Topic: CB550 running rich...

[Super Sport 550]

I've got my CB550 running good down low (yes, the airbox is hooked up  ), but as soon as I get on the gas much it starts running really rich. It will blow a little black smoke, misfire, and slow down.

Is there some sort of an adjustment on the carbs for mixture at throttle? I know that most of the bikes I've worked on have a clip in the slide so that you can move the needle relative to the slide, but these carbs are very different from those. Seems like there would be an adjustment of some sort for this, though...

Thanks!

[78_SaltLick]

dang dont know about the supersport's, but the 550's have a screw on each carb that can lean out the mixture. Turn it counter clock wise. I have a 550 and the stock settings are 1.5 turns out from lightly seated. best bet is to reset them to stock, then turn them each counter clock wise out 1/2 turn and see if that doesnt help you. You can access two of the screws from one side of the engine and two of them from the other side. Im sure people will ask you other questions like have you had a recent tune up, and is your exaust stock or a 4 into 1. Trying pulling out your air filter and see if that doesnt make a difference first. If it does you can then try adjusting the screws on the carbs if that doesnt make a difference.

[Rushoid]

This might be a dumb question but are you sure the choke is opened all the way?

Don't know about the 550 but my 750F has the non-adjustable slides too. Once I got mine cleaned out I adjusted them like SaltLick said and it runs great.

Of course there's always the ignition side too... timing, points, etc.

[Super Sport 550]

Thanks for the responses!

The choke is definitely open all the way.

I will try adjusting those screws. I know the ones you mean and I suspect they are poorly set (they are all at visibly different settings).

Dumb question: What is different about the Super Sport? Is there really anything different besides the lettering on the side? I don't know much about these bikes.

I do have a 4-1 pipe (What's left of one, it's really more of a straight pipe at this point. All of the insides are rusted right out). It has been on there for probably 25 years.

I suppose you might say I've had a sort of tune up recently... I bought the bike out of a junkyard not running. I've got it running and have put 25 miles on it just beatin' around the back... Don't really have the tools to tune it up properly.

I'm just trying to get the carbs working. I've set the timing and dwell (statically, I don't have a timing light) and adjusted the cam chain.

Thanks!

[Rushoid]

The Super Sport is like having an amplifier with knobs that go to 11. It's just one better!  The SS has 4-into-1 exhaust, dual front disks and disk rear brake, different gearing (?), different carbs and some styling differences. Not sure if there's anything different about the engine or anything else. I've only had mine for a few months and I'm still learning myself.

Do you have a Clymer's manual? I've found mine to be invaluable while trying to resurrect my bike. To get mine running I put in new plugs, points, condensers, plug boots, and cleaned the carbs.

Glad to hear you rescued her from the junkyard. Sounds like you're almost there!

[Super Sport 550]

That is weird. My bike has only one disc up front and a drum in the rear.  It has all the SS markings and the 4-1 exhaust, though...

No, I don't have a manual. This is kind of a low $$ project. I've been kind of guessing my way through, but I may have to get a manual.

[Rushoid]

Well, again, mine's a 750. I don't know a thing about the 550. Yours might be correct. Research some of these old threads. I'm sure you'll find everything you need to know. Sorry I don't know more but if you post your findings, then I will 

[TwoTired]

IF they are still the supersports carbs you will find a stamping of 069A on each carb body.

The screws on the side of them really only effect idle to maybe 1/4 throttle.

The slide needles ARE individually adjustable with clips.  The slides have to be removed to do this adjustment, and a carb sync is mandatory afer doing this.  This will change the mixture from about 1/4 to 3/4.  And you will meed tools to fix this.

The main jet dominates the mixture from 3/4 to WOT.

A clogged or partially clogged air filter with make the mixture rich with increasing effects as more air is attempted to be drawn through it.  This acts as partial choke.

The choke lever is all the way down for the off position.

An open exhaust will also change the carb mixture demands.

All three years of the CB550F supersport had single front disk brake and drum rear and 4 into 1 exahust.

If you are serious about getting the bike running correctly, you will get a manual.

[Super Sport 550]

Okay, how do I adjust the slide needles? Now i know they are adjustable, but how are they adjusted? I have no clue how these carbs are put together.

I found the information about the different stuff on the SS. Seems that the K model was the standard one and the F model was the SS. The information about the differences can be found at http://sohc4.us/?q=node/29

The air filter is not clogged. The choke is off, like I said.

I really would like a detailed description of how to get to the slide needle adjustment. Assume that the carbs are sitting on the workbench, what do I do next? I assume that you remove the covers (the ones on to of the carbs that are shaped sort of like coffins and are held on with two screws), but what next? I'm a tiny bit clueless here... Most of the bikes I've worked on are either single cylinder with a simple cable pull hookup or have CV carbs.

[TwoTired]

The air filter may not be clogged.  But, it may be restrictive.  Test run without it to find out if this is so.

Okay, from memory.
With the top cover off the carbs, you will see the common actuating shaft that operates all the slide lifters. Bend the tabs that are on the bolt for the lifters and remove the bolt. (You just lost all synchronization to the other carbs.  And you can now expect idle and other performance issues until the carbs are synched again with manometers.)
Next, remove two small crosspoint screws deep down at the base of the slide tops.  This frees the slide actuating mechanism and it will pivot up and out of the way, allowing the slides to be withdrawn or just the needles by themselves.  The needles have a clip on them to control the depth into the throttle jet, relative to slide position.

as soon as I get on the gas much it starts running really rich. It will blow a little black smoke, misfire, and slow down.

Final warning.  A restrictive air filter will exhibit these exact same symptoms just as choke application would.

Cheers,

[Rushoid]

TT, I bow to your mastery of all that is SOHC! 

So do I understand correctly that, on my 750F, if that common shaft and the carbs have never been seperated (still has the marking paint on all of the fasteners), and the slides are all in the same position, then my carbs are "synched?" When I took mine off to clean them, I left them all together as one unit. I took the top covers off just to check in there but I didn't adjust anything. All my efforts were from the floats up. It runs great now but with all the talk of synchronizing carbs I was wondering if I still needed to do that to get the best performance.

[TwoTired]

Mastery, no.  But, some knowledge, yes.

Bear in mind the 78 750F carb are of different design than the CB550F.

Given that, all I can say is that if you didn't take it apart, you didn't change the sync.  Vibration and wear factors can change the relative slide positions amoungst carbs from when is was synched at the factory or service center.
 They only way to check if they are still in sync is to check them with manometers.  And, I do this at each tuneup interval (3k miles).

As an example, my 74 Cb550 Honda didn't change its own synch for 5 years of riding.  I almost began to skip the check.  But, then I found it needed adjustment, which was also stable for a couple years.  I'm unable to predict now when they will go out of synch.  But, if it doesn't idle smoothly after the other tune up items are addressed, the manometer check usually shows and adjustment is needed.  Then it is all smooth again for a while.

Cheers,

[Rushoid]

Thanks for the info, TT. A little knowledge goes a long way towards my confidence with this bike.

Just noticed you're in Milpitas. How's life in the Bay Area? I was stationed in Alameda in the early 90's. Now I'm "back home again in Indiana." I miss that area - beautiful country even when it hasn't rained in months  Don't miss the traffic though.

Thanks again!

Lee

[Super Sport 550]

Well...

It is still rich with the air cleaner removed. I tried that before I even started this thread. I'm a newbie, but not that new... 

I tried adjusting the screws and nothing happened.

I will try the adjusting the slide needles and see what happens.

Thanks!

[jimbir]

Don't buy the Clymer manual for the 550. Download the manuals available in the SOCH/ 4 Bikes forum. The Clymer manual that the dealers are selling for $35 is nowhere as complete.