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After outdoor winter storage, my cb550sc doesn’t idle well nor does it start well. At low speeds, it frequently shuts off. At high rpm’s and with choke, the motor seems to run well.

I have carefully gone through Clymers and replaced fuel with fresh fuel, replaced my spark plugs, checked the spark cables, checked ignition coils, replaced my CDI, added seafoam, and checked for fuel leaks without finding any. Replacing the CDI brought back a spark in my spark plugs and with some effort, the bike now starts. However, the spark is not the fat blue spark described in Clymers, it is a yellow thinner spark. Though this bothers me, the motor does run well at high rpms with the choke on.

My conclusion? The low speed jets are clogged and the carbs need to be cleaned. This scares the #$%@ as I have never touched the carbs before. Luckily to go with my Clymers, there are several threads that discuss this topic along with some great tips from TMW. Here is what I have gathered that I need. Please let me know if I am missing something.

1. 4 carburetor kits from eBay (# 4639667240 or #4592001816) ~$65 bucks
Do I need to get kits with the fuel filter and countersunk allen bolts, or would the kit with only O-rings and needles suffice?
2. carburetor cleaner mix
3. armor-all
4. liquid wrench
5. Hammer to gently wiggle out carbs
6. Can of compressed air

Lastly, what route should I go with? Is it just a matter of cleaning the jets and needle by soaking them in some carb solution and replacing the o-rings OR do I have to do a complete rebuild and synch?

Thanks guys.

dont waist your money on carb rebuild kits until you find you need them. I recently rebuilt the carbs on my cb360t that had been sitting for 3-4 years outside, and all they required was taking them apart, cleaning them thoroughly, letting them soak, and putting them back together and getting them adjusted properly.

9 times out of 10 you really dont need a rebuild kit, unless you find something is broken, or they are REALLY gummed up.

screw liquid wrench, get PB Blaster at your favorite parts store. Ten times better then liquid wrench.

for soaking, i used sea foam. toxic stuff, does the job well.

You're on track for the compressed air.

There are a few good writeups on the net to help you out. Id suggest taking digital pics as you go along, to help you remember what went where.

good luck!

Thanks for the amazingly quick reply...

I had a feeling rebuilding isn’t necessarily the answer... but if I elect to clean, don’t I need a new needles, float gaskets, and o-rings? Doesnt this mean i need to buy the kits?

I didn't need a kit when I rebuilt my carbs. I just cleaned everything well, soaked it, and put it back together. The Clymer's manual does an excellent job of explaining how to take apart, and put back together the carbs.

What exactly does it mean to synch the carbs? some have said it is simply an adjustment of the linkage but elsewhere I’ve read you need a mercury gauge and an auxiliary fuel tank to synch the carbs screws. What am I missing?

What is the idle-drop adjustment? Is it the same as the idle adjustment screws using a separate low speed tachometer? I can’t seem to find “idle-drop” term in my Clymers.

Where do I adjust the air mix screw… is that what Clymers calls the “pilot air screw”?

gerpena wrote:What exactly does it mean to synch the carbs? some have said it is simply an adjustment of the linkage but elsewhere I’ve read you need a mercury gauge and an auxiliary fuel tank to synch the carbs screws. What am I missing?

What is the idle-drop adjustment? Is it the same as the idle adjustment screws using a separate low speed tachometer? I can’t seem to find “idle-drop” term in my Clymers.

Where do I adjust the air mix screw… is that what Clymers calls the “pilot air screw”?

yea, synching the carbs if when you hook up a mercury gauge to each carb and adjust them until the pressure in each carb is the same. You do it after you set the idle adjustments, set the floats, all that stuff.
You really need to read up here:
http://www.dansmc.com/MC_repaircourse.htm

specifically :
http://www.dansmc.com/carbs2.htm and http://www.dansmc.com/carbs.htm

and while you're at it, read this page too:

http://oldmanhonda.com/MC/Rcarbs.html

After that you should have a good general idea of what needs to be done.

If i were you, iw ouldnt worry about synchin the carbs just yet. Just get them off, clean those suckers out, out them back together, and see how the bike runs.

here is another writeup on carb cleaning that i kee bookmarked:

http://www3.sympatico.ca/g.boudreau/CarbCleaning.html

Though I know little to nothing about carbs, I will second the PB Blaster. Best stuff ever for freeing up anything. It's all I use, at home and at work.

-Holiday wrote:here is another writeup on carb cleaning that i kee bookmarked:

http://www3.sympatico.ca/g.boudreau/CarbCleaning.html

thanks for the wonderful references... i am in the middle of digesting all of them. ill post an update this weekend (hopefully).

thanks guys!