Author Topic: Yet another 550 carb question by someone who should know better, but...... (Read 5053 times)

jsaab2748 · « **on:** July 31, 2007, 06:15:28 PM »

The last operation of my (totally stock) 550 k0 restoration was rebuilding the petcock,
adding fuel, and turning the gas on. Dwell is correct, timing is correct,
valves adjusted, cam chain adjusted, carbs thoroughly cleaned and new
o rings installed. Bench sync'd. Float level meticulously set to spec. Set the choke, turned on the ignition, and hit the starter. What I got was not what I expected. Extended cranking time, and a very rough and RICH running engine that wont idle, and won't even start unless the throttle is 2/3 open. And of course, black fouls the plugs almost immediately. The thing had to be flooded before I even cranked the
engine. The bowls do not leak out the overflow tubes, everything stays
dry. There is fuel in all the bowls. My question is, can anyone point me towards a particular trouble area in the carbs? Hell, it may not even BE
carb related, but I can't look at the thing objectively any more.
And I thought this stuff just happened to other people

As always folks, your input is greatly appreciated.

TwoTired · « **Reply #1 on:** July 31, 2007, 06:55:48 PM »

Is your choke on? Do the butterflys open fully?

Are your slow jets clear?

Did your main jets fall out?

Did you put the jet spring clips back in?

Did you clean the emulsion tubes?

What setting for the air screws?

Are they still Honda parts in the carbs?

What float level setting did you use?

Did you take the rag out of the air filter box? Evict the mouse nest? Use a new air filter?

Cheers,

aj · « **Reply #2 on:** July 31, 2007, 08:43:15 PM »

my buddy has the same problem with his 550 he went over everything just like you did so im curious if anyone has any answers. his bike really stumbles on acceleration and hes not even driving it anymore. it sucks cuz he has an awsome 550. $:-\$
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jsaab2748 · « **Reply #3 on:** August 01, 2007, 04:50:55 AM »

Quote from: TwoTired on July 31, 2007, 06:55:48 PM

Is your choke on? Do the butterflys open fully? ------------yes
Quote

Are your slow jets clear?----------cleaned them out good
Quote

Did your main jets fall out?-----------new o rings and.......
Quote

Did you put the jet spring clips back in?------------yes, clips all in
Quote

Did you clean the emulsion tubes?---------yes, and soaked the carbs in berrymans
Quote

What setting for the air screws?-------can't remember at the moment, but remember setting them to recommended 1-1/2 (?) out
Quote

Are they still Honda parts in the carbs?-------all o.e., not sure about needles though.
Quote

What float level setting did you use?........again, don't remember, just know it was set to what's called for, (22 M.M.)?
Quote

Did you take the rag out of the air filter box? Evict the mouse nest? Use a new air filter?---------He got burned out of there during the previous engine/carb fire started by the previous owner, who, by the way ,was having carb problems with the bike as well
Quote

Cheers,

It acts like it's drawing too much fuel by just simply
cranking the engine. Could bad plugs maybe an issue? These looked ok
before I started, but they aren't new...

clarkjh · « **Reply #4 on:** August 01, 2007, 05:05:42 AM »

Do you have the stamped number on the jet needles? My 74 still fouls a bit when running the transition from idle to needles and I'm going to drop the needle to the last grove. Weak spark can cause fouling. Pull the air filter out and try starting. Did you mod the engine or exhaust any? I set mine at 21mm when I thought it was overflowing, ended up the petcock was leaking out of every place possible and then some.

Good luck on finding the problem.

James

jsaab2748 · « **Reply #5 on:** August 01, 2007, 03:29:48 PM »

After thinking about it for a while, I am considering draining all the bowls, then opening the petcock just long enough to fill the bowls about half way back up. Then trying to start engine again with the fuel turned off (with new plugs installed) and see if the thing will
start and rev cleanly, if only for as long as the small amount of fuel
in the bowls lasts. I figure if it's a float level issue, this should confirm it. If that doesn't help, I'm thinking of removing the air filter box, draining the bowls again, and not allowing them to refill at all.
Then spray a small charge of starting fluid in the thru the rear of the plenum chamber and repeat the starting process. If it STILL doesn't
rev cleanly, it aint the carbs, but somewhere else. What do you guys think? Oh yeah, I forgot to mention earlier that EXCEPT for a 555cc
bore up kit, the bike is completely stock, unless I find it has the wrong
needles in the carbs. Stock air filter set up, 4 into 4's and stock jetting. The air filter is a genuine new Honda part.

chippyfive50 · « **Reply #6 on:** August 01, 2007, 04:05:48 PM »

Are all plugs fouling? I just rebuilt a CL175 and put the slides in backwards, needless to say it ran like ass until you opened it up. I also found a float taking on fuel was a contributing factor as well.. .. my 2.

jsaab2748 · « **Reply #7 on:** August 01, 2007, 04:43:48 PM »

Quote from: chippyfive50 on August 01, 2007, 04:05:48 PM

Are all plugs fouling? I just rebuilt a CL175 and put the slides in backwards, needless to say it ran like ass until you opened it up.

I did that on an old cl 175 years ago. It was one of the first things I thought of in my current situation, but the 550 carb throttle valves are not right and left sided like the 175, so they won't fit backwards.

750essess · « **Reply #8 on:** August 02, 2007, 12:40:31 PM »

It could be the passage from the carb thoat to the main jet/ emulsion tube. Try spraying carb cleaning in the hole in air cleaner side of the carb throat. It should come out the main jet. If not, you could try a wire to clear it or what I usually end up doing is taking them clear apart and push the whole mainjet tube out from the slide side. It the piece that the needle goes down through. You will probably find that it is all gummed up in there.

number13 · « **Reply #9 on:** August 02, 2007, 01:13:14 PM »

Just to double check here, did your carb rebuild
include remiving the emulsion tubes? I had a
similar problem, but only on one cylinder. The
#3 jug ran way rich no matter how much I twiddled it.
I finally got in there and pulled all four emulsion tubes and
found two in pretty good shape,one partially clogged,and you
guessed it, #3 completely caked with gunk.
Cleaned and polished them and was rewarded with
a bike that ran like new!

CB500_k2 · « **Reply #10 on:** August 02, 2007, 03:03:18 PM »

Sorry to kind of high jack this thread, but, how do you remove the emulsion tubes from the carbs? This was the only step I did not do as I rebuilt my CB 500 and 350 carbs. Thanks and I hope this helps other new to CBs.

number13 · « **Reply #11 on:** August 02, 2007, 03:15:43 PM »

To remove the emulsion tubes you must completely disassemble
the carbs (again). The tubes can be easily pushed out using something
soft, such as a chopstick, so you don't deform the brass.
Push them out from the top of the carb.

TwoTired · « **Reply #12 on:** August 02, 2007, 05:22:03 PM »

The emulsion tubes come out where the main jets sits. if they don't fall out (HA!) then they are pushed out from the slide openings. You have to to remove the slides for that to happen. It can be done without removing the carbs from the bike or separating the carbs. But, there is mechanical prowess required to do so. In the bike is actually faster than removing the carbs when you know what you are doing. But, it is a personal choice.

Cheers,

m00ntan · « **Reply #13 on:** August 02, 2007, 06:12:48 PM »

You're confusing me. Is emulsion tubes the slow jet seat?

edbikerii · « **Reply #14 on:** August 02, 2007, 06:24:53 PM »

On 77-78 550 K models, the slow jets are pressed in, and have built in emulsion tubes. I would not say it is impossible to remove the pressed in slow, AKA pilot, jets, without removing the carbs from the bike, but it requires some "prowess" as TT said, plus a whole lot of cursing, tiny hands, tiny vise-grips, etc.

The emulsion tubes behind the main jets are the hex-head tubes that the main jets screw into. 8mm open end will get them out, once the float bowls are off. Getting the float bowls off without removing the carbs from the bike is tricky too, but doable if you've got a really stubby philips screwdriver.

Personally, I think I'd have a hard time getting the pilot jets out with the carbs in place. The floats and main jets, I'd readily do, and with lots of practice it wouldn't take me more than 30 minutes or so. If new, allow an hour or two.

BTW, the all need to be cleaned out, pilots and mains.

TwoTired · « **Reply #15 on:** August 02, 2007, 09:30:47 PM »

My response was directed to a cb500 owner (thread hijacker) with the early style Keihin carbs.

I don' remember what bike you have moon. If you have the PD style listen to Ed.

Cheers,

edbikerii · « **Reply #16 on:** August 02, 2007, 09:41:07 PM »

Oh, yeah, sorry. I didn't realize it was hi-jacked. I thought we were talking about 77-78 PD46 style carbs. I really don't know anything about the earlier model carbs or the 77 550 F model carbs first-hand. I'd definitely listen to TT's advice on the earlier carbs[Edit], and the 77-78 PD46 carbs too[/Edit]. The 77 and 78 PD46 carbs are significantly different.

Quote from: TwoTired on August 02, 2007, 09:30:47 PM

My response was directed to a cb500 owner (thread hijacker) with the early style Keihin carbs.

I don' remember what bike you have moon. If you have the PD style listen to Ed.

Cheers,

jsaab2748 · « **Reply #17 on:** August 02, 2007, 09:59:40 PM »

Well folks, I did clean the emulsion tubes during my carb service. Every piece was removed and soaked in carb dip (except the rubber parts of course) and then washed in hot water and meticulously dried with compressed air thru ALL passages. Something I discovered today when I removed the float bowls again was that I followed the previous owner's mistake of putting the main jets back in upside down. The chamfered hole in the main was installed upwards, towards the emulsion tube. Seeing this was the case on
all 4 carbs, I simply changed the o rings to the opposite groove in the jet, flipped the jets over and reinstalled them correctly. Now the engine starts more redily, but is still seemingly running rich. It will rev, but sputters irratically, and with the plenum chamber removed
and engine runnig, a spray of air/fuel can be seen exiting the carb intakes when the throttle is goosed a little. I still think this is a carb issue, but haven't yet figured it out. Float level? None of them overflow, but can it be too high enough to effect performance? I measured the bowl contents of each carb and they all contain virtually the same amount of fuel. Does anything else come to mind that might be installed backwards or adjusted incorrectly to cause this type of behaviour? Next thing I'll look at is needle taper, as I have a few parts carbs to compare to. I will post any results I get, and thanks for everyone's input so far....

rdub3017 · « **Reply #18 on:** August 03, 2007, 12:35:28 PM »

jsaab,

I am having similar problems with my 76 550F...as posted by my friend aj. i have all new seals in the carbs, stock settings, clean emulsion tubes, and stock internal parts. 1/2 used to run rich and i took the bike to a mechanic and now it runs better but 2/3 are now running rich.

I am now wondering if this problem is an electrical issue?? (i have new points and have swapped condensors, timing has been checked twice)

Ryan

jsaab2748 · « **Reply #19 on:** August 03, 2007, 03:23:40 PM »

I will be sure to post results when I get them. I have so much money sunk into this thing, I can't quit till it's fixed

05c50 · « **Reply #20 on:** August 03, 2007, 06:36:34 PM »

I had a similar problem on my 77 550. The carbs had been completely cleaned,the passage ways were checked,jets all clear,but it still ran rich enough at idle to foul the plugs. After many months of attempts to lean it out,I found the problem....the inside of the emulsion tubes were corroded away. When I looked into the tubes with a small light,I could see a rough, corroded surface on all four tubes. I replaced the tubes and now it runs great. I also found that a slightly discharged battery will make it run rich. Enough power to crank the starter, but not enough for full coil output.
...Just some of my experiences. Paul

anparkinson · « **Reply #21 on:** August 09, 2007, 12:38:46 PM »

I had a similar problem on my 550K3 when I got it but only on No4 cyl - always running too rich and flooding. Turned out that the float was on upside down. Maybe worth checking......

jsaab2748 · « **Reply #22 on:** August 16, 2007, 09:02:16 PM »

I just got back from vacation, thanks for the suggestions. I did check the emulsion tubes inside and they look pretty good. The floats are all in right side up too. I just took carb number 1 apart
and checked the needle and clip position and they both are correct.
One thing that bothers me at this time is that, even though the float level is set at 22 m.m., and the carbs are not leaking out the drain tubes, is it possible for the fuel level to STILL be too high?
Seems like this would cause a rich condition, and might cause issues with the emulsion tubes functioning correctly. As close as I can tell, the level of fuel in the bowl tops out around 1/8 inch (or less) from where the gasket surface of the bowl meets the the bottom of the carb. Any thoughts? Still shootin in the dark.

jsaab2748 · « **Reply #23 on:** August 21, 2007, 05:54:14 PM »

Thought I'd post my"fix"results for my overly rich running 550 K0 carbs. The excessively rich mixture was caused, from what I can tell,
by float levels being slightly too high. I reset all the floats from the
spec. 22 mm. to 23 mm, and it makes all the difference. Maybe I let the floats press too hard on the needles during adjustment(?) I suspect that
the slightly high level of fuel in the bowls was causing issues with the
emulsion tubes being submerged too deep in the fuel, covering up all the crossed drilled holes. This is only a guess, but it sure starts easy and runs smooth now. It ran clean enough to create condensation in the exhaust (on a hot night). Don't know how scientifically correct my
conclusions are, but this one operation sure made things better.

m00ntan · « **Reply #24 on:** August 26, 2007, 07:58:29 PM »

BTW: found my emulsion tube. Thank you.

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Author Topic: Yet another 550 carb question by someone who should know better, but...... (Read 5053 times)

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