://www.sohc4.us/forums/index.php?topic=21190.0

[gold01ca]

a decent impact driver for those nasty, siezed, phillips head bolts.
a must have in your tool box, cheap and effective.

cheers!