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Author Topic: 1975 CB550F Lacks power! HELP I AM DESPERATE!!  (Read 4126 times)

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Offline ACVWguy

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1975 CB550F Lacks power! HELP I AM DESPERATE!!
« on: June 25, 2011, 10:38:06 PM »
I am at my wits end here. I'm all out of ideas, brutally frustrated, and just don't know where to go from here.

First to clarify, I am not new to working on engines. I spend most of my time working on cars but I recently bought a motorcycle to save on gas (just graduated from high school and don't have a lot of coin) and just have a little more fun. This is my first post on these forums, but I have spent hours a day for the last 3 weeks reading these forums (especially the FAQ) - just searching for answers, so I am by no means new.

So, about 3 weeks ago I bought this 1975 CB550F from the son of the second owner. The bike has 6700 original miles on it, never been tipped, always garaged, has original paint and seat in remarkable condition. The wiring is untouched and original - near perfect. The man I bought it from claimed that he rode it about 3500 miles in the last 8 years. When I bought it, it looked pretty neglected (not abused), but it was straight, so I spent an entire day polishing every surface and the bike came out looking so gorgeous I can't even explain without a picture. I got it for $850.

So After I got it started, I took it for a ride and found that it ran ridiculously rich and had absolutely no power. I brought it home and started taking things apart and adjusting and what not.

First things first, I adjusted the valves (.003" in and .004" ex - based on the advice of the forums), and replaced the plugs with NGK D8EA's. I then cleaned and gapped the points and regreased the rubbing block and cam. I set the timing with a timing light. After that, I took it for a ride. No change in performance. The bike pulled hard up to about 3500rpm, then lost power by 5000rpm and would not accelerated past 5000rpm. In 5th gear at 5000rpm, the bike would not go past 60mph. It's just gutless... worse than my gz250. I decided that it might be an inconsistent distributor advance mechanism, so I pulled it, cleaned it, and regreased it. After taking it for a ride, still no improvement.

So I dug into the carbs. I pulled them off and discovered that they were stamped 627B - carbs off of a 71-73 CB500. I thought that was odd. Anyway, I completely disassembled the carbs one by one and found that all of the rebuild items were new. O-rings were fresh, gaskets like new, and jets shiny. I pulled every jet, float, needle, slide, and float pivot and cleaned and polished with 0000 superfine steel wool. The carb bowls were spotless. The carbs are in such good condition that they still shine and have that pearlescent pink-green color to them. All of carbs had 40 pilot jets, 100 main jets, and the needles set at the 4th notch down. I removed the needles and set them at the 2nd notch down (as a CB550F would, not a CB500). I soaked the carb bodies in Chemtool. I then completely assembled all the carbs, and bench synced with a 1/8th drill bit. I polished the float needles and lapped them against the seat for a good seal, then set the floats. I then installed the carbs on the bike, set the idle air screws at 2 turns out, hooked up the intake (I should mention that this bike has the stock airbox and filter), and fired it up. I then did a full vacuum synchronization of all four carbs. Feeling like I covered all of my bases, I took it for a ride. No improvement.

I pulled the plugs and they were heavily carbon fouled, with a bit of a white ash on the electrodes. There is no oil fouling, just soot. After reading about the higher heat range of the D7EA plugs, I replaced my D8's with a new set of D7's. This made a difference in the plug fouling and start-up, but no help in the upper RPM range (5000+). I should also mention that all of the plugs are firing; however, I couldn't really measure how consistently with my timing light.

So to recap, here are the symptoms of my bike.

Turn on the petcock and ignition, and the bike starts on one kick. It usually doesn't even need choke. A little coaxing with the throttle for about 10 seconds and the bike idles down to 1100RPM smoothly and stays there, ticking like a clock. I take it for a ride and it runs smoothly all the way up to 3000 rpm, with very little sputtering and no popping. When I try to accelerate smoothly (no sharp pulling - no accelerator pump), the bike will begin to blubber at 3500rpm, getting worse as I approach 5000rpm. After I reach 5000rpm in first gear, The bike sputters a ton; however, it does accelerate, albeit gutlessly, with no pull or power to speak of. I shift at 7000 and the bike pulls good from 4k to 5k, then nothing. All through 3rd to 5th gears, the bike can't pass 5000rpm. I can't even make it up a long hill in 5th gear. With the throttle pinned at 60mph in 5th gear, the bike loses speed, slowing to about 50-55mph. The bike also guzzles fuel like none other. I just can't figure this out and I am at my wits end... never have I felt so frustrated and baffled.

Now to recap what I have done to troubleshoot:
-Cleaned and gapped the points (like new), greased the cam, set the timing with timing light.
-Replaced the plugs with NGK D7EA.
-Cleaned and regreased the distributor advance.
-Adjusted valves.
-Cleaned and polished the carbs parts (light rebuild -it really didn't need it)
-Set needles at 2nd notch.
-Vacuum synced the carbs.
-Set idle air screws at 2 turns out.
-Set floats as high as I could without allowing the carbs to overflow (I don't know how to actually measure the float depth)
-I also realized that I didn't clean all the emulsion tubes. I cleaned two of them but they didn't need it so I left the other two. The carbs are literally spotless.
-The exhaust is a baffled 4into1 header off of another CB (650?) Its got some sizeable dents. PO put it on to replace rusted out original exhaust.
-The carbs are 627B's (changed by PO for some odd reason) I found that stock is 069A's for the '75 CB550F.
-The coils look like new from the outside, and the plug caps have no weathering or cracks. The brass contacts inside the boots shine.
-The spark plugs all put out a strong blue spark.
-The battery is good and the starter starts the bike in less than a second. All lights work, including signals, and that odd tone that comes from the flashers. I doubt the issue is electrical as the charging system works correctly- I drove it into town for about 30 mins and had no issues other than the inability to pass 5000rpm.

Can somebody help me with this stumbling and lack of power or ability to pass 5000rpm? Sorry for the novel, I am just trying to eliminate any possible holes in my diagnosis. I am at a loss to this entire phantom issue. Any help or tips that I haven't already covered are much appreciated. Thanks in advance,

Austin

Offline Greggo

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #1 on: June 25, 2011, 10:50:07 PM »
Has the air filter been replaced?  Does it feel bogged down before you get to 5k?
« Last Edit: June 25, 2011, 10:51:43 PM by Greggo »

Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #2 on: June 25, 2011, 10:57:07 PM »
No, the air filter is quite possibly original, but it is like new. I tried the "remove the filter" trick to see if it ran better without it and the improvement was marginal at best. It definitely hurt low rev performance but didn't do much to improve the 5000rpm performance.

The bike feels perfect up to 3000 rpm, then quickly begins to blubber and by 5000rpm it is out of guts. Oddly enough, even though it is still running rich, it doesn't leave black smoke.

When the bike is not under load, it will rev right up to 9000rpm no problem, without a hitch.

Thanks,

Austin

Offline Greggo

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #3 on: June 25, 2011, 11:00:43 PM »
Don't rev your engine to 9k without a load on it.  Other than that, I'll yield to the experts with more experience.

Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #4 on: June 25, 2011, 11:56:49 PM »
Agreed ;) I was only seeing if it would rev smoothly and consistently past 5000rpm while it was sitting still and I got carried away. I wouldn't normally rev without a load at all it was just a small experiment. The engine was warm.

Anyone experience this condition before, though?

Offline TwoTired

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #5 on: June 26, 2011, 12:28:20 AM »
You've done a lot of good work there.  I suspect you haven't got much farther to get it fixed.
One point of info I like to have is if all the head pipes run about the same temp at idle and with the throttle set to run on the slide needles.
Also, are all the spark plugs showing the same deposit color and pattern.

The non-original carbs make me suspect non-original parts in the carbs you do have.
 The slide needles will have a number on them, that would be nice to know.
The jet are stamped with numbers, too.  And, it has been known to happen that they may have been drilled larger, which would invalidate the number marking.

It might be worthwhile the "prove" the air jet and carb body passageways are clear.

Is there soot collecting in the exhaust?

You comments make me question the float height setting or more importantly if the fuel level in the float chambers is correct.
You might run a clear tube up the side of the carb bowl from the drain port to verify that they are filling to about 2mm below the bowl mating flange.

If you don't find a smoking gun with the above, then run it for as long as you can stand, while at the throttle position where power is lost, then hit the kill switch, pull in the clutch and stop the bike.  Then pull out the spark plugs and "read" the combustion deposits on them.
One, they should all show the same. Two, they will show the mixture settings or combustion conditions at the time of the trouble.

Lastly, do not expect the stock carb settings for an F model to be accurate for a bike with a different, non-stock muffler.  Certainly #98 mains will not be correct.  The slide needle may even need a change too, depending on the back pressure change.

That should give you something to investigate.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline dave500

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #6 on: June 26, 2011, 12:56:29 AM »
main jet o rings suspect?oversize drilled jets?get the float height correct,remove the exhaust and try it,might have a blockage?

Offline classic bike tuner

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #7 on: June 26, 2011, 02:51:01 AM »
did you scheckt the advancer from the ignition 

Offline Jon

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #8 on: June 26, 2011, 04:00:33 AM »
+1 on checking the exhaust for restriction

Sounds like an air flow restriction;
When you ran it with no airfilter did you leave the airbox lid off as well?
Did you try turning the fuel tap off & keep riding to see if it picks up before it dies?
Tried pulling the choke on a bit when it starts to bog?


Cheers
jon

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BMW R90S

Offline Tintop

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #9 on: June 26, 2011, 04:11:34 AM »
main jet o rings suspect?oversize drilled jets?get the float height correct,remove the exhaust and try it,might have a blockage?

+1 TT  & Dave500 on making sure the float heights are correct.  Also removing the muffler to check back pressure.  A partly plugged, or collapsed baffle could cause those kind of symptoms.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline steam-powered man

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #10 on: June 26, 2011, 08:50:02 AM »
not sure about the fouled plugs, but could the stumble be caused by insufficient fuel delivery?  is the in-tank filter free of debris?  also, try running the bike with the fuel cap loose to rule out a clogged cap vent.  good luck.
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Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #11 on: June 26, 2011, 11:00:46 AM »
TwoTired:
Quote
The slide needles will have a number on them, that would be nice to know.

All of the slide needles were stamped 272304. All were clean and shiny with no damage.
All pilot jets were #40 and all mains were #100. I have a spare set of carbs (022A) that came with the bike, but they need a serious amount of tlc. I suppose I could pull the main jets off of those carbs and swap them to see if that makes a difference. They are marked #100 as well.

[/quote]One point of info I like to have is if all the head pipes run about the same temp at idle and with the throttle set to run on the slide needles[/quote]

My dad couldn't find his infrared thermometer gun, so I have nothing to test with but my hands. When the bike is cold and I start it, I can feel all the head pipes warming up at the same rate. After I stopped the bike to pull the plugs, I tapped each pipe with my hand three times quickly and all 4 pipes singed me equally (or so it seems.)

Quote
Is there soot collecting in the exhaust?

Yes there is, but the bike only smokes (black smoke, not blue) when it is revved into the 3-5k range.

Quote
Also, are all the spark plugs showing the same deposit color and pattern.

Yes they are. After riding it at 60mph at 5000rpm for about 5 minutes I shut off the bike and pulled the plugs. The ceramic is tan with a little soot and the electrode is white and clean. The deep recesses are covered in soot. The spark plugs were brand new before the test. When I had D8EA's they plugs were completely covered in soot. When I switched to D7EA, the soot largely went away.

Quote
It might be worthwhile the "prove" the air jet and carb body passageways are clear.

I haven't cleaned the emulsion tubes. Could that cause this sputtering? All other passages are verified clear.

dave500:
Quote
main jet o rings suspect?oversize drilled jets?get the float height correct,remove the exhaust and try it,might have a blockage?

All of the main jet O-rings are perfect. No swelling, hardening, or marring. All O-rings are fresh enough that main jets pop in and are held in place well. All leaf springs are present and working as they should.

I still need to figure out the float level thing. I have some clear vinyl tubing so I'll try TwoTired's trick with that.

If the jets are drilled oversize, I will replace them with the #100's in my spare set of 022A's.

I removed the muffler last night and drove the bike around. It lost low end power and didn't help the blubbering and inability to pass 5000rpm. The bike doesn't "cut out" electrically at 5000rpm it just gives all the symptoms of a rich condition. The engine doesn't seem to be knocking or pinging and the cylinder head seems relatively cool.

classic bike tuner:
Quote
did you scheckt the advancer from the ignition

Yes I did. That was covered in my first post.

Jon:
Quote
When you ran it with no airfilter did you leave the airbox lid off as well?
Did you try turning the fuel tap off & keep riding to see if it picks up before it dies?
Tried pulling the choke on a bit when it starts to bog?

Is the airbox lid that thing that snaps on the frame with the tool kit on top? I did remove that as well, but there is so much open space around the cover for air to pass through, do you really think it would make a big difference if I left it on?

I drove the bike in the regular petcock position and ran out of gas while i was accelerating. The bike bogged down and came to a halt. I switched the petcock to reserve, turned on the choke, and the bike fired up on one kick. I tried to get the bike to pass 5000rpm with float bowls that were barely filled to rule out overfilling, and the bike still bogged and stumbled.

If I turn on the choke a little bit, it makes the bike bog earlier in the RPM range. The more I turn on the choke, the earlier the bike bogs. Full choke will kill the engine when it's warm.

steam-powered man:
Quote
not sure about the fouled plugs, but could the stumble be caused by insufficient fuel delivery?  is the in-tank filter free of debris?  also, try running the bike with the fuel cap loose to rule out a clogged cap vent.  good luck.

I forgot to cover this in my first post, but I removed the fuel tank, emptied it of fuel, and splashed a full bottle of chemtool around in the tank for a while and then drained the tank. There were very little deposits that came out. The tank has almost zero rust. I also removed the petcock and disassembled and cleaned it. The screen is clean and undamaged. The petcock works as it should and doesn't leak in the off position.


Offline number13

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #12 on: June 26, 2011, 11:22:21 AM »
Wow, this is a real stumper, but...
Quote
The bike doesn't "cut out" electrically at 5000rpm it just gives all the symptoms of a rich condition.
...
could be caused by clogged emulsion tubes. The only thing I can think of at this point is a
completely wiped cam.
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Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #13 on: June 26, 2011, 11:40:14 AM »
I pulled two emulsion tubes while I was adjusting needle depth and they didn't even need cleaning. At that point I was so sure that adjusting the needles will solve my problem that I didn't even care to pull the other two. I was wrong  ::)

I don't understand how the bike could have a wiped cam at only 6700 miles. And it does only have 6700 original miles - the condition of the bike is like new, including the gauges which still have factory quality control paint that hasn't been disturbed.
I pulled all of the valve caps off and turned over the engine and all of the rockers pushed down far as they should. I adjusted the valves loosely to make sure I wasn't losing compression - that didn't help. I tried to do a compression test but my compression tester doesn't fit. So I slowly pushed on the kickstart through all of the individual compression strokes of all the cylinders and all "felt" equally hard to push. None seemed to give weak compression, but remember this is all by feel in the palm of my hand. I'm not getting any oil fouling or burning oil so I doubt I have shot rings. I should also add that I have adjusted the cam chain tensioner. No improvement.

Offline TwoTired

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #14 on: June 26, 2011, 12:13:08 PM »
At the speeds you are indicating trouble, the dominant fuel metering path is the jet needle.
So, do check the jet needle orifice for condition and size.  It is supposed to be 2.60mm.
Also check the emulsion tubes.  They should have two rows of holes, 5 in each row and they are sized 0.9 mm
Be certain the air jet passageway to the main emulsion tube chamber is clear.

If your undrilled #100 main jet is good.  Then to lean the midrange you would lower the slide needles.  With the stock air box/filter, the exhaust type would determine the carb tuning.  The MAC 4 into 1 with the standard baffle usually doesn't require a carb set up change for the 022A carbs.  The F model's 069a carbs would.

The CB500s lower displacement would suck less on the carbs than the larger displacement CB550.  So, it stands to reason that carbs set for lower displacement would run rich on a higher displacement engine.

I'd like to point out that true F models don't have the tool tray over the air filter that the K models do. Also, if you look at the bottom of the tool tray, you will see that it fits over the filter chamber pretty tightly.  There is supposed to be a rubber formed part that toward the front, so all the air ingress flows through the opening in the tool tray.  Perhaps you are missing this rubber part.  It is very unlikely this it significant to your current issues.  I just thought you'd like to know.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Popeye: "Wrong is wrong, even when it helps ya."

Offline Tintop

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #15 on: June 26, 2011, 12:21:10 PM »
This keeps sounding more a more like an over rich condition,...... That's how I started this post, but you have already added that you have checked the tubes, and you still have the issue.

So, a quick recap: the air box & filter have been checked and are OK (not restricting); the muffler is not causing excessive back pressure; and you are now certain that the carbs are clean & 100% to spec.  The only other item in the fuel delivery system that could cause the richness, would be the choke butterflies not fully opening.  If those are OK, it would seem the issue is not fuel.  The only other source to look back into, has to be the ignition.

From what you have previously done, it sounds like everything at the points plate has been covered (cleaned, dynamically timed).  I'll throw this out to TT, and those with more electrical knowledge - could the issue be borderline coils, or high resistance / poor connection in the wires / plug caps.?  ACVWguy mentioned that it would spin up fine with no load, but under load looses power, starting in the mid range.  The point where the engine is at full advance, and in the meat of the torque band, ie. max load.

Read you last post TT, and agree that the needle jets can become worn, but would think with only 6K+ this shouldn't be an issue.  However these aren't the original carbs so.... ???
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline TwoTired

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #16 on: June 26, 2011, 12:39:07 PM »
Read you last post TT, and agree that the needle jets can become worn, but would think with only 6K+ this shouldn't be an issue.  However these aren't the original carbs so.... ???
Actually, I haven't seen the CB500 or Cb550 Carbs wear the needle jets, or the needles.  They don't normally have any contact with each other.
But, they aren't the original carbs, and if they were they would be dirty by now.  So, I assume they were cleaned, and the emulsion tubes can be stuck pretty well in the carb bodies.  Since they are driven out from the jet orifice end, there is opportunity for them to be damaged there.  And, that is why they are worth checking.

You ignition point is well taken, though.  It is possible for the condensers to be out of spec. and cause marginal spark at higher RPMs.  Odd that they would both fail in such a way at exactly the same time.  But, it is possible for random events to coincide.
It doesn't seem congruent with having all clean plugs while the problem is present, though.

Cheers,
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Popeye: "Wrong is wrong, even when it helps ya."

Offline dave500

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #17 on: June 26, 2011, 12:48:10 PM »
the floats are in the correct way up?double check the float heights.

Offline Jon

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #18 on: June 26, 2011, 01:22:02 PM »
Try running a hot wire to the + of your coils & closing the gap of your points down to make sure the coils are being fully saturated.

Cheers
jon
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Offline WarwickE36

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #19 on: June 26, 2011, 01:37:09 PM »
+1 for float height... 22mm
" Why does anyone get offended by what someone does to their own bike? I dont get it. "

You made me think about it after I cheered knowing someone else would like to know what these control freaks are up to.
 Every time any owner strips whatever precious Honda part the horrified purists parts go up in value. That's not the part that bothers them.
 What bothers them is they sat up late at night, their breast full of wonder and estrogen, unable to sleep, dreaming about their lovely darling and all her glory... and next thing you know someone else doesn't share their emotional deluge and their reaction is they must spread their mind museum as far as they possibly can, taking over as much of the real world as possible.

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Offline Tintop

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #20 on: June 26, 2011, 03:46:07 PM »
Read you last post TT, and agree that the needle jets can become worn, but would think with only 6K+ this shouldn't be an issue.  However these aren't the original carbs so.... ???
Actually, I haven't seen the CB500 or Cb550 Carbs wear the needle jets, or the needles.  They don't normally have any contact with each other.
But, they aren't the original carbs, and if they were they would be dirty by now.  So, I assume they were cleaned, and the emulsion tubes can be stuck pretty well in the carb bodies.  Since they are driven out from the jet orifice end, there is opportunity for them to be damaged there.  And, that is why they are worth checking.

You ignition point is well taken, though.  It is possible for the condensers to be out of spec. and cause marginal spark at higher RPMs.  Odd that they would both fail in such a way at exactly the same time.  But, it is possible for random events to coincide.
It doesn't seem congruent with having all clean plugs while the problem is present, though.

Cheers,

Agreed TT, if the brass needle jets were removed using a hard object (punch?) versus say wooden dowel, they could easily get damaged.  Probably the only thing not check at this point to see if it is in spec.

Also agreed that it seems odd that there would be an across the board failure.  The OP did mention that there was some carbon build up, although the new plugs used appeared otherwise OK.  It may be that the OK part was from the lower rpm area were it is OK, and the build up started when he reached the problem rpm area.  He does also say that this is when the black smoke (unburned fuel) starts.  Maybe if he had continued longer, before doing the chop, the build up would have been greater.  I'm thinking here of bwaller's issues were his race bike, which would not rev past 9K.  It had all the symptoms of over rich, or a bad rev limiter, but turn out to be coils which could not support an effective spark at or past that point.
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #21 on: June 26, 2011, 04:55:58 PM »
Alright I made a breakthrough! I think.

Everybody loves pictures so...



I decided it would be a good idea to check one of the main jets on my bike with one of the main jets in the spare 022A set that came with the bike.

Both jets are marked #100. The one on the left is the spare from the 022A and the one on the right is out of my bike. As you can see from the pic, the orifice is significantly bigger on the one from my bike (right).

Because, during the needles operation, it uses the main jet as a passage for fuel(?), would this cause my stumbling from 5000rpm to WOT?

Offline TwoTired

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #22 on: June 26, 2011, 05:13:04 PM »
I don't see any pictures.  But, if the main has been drilled oversize, it surely can flood the mixture above half throttle position.
Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Popeye: "Wrong is wrong, even when it helps ya."

Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #23 on: June 26, 2011, 05:19:11 PM »
does this link work?

http://by151w.bay151.mail.live.com/att/GetAttachment.aspx?tnail=0&messageId=1fc73978-a04f-11e0-a71a-001e0bccc9ae&Aux=14|0|8CE027307338490||0|0|0|0||&maxwidth=220&maxheight=160&size=Att

Offline ACVWguy

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Re: 1975 CB550F Lacks power! HELP I AM DESPERATE!!
« Reply #24 on: June 26, 2011, 05:20:24 PM »
Nevermind. I don't have an image host I just uploaded to my email.

Well my jet in my bike is significantly larger than the jet that I removed from my spare carbs. They are both marked #100

 

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Honda