Topic: CB550F carbs on CB500

[turboed13b]

#115 are still huge and each jet manufacture are different so it is really a shot in the dark at guessing jet sizes. I would stick to stock jet sizes in (40 and 100) and start  going up on mains only if needed. For example if you can only ride with a little choke then go to #105 there is no need to jump all the way up to #120.

[Matte Black]

#115 are still huge and each jet manufacture are different so it is really a shot in the dark at guessing jet sizes. I would stick to stock jet sizes in (40 and 100) and start  going up on mains only if needed. For example if you can only ride with a little choke then go to #105 there is no need to jump all the way up to #120.

I did exactly that...
(Added 4 into 1 exhaust / open headers & Pod filters)
#100 > #110 > #115 > #120 < #115
#40  > #42  <  #40 < #38
2nd groove > 3rd groove

Should I move the needle clips again? Maybe to 4?

[turboed13b]

Were you finding lean conditions on lower jets or just going up higher because there was no change? My fleet of about 10 cb550/500 all have #110 and lower mains. Running open exhaust and pods on most of them. The needle has most influence on mid range but you should be finding the correct main before moving on.

[Matte Black]

Were you finding lean conditions on lower jets or just going up higher because there was no change? My fleet of about 10 cb550/500 all have #110 and lower mains. Running open exhaust and pods on most of them. The needle has most influence on mid range but you should be finding the correct main before moving on.

Well every time I went up, it had more power, but mostly because of hesitations. Maybe also because of loud sucking sounds. The most power/responsive it's been IMO was #40/#120, but what do I know, I'm a "novice".

Also, I just thought to mention, but since I went down to #38, it shakes a bit at idle. The engine's never shook before.

Do you have a 500 with pods & 4-1 & open headers? Could you please tell me it's jets and needle clip groove position?? I'm assuming #40/#110/4th?

[turboed13b]

I have a few but they are all different.

1st: #40 #100 (2nd from top running cb550 carbs)
2nd: #40 #105 ( 3rd from top a little rich in mid 2nd from top may be better)
3rd: #40 #105 (2nd from top)

If I remember right I only have one cb550 running #110 and  I have successfully done "the ton" on it.

[Matte Black]

I have a few but they are all different.

1st: #40 #100 (2nd from top running cb550 carbs)
2nd: #40 #105 ( 3rd from top a little rich in mid 2nd from top may be better)
3rd: #40 #105 (2nd from top)

If I remember right I only have one cb550 running #110 and  I have successfully done "the ton" on it.

Thanks! Do these all have pod filters and 4 into 1 open exhaust?

[turboed13b]

I have a few but they are all different.

1st: #40 #100 (2nd from top running cb550 carbs)
2nd: #40 #105 ( 3rd from top a little rich in mid 2nd from top may be better)
3rd: #40 #105 (2nd from top)

If I remember right I only have one cb550 running #110 and  I have successfully done "the ton" on it.

Thanks! Do these all have pod filters and 4 into 1 open exhaust?

Some have open headers that end at the footpeg and one has a mac exhaust without baffle. All are using cheap emgo filters besides one which is using uni foams. I use these jets also http://4into1.com/replica-keihin-press-fit-secondary-main-jets/

[Matte Black]

Some have open headers that end at the footpeg and one has a mac exhaust without baffle. All are using cheap emgo filters besides one which is using uni foams. I use these jets also http://4into1.com/replica-keihin-press-fit-secondary-main-jets/

I have the cheap Emgos (Had Uni foams), those exact mains from 4into1.com, and Yoshi-style 4/1s without baffles. Obviously it's not a universal thing, but being you've built so many 500/550s with similar mods, on my 500 with 550 carbs, would you suggest I start at #40/#110/2ndFromTop and go from there? I agree I may need a clean start, I'm all over the place.

Thanks again.

BTW, were you suggesting I should be adjusting pilot/air screws when I vacuum sync? Or were you asking if I do it?

[Matte Black]

OK, took a leap of faith and matched some of @turboed13b configurations, kinda, and I'm happy to say that for the first time, she had NO DEADSPOTS, whatsoever! The setup I did was #40/#110/2nd and other than one new issue, and the same issue with degrading when it gets hotter. I think the leaner conditions are making it take longer to heat up, and it's not getting as hot as it used to. That's great.

The new issue is that she now hangs for a few seconds before dropping back to idle rpms. This hanging issue is very sensitive to what I have the idle knob at. Literally a 1/16th turn and it will hang nonstop.

What should I go to next? I def want to keep the needle clips at 2nd, which I believe was the cause of the dead spot when at groove 4. And the slow jets I think are fine at #40. Should I change the mains to a bigger or smaller size? I actually have #105 and all larger sizes up to #120.

Other ideas:

Could the lack of back pressure of the baffle-less exhaust cause the delay to idle?

I just re-built the points and the timing advance isn't sticking, I think that could be ruled out.

My mech suggested a smaller needle jets as he thought perhaps air was getting passed the needle, hanging it up. He also said that was a just a shot in the dark.

Note: I need to reset the timeing chain tentioner, I'm getting a chain rattle. Doubt that could have anything to do with anything, but thought I should mention.

Finally, I didn't have time to vacuums sync this time. I can do that and report back if that's recommended, before changing anything else.

[BomberMann650]

Vacuum sync will probably solve your return to idle issue.

[Matte Black]

Vacuum sync will probably solve your return to idle issue.

I re-synced em and the idle issue improved about 50%. A bit of an improvement, but maybe my syncing skills aren't the best because adjusting wasn't very stable and took me over an hour.

The new issue now is its lags a little in acceleration, and I feel a bit of a power loss throughout.

I'm not sure where to go from here. I have a feeling I should go higher than the 110 mains, but y'all keeps saying that would be too big...

[DaveBarbier]

What's your float height? Ever clear tube these carbs?

[Matte Black]

What's your float height? Ever clear tube these carbs?

Tube test won't work with these carbs. The drain tube and drain valve aren't connected, so when I loosen the valve it just drains out of the screw not the tube.

I've always wondered if I could just drain into an extra bowl. I have an extra set of 627B bowls in a box somewhere I can use to determine the amount of fuel milks into it. I'm assuming they are the same size bowls at the 069A, since all require a 22mm float height.

I havent checked with calipers either, ive always just eyed em tilting it on an angle. All looked fine, with nice n springy new needle valves.

I'd love to rule out float heights as an issue. I'll try the "extra bowl" test unless someone thinks that's a dumb idea.

[DaveBarbier]

Tube test won't work with these carbs.

Lies! Sure it will! Most carbs don't act like PD carbs where they drain from the overflow nipple when you crack the drain screw. With the bowls empty, unscrew the drain screw and jam in some fuel line, it'll work just fine. You can even heat the tube (away from where fuel is obviously) with a lighter and it'll form on the threads better.

I would clear tube them first to see where you're at. If they're way off, it would be nice to know.

Shoot for 4mm from the bowl seam. Try to get them as exact as you can so you know that it's right. If you want to be a pro, clear tube them on the bench. Make a little stand or something. Beats taking the carbs off and on.

I havent checked with calipers either, ive always just eyed em tilting it on an angle. All looked fine, with nice n springy new needle valves.

Duuuude, you're killin' me! You can't eyeball floats.

Are the needles valves new OEM or aftermarket? Because with aftermarket you'll likely not use the stock float height spec. Sometimes the needle is longer or the plunger in the needle is taller or shorter than stock throwing the stock spec out the window.

I'll try the "extra bowl" test unless someone thinks that's a dumb idea.

I do

Seriously though, float height is a basic thing. I'm not saying it'll fix your issues but you can't expect the carbs to perform well if they're not properly setup.

[Matte Black]

Lies! Sure it will! Most carbs don't act like PD carbs where they drain from the overflow nipple when you crack the drain screw. With the bowls empty, unscrew the drain screw and jam in some fuel line, it'll work just fine. You can even heat the tube (away from where fuel is obviously) with a lighter and it'll form on the threads better.

I'm confused. I loosen the drain screw, and gas only comes out of the screw's port.

I found this which looks like it's the solution for the drain valve clear tube test:

[DaveBarbier]

Lies! Sure it will! Most carbs don't act like PD carbs where they drain from the overflow nipple when you crack the drain screw. With the bowls empty, unscrew the drain screw and jam in some fuel line, it'll work just fine. You can even heat the tube (away from where fuel is obviously) with a lighter and it'll form on the threads better.

I'm confused. I loosen the drain screw, and gas only comes out of the screw's port.

I found this which looks like it's the solution for the drain valve clear tube test:

Drain the bowl of gas. Remove the drain screw completely. Shove some fuel line in the drain screw's hole and twist to have it grip the threads. Turn on the petcock (might have to tap on the bowls a bit with a screw driver handle to keep the float from sticking in the down position) then read the results. Snap a picture if you can too. Do this for each carb.

If you only have larger fuel hose, heat it up and stretch it. As you pull it'll thin out and make it easier to fit in the hole.

And yeah, you can get another drain screw, drill it and solder or epoxy a nipple on it like in the picture, but shoving a tube in is faster and works just as well, albeit a less graceful solution.

Edit: That picture says 3mm. I think 3 or 4 would be ok but make sure they're all the same.

[Matte Black]

Shove some fuel line in the drain screw's hole and twist to have it grip the threads

Oh, it's like that hu? In that case I will try although I measured my extra drain valve and the threads are 6mm x 0.75, and since I need to buy the fuel line I might as well try and find a fitting.

Thanks for the idea, I've fowled #3 yesterday so I have a hunch fuel level could be an issue.

I'll be back with some pics.

[Matte Black]

Snap a picture if you can too. Do this for each carb.

I checked the mm and pitch of my drain screws, and stumbled upon a tool for Kawasaki and Suzuki taht happened to have the exact same size drain port. Great quality, and fit perfectly: https://www.z1enterprises.com/product/ZSM01-208 Ironically, included were instructions that happen to be the exact same image I posted above. Hah.

Anyways, I bought two and checked each side individually... Here are the photos below. The first two are #1 & #2, the last three are #3 & #4. #1 & #2 are super high, no??

(Since these were shot with my iPhone, they are sideways on the thumbnails. Its not the case on the full size images)

[DaveBarbier]

Nice, seems like you're getting somewhere. Good that your levels are out of whack. 1&2 are too high and 3&4 are too low. I assume the bike is level...i.e. not on the side stand?

Get all to be 4mm below the bowl seam (where the bowl meets the body) and see if problems persist.

Just so you know, with the levels as they are 1&2 will run rich and 3&4 will run lean. That could throw things off quite a bit. My little CL200 had a weird hesitation at 1/8th throttle and I cured it by raising the float height (lowering the fuel level) by 2mm.

[DaveBarbier]

Another thought: Since you've been changing jets, IMS and needle settings with the the fuel levels out of whack, you might not see any positive change with just setting the fuel height correctly. If others are still following this post I would recommend a test ride after changing fuel height. Then if problems still persist, I would go back to more "normal" jetting for pods and a 4-1.

Post some pictures of your bike please. I'd like to see the exhaust and such.

And, just to confirm your current issue; you're experiencing a hesitation at around 1/8th throttle when the bike warms up. Correct? Before it warms up, no issues. Correct?

Also, read up on plug chops. They are in your near future if you've still got issues.

[Matte Black]

Another thought: Since you've been changing jets, IMS and needle settings with the the fuel levels out of whack, you might not see any positive change with just setting the fuel height correctly. If others are still following this post I would recommend a test ride after changing fuel height. Then if problems still persist, I would go back to more "normal" jetting for pods and a 4-1.

I will be adjusting the fuel heights. Glad you suggested testing them, will take care of it.

The conditions are changing a lot while I continue to re-jet. Let me clarify conditions, and luckily with the temperature changing outside recently a few more conditions may be apparent for our forensics.

Within he last few posts here I've done a few changes in leu of a severe dead spot  around 1/8 OT. Hanging idle. No issues with starting without the need for choke.

I moved the needle clips to 2nd groove from the 4th and shrunk to mains to #110 from #120. Air screws at 2 out.

Current conditions are as follows:

Difficult to start. It's kind-of cold out btw. Need to choke to start. Once starts, runs rough while warms up. After continuous adjusting the curb idle screw I get a nice idle after a few minutes.

Once riding, I need to continuously lower the curb idle screw to get a good response without hanging RPMs. Slightly high idle setting cause RPMs to hang and I can't get yo idle unless I drop idle screw down to a proper sped.

The worst part is the high end power loss. The majority of the power is from 0-1/3 OT and really dies out once I open the throttle. Depressing. Prior to dropping mains to #110 the high end was strong and weak on the low end. I have no high-end power, feels like she's starving.

On the bright side since the latest changes I've made, I don't really have any dead spots anymore. I believe it's due to moving the needles down based on turboed13b examples. That really pleases me, there's nothing I hate more. Even though she's super weak.

The exhaust is a baffel-less yosh-like stainless setup I recently added. See pics.

I know plug chops. I have 3 other CBs I've been able to dial in. This one is not at that point yet...

Thanks!

[turboed13b]

The idle hangs when the slides are open too far because there isn't enough vacuum to pull fuel through and it causes a lean condition. Once the slides are lowered more vacuum is created and more  fuel is then pulled in. Once you get the bike fully warm it should idle at 1000 rpm. Leave it there and don't touch it these bikes  run crappy when cold and will need some throttle holding until it can keep its own idle.

What is your timing like? One of my bikes suddenly started feeling really weak and eventually started to die on long rides. Somehow my timing became 10° retarded  and it made my bike feel like something was seriously wrong I went so far as changing jets and needle heights but it was just the timing. Also make sure your advance is working properly.

[DaveBarbier]

Turboed is right, the idle knob isn't something that's supposed to be adjusted often. It's a set and forget. Your carbs might have a fast idle cam. Between #2 & #3 carbs look for a screw with a spring that probably has some yellow paint on it. That's so when the choke is pulled, it raises the slides a hair. It's nice to have one. I'd say you can adjust it later once you fix all your issues. But in lieu of that, just cracking the throttle with your hand for a bit is better than fiddling with the idle knob.

It's normal to use the choke whenever the engine is at ambient temperature, it's not only for when it's actually cold out. Even in the summer when it's 90° I need choke to start if the engine is at ambient temp. And the bike will run rough when the choke is on, that's normal.

Set the fuel heights and take it for a spin. The plug chops are not just for minor tweaks. They can help you with larger moves too. After you take it for a spin and sense where your bike is after the float levels are proper, you'll start with a plug chop at WOT. Really giving it the beans for as long as you can...multiple minutes. Read the plugs and it'll tell you what to do.

Nice bike!

Regarding turboed's comment on timing, I've just assumed (maybe wrongly) that the full 3k mile service has been completed. Tappets, cam chain, point gap and timing, etc. If not, stop everything and do that in the order that's in the FSM.

How about some more pictures? Some close ups of the carbs would be nice.

[DaveBarbier]

Also, just saw that you're in Manhattan. I'm in southern CT about an hour and a half out. We should ride some time

[Matte Black]

The idle hangs when the slides are open too far because there isn't enough vacuum to pull fuel through and it causes a lean condition. Once the slides are lowered more vacuum is created and more  fuel is then pulled in. Once you get the bike fully warm it should idle at 1000 rpm. Leave it there and don't touch it these bikes  run crappy when cold and will need some throttle holding until it can keep its own idle.

Yeah, I've always heard this is the way it is on CB's, but out of all my CBs this is the only one that won't idle right during warm up. Are all of your 500/550s like this? Is this really a 500/550 thing?

What is your timing like? One of my bikes suddenly started feeling really weak and eventually started to die on long rides. Somehow my timing became 10° retarded  and it made my bike feel like something was seriously wrong I went so far as changing jets and needle heights but it was just the timing. Also make sure your advance is working properly.

Other than carbs, setting my timing and checking my advance was the last thing I did. The timing was a bit off, I adjusted it, and the advance wasn't sticking. Perhaps I'll take another look again, its been like 6 months and she's been my daily.

The next thing I'm doing is adjust my fuel levels. And since I'll have the bowls off, I'd like to do another jet swap. Currently I'm using #110s and since I'm currently experiencing a bad power loss on the high end, I'm contemplating going back up to #115s, while the needle clips are at 2nd groove. It's totally bogging down at WOT. It didn't do that when I was running bigger mains. Thoughts?

It's normal to use the choke whenever the engine is at ambient temperature, it's not only for when it's actually cold out. Even in the summer when it's 90° I need choke to start if the engine is at ambient temp. And the bike will run rough when the choke is on, that's normal.

Yeah, before I made the changes I didn't need a choke at all. Now I do only until it starts running, which I was mentioning it as progress.

Set the fuel heights and take it for a spin. The plug chops are not just for minor tweaks. They can help you with larger moves too. After you take it for a spin and sense where your bike is after the float levels are proper, you'll start with a plug chop at WOT. Really giving it the beans for as long as you can...multiple minutes. Read the plugs and it'll tell you what to do.

Nice bike!

Regarding turboed's comment on timing, I've just assumed (maybe wrongly) that the full 3k mile service has been completed. Tappets, cam chain, point gap and timing, etc. If not, stop everything and do that in the order that's in the FSM.

How about some more pictures? Some close ups of the carbs would be nice.

Priority is to set the fuel heights. Going to do another tube test on the bench. I can't wait to read the plugs, at the moment it doesn't idle well and I can't even get it to WOT either.

I've serviced everything u mentioned, I do need to auto-adjust the cam chain tension-er though, I can hear it's a tad loose. It's on the list of my other issues I'm sparing y'all on. Oil pan leak, can't move to neutral, replace rear shocks, squeeeeeling front brake, etc. etc.

I'll pop up some more photos soon! Since this is a thread about my 069A, below is a glamor shot!

Also, just saw that you're in Manhattan. I'm in southern CT about an hour and a half out. We should ride some time

Totally, always down for a ride! I bet CT has better moto-roads than NYC...