Topic: 76 550f question about one plug running rich

[skarbakka]

Hi All,

First of all, I want to thanks to everyone that has helped me get my 550f up and running.  I have managed to sort out so many issues with this wonderful forum.  I just put in a pair of progressive front springs in my last attempt to fix some wheel hop.  First, my rim wasn't true, then the oil was too heavy, now after the springs, I finally have a great ride.  Doesn't feel like riding a cement block anymore.  Really shows how nice these bikes can feel to ride.

Now for my last, (hopefully for a while) question to pose to all you honda gurus out there. I am still running rich on one plug, old #2.  The other three are as near to perfect as I can tell, but #2 just won't listen to reason.  Therefore, I am considering putting ONE hotter plug in place, or fiddling with the carb to try to iron it out.  Unless anyone can think of another reason why #2 won't stop its sooty nonsense, I would appreciate some advice.  The carbs have been cleaned/parts replaced and tuned.  The bike runs pretty smooth with no hesitation, I just don't know how I should approach this until I do a complete restore/rebuild this winter.

Looking forward to your responses

[TwoTired]

Is the compression the same for all cylinders?

Vacuum synced carbs?

What parts did you replace in the carbs?

Were the main emulsion tubes cleaned?

Were the jets properly drilled?

[skarbakka]

Thanks, TT for getting back with me.  Here are some answers:

Is the compression the same for all cylinders?

I must apologize for my stupidity, but I have yet to check this component.  Everything seemed to working so well, I skipped this to avoid finding out bad news.  I need to pick up a compression gauge and find out.


Vacuum synced carbs?

Yes, the carbs are syned, but not air screw adjusted. Just at manufacturer's specs.


What parts did you replace in the carbs?

I got one of those seal/oring/needle replacement kits from Honda.


Were the main emulsion tubes cleaned?

I am pretty sure I cleaned everything very well, especially the emulsion tubes.
 

Were the jets properly drilled?

Another apology.  I don't know how to drill the jets, so I didn't so that before I put everything back together.  Now I am starting to worry about more problems to come. Especially in the form of taking off those carbs again.

[rshelbert]

I just went through this with my 75 550f.  I went through the whole list of things and could not figure it out.  My problem plug was #1.  It ended up being the emulsion tube under the main jet.  It was clean but apparently it was worn or damaged in a way I could not tell.  To figure this out I changed one internal part at a time from carb 1 to carb 4. (I was lucky on it being carb 1 as I didn't have to remove the carbs to do this.  I now have carb 4 running rich, so I haven't fixed the problem but at least I know what it is.  I have ordered a new set of carb kits and needle kits for the carbs in a hope it will resolve the problem.

With that said my bike only fouls plug 4 but the bike still runs overall rich between 2-3k rpms.  It burns the carbon off pretty quick once you get over 3k though.  I am honestly not sure why and am hoping the carb kits will resolve this (or at least let me be able to tune it).  Maybe this will help you in some way, but its something too look at.

[number13]

I had the same rpoblem onmy bike. The #3 carb
fouled plugs no matter how much I twiddled it.
The problem ended up being a clogged emulsion tube.
I cleaned it out and never had the problem again.
You mention you cleaned yours, so if they are still
clean you may have a worn needle. Also inspect all
parts carefully since previous owners of these old bikes sometimes
mix-n-match parts from other carbs.

[skarbakka]

Thanks much for your responses.

I replaced the needles when I did the rebuild.

Is it possible to get to the emulsion tube without removing the whole carb assembly?  I would hate for it not to be the problem after taking those damn things out again. If mine is clean, but damaged, where can I get a new one?

Has anyone tried using a single hotter plug to remedy until the season is over?  I want to start cashing in on all those gas saving opportunities that motorcyclers have at their fingertips and ride...

[andmoon]

I wonder if 1 float set too high can do that.

[skarbakka]

Yeah, what would one float being too high (or conversely, too low) do?  Does anyone have a full proof way of taking apart an interior carb without removing the whole lot?

[TwoTired]

Is it possible to get to the emulsion tube without removing the whole carb assembly?

It's "possible".
Remove all carb bowls
Remove main jet
Now you can see one end of it where the main jet was.  The other end is in the carb throat.  That's also where the slide needle orifice is that you do not want to damage.  It's also where you have to push the emulsion tube so it can exit out where the main jet was.  If it's clean, it might come out easily.  I usually have to knock then out with a wood dowel.  Of course, the slide needle is in the way for that.  So, the carb tops have to come off and the slides have to be removed so the needles can be moved out of the way of the wooden dowel punch so the emulsion tubes can drop out the bottom of the carbs to examine/clean.
So, it *is* possible.

Are you still sure you cleaned the emulsion tubes?

Has anyone tried using a single hotter plug to remedy until the season is over?  I want to start cashing in on all those gas saving opportunities that motorcyclers have at their fingertips and ride...

A hotter plug won't cure a rich mixture delivery.  It may help mask the problem a bit.

The machine will run right when all it's needs are met.  Either live with the sick machine, fix it, or (shudder) pay someone to do it for you.

By the way, I don't advocate drilling jets.  But, some people do and do it badly.  My question was meant as fishing for shody workmanship/repairs.

Cheers,

[skarbakka]

I really want to believe that I cleaned the emulsion tubes well. I even remember sending compressed air through them til they whistled. Is there any test I can do to make sure it is coming from the carbs before I dig in? 

[TwoTired]

There are like 10 holes in the tube sides, that let air into the fuel mix to form a froth.  That's why they are called emulsion tubes.  If some of these holes are blocked, the fuel mix gets richer due to less air.

Sightless cleaning is hit or miss.  If you didn't SEE they were clean, then you are only guessing.  I suppose that's one difference between a fact and a belief.

Unfortunately, the bike regards facts as more important than beliefs.  At least that's what they told me during my last commune.  Ask any "Iron Horse Whisperer". 

Is there any test I can do to make sure it is coming from the carbs before I dig in? 

Yes.  You could read the spark plug deposits.   

Don't feel too bad.  Some people clean carbs three or four times before they get truly clean.

Cheers,