Topic: The Green Dragons maiden voyage cb550

[78whiteorbs]

Over winter I woke this bike up from a gentle sleep.
Rebuilt carbs and ultrasonically cleaned everything.
Victory lap to let the dragon quench it's thirst ... Ran pretty well below 3k felt kinda boggy and wasnot purring nice and sweet as it was with the air box off at idle. Got home and pulled plugs and as suspected all 4 carbon fouled.  I haven't  even reset the timing reset the point gap or anything mechanically other than clean carbs replace a faulty starter
and install airbox with an iffy  at best filtfilter.She ran fine all nice and even at higher rpms . Also notice some idiot (me :-) ) used 2 7es  plugs and 2 8es  plugs.
 
This bike revved and idled so smooth with the air box off I was kinda 8n disbelief.  Plan is to check the ignition system install new plugs , sync carbs and see if she fouls again . Suspect possible float level may be a touch to high causing a slight rich condition. Any other thoughts?  It's a 76 cb550  and has very low miles and excellent compression.  Had original  uncrating checklist and original sales receipt under the seat from when new.

[78whiteorbs]

Because who doesn't like pictures

[Stev-o]

Buy her some new points, orbs. She deserves it.

[SOHC4 Cafe Racer Fan]

Why not change to an electronic ignition and ditch the points?

[78whiteorbs]

Why not change to an electronic ignition and ditch the points?

No real advantage if you know how to set points in my opinion. Nothing you can fix on the side of the road with a faulty electronic ignition. I did have a pack on an xs650 that actually belonged to paMco  Pete and was his rider for 15 years that the engine was due for a top end but the pamco sparked so hot it would zap right through fouled plugs that wouldn't have left a stocker stranded hundreds of miles prior so it sold me on his xs650 setup. It did have upgraded coils as well to though...

[scottly]

Nice looking bike, whiteorbs!!!!! BTW, sooty plugs are caused by carb problems, not ignition: no spark, no fire, no soot.

[78whiteorbs]

Nice looking bike, whiteorbs!!!!! BTW, sooty plugs are caused by carb problems, not ignition: no spark, no fire, no soot.

My least favorite thing about a 550 , pulling and replacing carbs
 I'd rather wrestle 750 carbs on the rock hard 40 year old manifold intake boots than take those carbs off. Suprisingly My 350f is cake. I use the same method of ratchet strapping the airbox all the way back but on the 550 just seems more the chore.

SCOTTY I was under the impression a weak ignition could contribute to overly rich condition by incomplete combustion..or miss firing at lower rpms

[scottly]

SCOTTY I was under the impression a weak ignition could contribute to overly rich condition by incomplete combustion..or miss firing at lower rpms

Sorry, but your impression is incorrect. A rich condition can cause carbon fouled plugs, which can cause a weak spark, but a weak spark from an ignition problem can fail to fire an otherwise proper mixture, which leaves a wet, but soot-free plug. It's kind of a "which came first, the chicken or the egg" diagnosis.

[78whiteorbs]

SCOTTY I was under the impression a weak ignition could contribute to overly rich condition by incomplete combustion..or miss firing at lower rpms

Sorry, but your impression is incorrect. A rich condition can cause carbon fouled plugs, which can cause a weak spark, but a weak spark from an ignition problem can fail to fire an otherwise proper mixture, which leaves a wet, but soot-free plug. It's kind of a "which came first, the chicken or the egg" diagnosis.

I am tracking with you . Who among us hain't been wrong in there thinking? I know I have that's why I really like this community here. I applaud your polite correction in my theory. Makes perfect sense.

Now why the carbon fouling/ Rich condition in freshly rebuilt carbs. I faced this once before and never solved it.

[78whiteorbs]

Another thought  I had was it was being choked for air thus Richening  the mixture. There is a very old air filter in there and though I did blow it out with air I doubt the airflow is not being  restricted and effected because of it. A new one is on the horizon. It was also peculiar to me no choke was needed from a cold start and in fact it would immediately kill the bike. From past 550 s even on a warm day in spring they liked to start on the choke and be warmed  up a little...

[mrfish2]

Another thought  I had was it was being choked for air thus Richening  the mixture. There is a very old air filter in there and though I did blow it out with air I doubt the airflow is not being  restricted and effected because of it. A new one is on the horizon. It was also peculiar to me no choke was needed from a cold start and in fact it would immediately kill the bike. From past 550 s even on a warm day in spring they liked to start on the choke and be warmed  up a little...

That's exactly what's happening to mine right now, right down to the old air filter. What kind of gas mileage are you getting on yours? I'm only getting about 60 miles to a tank.

[78whiteorbs]

On the first tank now. Mr. Fish did you get a rebuild kit from 4-1 . I got new needle valves and seats and read some were they were a little different and you had to reset the float height. I thought I specifically recall doing just that but there. Is a slim chance I didNt.

Gonna go over everything once more and then ugh pull the carbs once more and quadruple check all the math in there.
Lemme know how things go with your little challenge.

[mrfish2]

I got rebuild kits from Cruzinimage on Ebay (it was a set of 4 for 45 bucks, seemed like a pretty good deal) and they ended up being Napco brand kits from Japan. I used everything from the kits EXCEPT the needles, and yes I ended up adjusting the float levels due to the new seats and float needles. My exhaust is fairly rusted out in the mufflers, but I've yet to do any plug chops to see how everything is being affected. One hypothesis I've got is to step down a size in pilot jets, but I'll wait till after some plug chops to determine that.

[DH]

I'll ad this. My experience with my 550 carbs is that proper float level is CRITICAL. After that,  FUEL level is critical,
which means to do the clear tube method to verify how much fuel is in the bowls. If it is too high for ANY reason,
the engine will act stupid. It can cause hard starting, the plugs get carbon fouled, It'll run seemingly good for a bit, then rough, the idle will change etc, the whole time
you're trying different things and adjustments and all of them to no avail. The clear tube method will eliminate any
guessing as to whether there is too much fuel in the bowls. Once that is rectified (if it's off) you can eliminate that
particular area as the cause of a running problem. And since you have done a thorough tune up and have the carbs
otherwise clean (completely) you should be in the ballpark. It's best to use original honda parts, and if possible, re use everything
except gaskets and o rings. If you find it runs better without an air cleaner, replace it, as it is restrictive.
That alone will cause an overly rich mixture as well.  Doing this fiixed my bike, just passing it along

[78whiteorbs]

Good food for thought. This is were my gut is telling me to look as well. After new seats and needle valves I was having carb one and two puking feel intermitantly. After rapping on the float bowl it'd stop but if the engine wasn't running and tehe fuel valve was left open it would flare back up... I thought this was indigenous  to most old sohc bikes but my cb750 carbs were never as tempremental.

[mrfish2]

Everytime I come to a stop I turn my petcock off just so it won't piss any fuel out.

Did you check your fuel levels via the clear tube yet whiteorbs? I know when I first started my bike up after rebuilding the carbs again it carbon fouled the plugs extremely quickly, then after readjusting the float height to get the fuel level 3-5 mm below the gasket surface it quit fouling the plugs. Still runs rich, but now I can rule out float heights.

[PeWe]

Really good looking bike!

I had some problems with my CB750 at my last restore
# Sloppy adv springs that caused way too early full advance.  - Check with timing lamp that full advance kick in after 2500rpm. I guess closer to 3000 on a CB550

# Flowing floats. It took time for me to listen to the pros on this site that wrote about checking flots. Clear tube showed the real thing. Mesure floats is not everything, a good start. The valves must close in time.

¤ Edit: I forgot the bad fuel lines I had with my new carbs this year. Bad quality hose that collapsed and caused no fuel to 1-2  (2 fuel inlets, 1-2, 3-4). I bought better hose that withstand fuel with ethanol and methanol, Gates Barricade (for fuel injection). Very tight fit, both 6mm and 7,9 mm versions. No need of clamps for no leak, only to keep them fixed. I have no clamps on the 2 hooses from tank when the tank will be removed soon during the final jetting with Dyno. After that my new 4-4 and new tank will enter the bike.

# The worst thing was my new ignition wires. One of them had intermittent function that tricked me to hear lean engine or sometimes jerky engine on low rpm that can be seen as too rich. My carbs were in the jetting phase so it was easy to make wrong decision. Dynatek suppressed carbon wires.
Copper wires with std NGK 5k ohms caps is better when the caps do not need nuts on plugs that will not fit HONDA plug wrench.

I'll have one extra sets of wires with caps just for sure to check with when problems occur.

I have new Points TEC, I think same model for CB750 as 550. Hondaman ign module (no need of condensors). Dynatek 5ohms coils. Engine revs fine over 9000rpms

[DH]

http://forums.sohc4.net/index.php/topic,140837.0.html

Whiteorbs Just to add to whats been posted,
not sure if this applies, just a suggestion. I got tired of taking those damn carbs off when i did this

[Duanob]

If you haven't touched the points, etc it sounds like a 3000 mile tune up is in order first and foremost? Then onto the carbs. While I believe in electronic ignitions, if it runs like crap before the upgrade chances are it will run like crap after. get the problem sorted out first with OEM parts i.e, tune up, carb clean, vac sync, etc. then start to upgrade.

[scottly]

Be aware that after correcting any rich carb problems, symptoms may persist if the spark plugs are still carbon fouled. Either burn the carbon off with a propane torch, or replace with new. (I prefer burning the carbon off, until I know the problem is solved)

[78whiteorbs]

http://forums.sohc4.net/index.php/topic,140837.0.html

Whiteorbs Just to add to whats been posted,
not sure if this applies, just a suggestion. I got tired of taking those damn carbs off when i did this

Brand new viton tipped needle valves and brand new valve seats. gonna check the clear tube method and see where the level is the reset the floats in relation. why brand new seats and rubber tipped valves would not be sealing is beyond me though  . The action on the floats was perfect   no binding at the pin or anything.  Could be as simple as to hi a fuel level thougt we"ll see...

[78whiteorbs]

Be aware that after correcting any rich carb problems, symptoms may persist if the spark plugs are still carbon fouled. Either burn the carbon off with a propane torch, or replace with new. (I prefer burning the carbon off, until I know the problem is solved)

I always do this or use glass bead

[78whiteorbs]

Everytime I come to a stop I turn my petcock off just so it won't piss any fuel out.

Did you check your fuel levels via the clear tube yet whiteorbs? I know when I first started my bike up after rebuilding the carbs again it carbon fouled the plugs extremely quickly, then after readjusting the float height to get the fuel level 3-5 mm below the gasket surface it quit fouling the plugs. Still runs rich, but now I can rule out float heights.

Mrfish where did you get this figure >3 to 5 mm below?
also I am always suspicious of those orings that seal the press in idle jets ...maybe its late and I am thinking of another bikes carbs though.

[78whiteorbs]

If you haven't touched the points, etc it sounds like a 3000 mile tune up is in order first and foremost? Then onto the carbs. While I believe in electronic ignitions, if it runs like crap before the upgrade chances are it will run like crap after. get the problem sorted out first with OEM parts i.e, tune up, carb clean, vac sync, etc. then start to upgrade.

no intent on running anything other than points.
yeah a tune up is in order

[mrfish2]

Mrfish where did you get this figure >3 to 5 mm below?
also I am always suspicious of those orings that seal the press in idle jets ...maybe its late and I am thinking of another bikes carbs though.

I read that somewhere around here, can't remember where though. The pic below is where I was told was an accurate fuel level in the bowls.