Topic: 1977 CB550 Roll On Acceleration - Have questions, need advice

[rsank]

Hi Folks,

Thanks to everyone who helped me on this forum. I have finally completed all 3k tune up items on my 1977 CB550F. I was waiting on my  vacuum sync kit to arrive in the mail, I had done all the other stuff earlier. I have a Uni foam filter in the original air-box, everything else is stock, idle screws are out 1 1/2 turns from seated position. Points are old but the gaps and ok and timing also is fine (static check).

I had issues with one cylinder running rich and it turned out to be the float in the carburetor being set too high. I reset that and fixed the issue. I put in a nice set of Progressive shocks and springs and it handles beautifully now.

The bike runs well and will do highway speeds just fine. I have not taken it over 80mph yet.

Now that I am using it more like a regular bike, I am starting to compare it with my 2010 Honda CBF 600. I know it's apples and oranges but since I have never ridden a bike this old (I was only a little kid when it came out) with no accelerator pump I need you guys to tell me if this is normal.

From a stop, I notice it doesn't immediately shoot off like my fuel injected or even my older carbureted bikes do. I have to let the clutch out slowly and make the revs build up before it will get into it. It will still out accelerate most cars from a stop light but it has that initial thing where it needs to be built up before it will take off. If I give it a couple of revs to 2000rpm or so, it seems to move faster from a stop but not from my 1000 rpm idle. Is this to be expected?

Also, the other day I was riding up a fairly steep hill. On third gear I was doing about 4500 rpm at 45mph or so but rolling on the throttle to nearly wide open, topped me out to 5000rpm and no surge in power. I had to gear down to 2nd, get the revs up to 5500-6000rpm and then shift to third to get it going to 55mph and over. On my other bike (I can't remember how it was with the older ones), even up that hill, I just have to roll the throttle and we are off to the races.

Also, I have noticed that I had to use wide open throttle to get it really moving with acceleration that I am used to on my modern bike. I am not used to using wide open throttle because on all the bikes I have owned in the last decade or more, that would get me in big trouble. I am getting myself used to really giving a fistful of throttle with the CB550.

Any words of advice? Is this consistent with your experience or do I still need some work on my bike to get it running well?

Thanks!

[flybox1]

your air fuel mixture is off.
we need to know what jets, and needle clip position you are running in your carbs, and a peek at the color of your plug insulators will give us more information.

[rsank]

Thanks flybox1.

I will do the easy stuff first and post up a picture of the plugs. I did examine them and apart from #1 (for which I reset the float level), they have the tan color. #1 is more blackish because it was running rich before and I was just cleaning out and putting it back in.

Do you suggest I put new plugs and run tests with that? I had that chronic rich condition and I was cleaning off the plugs regularly before I finally addressed it.

[flybox1]

new plugs are best, unless you can soda blast your existing ones clean.
if you take your uni filter out of the airbox, does your bike run better?

[strynboen]

yes you are running lean at even at some rpm..maybe not the hole rpm areia..be care it melts the pistons over time..or the ignision advanser is Loose or/stuck at low..this bikes have a nice almost liniar power autput..better then most dohc or 4 valve p.c.. engines..so somthing are not 100% korrekt tunet..is all rubber tubes nev and teight..so it not takes air inn..

and all flybox says too..

.are the tank total klean..dirt/rust make a total mess..even it not can bee seen ..and inline fuel filters make more mess then good..so get rid of them. they.mess up the fuel flow

[rsank]

Okay! I will put a new set of plugs in today.

Will try taking the filter out and see how it runs. Also will leave the filter in and try running it choked a little and see if that will make a difference.

Now one thing to note, there is no popping on deceleration and also after a 60 mile ride, the engine fins are not so hot that I can't touch them. I can't put my hand on them for more than half a second but they are not so hot that I can't touch'em.

Thanks guys! I will post back the results. It's rainy today so I will take the bike out tomorrow for a long ride and post a photo of the plugs.

After that we will open up the carburetor.

[rsank]

yes you are running lean at even at some rpm..maybe not the hole rpm areia..be care it melts the pistons over time..or the ignision advanser is Loose or/stuck at low..this bikes have a nice almost liniar power autput..better then most dohc or 4 valve p.c.. engines..so somthing are not 100% korrekt tunet..is all rubber tubes nev and teight..so it not takes air inn..

and all flybox says too..

.are the tank total klean..dirt/rust make a total mess..even it not can bee seen ..and inline fuel filters make more mess then good..so get rid of them. they.mess up the fuel flow

Yes, and the rubber boots are all good but I will go and check them again.
The tank is good and clean as far as I can tell. I do have an inline filter though! Okay, time to lose the filter and try with that.

[strynboen]

you can/vill, smell the burned oil at the finns if the engine get over hot...so that is probly not the problem..

a 77 engine have all valve shaft updates..as 500 f, fights vith..and the new type kaburettors.. air mix 1-1/2 rotating open from closed is korrekt..

try to thek the battery voltage..it gives veak ignision if the voltage is low

[rsank]

Thanks strynboen! No smell of burning oil for sure.

The battery is fine, a little bit discharged, voltage 12.2-12.3. I have a voltmeter plugged in an accessory socket (twotired had given me that tip last year) so I can monitor the charging and voltage while riding. Charging system is alright.
But I am still running the accel coils. I have not replaced them yet with the 4 ohm coils.

[strynboen]

try the fuel vay first..and make a drain test..to be shure it flows,,,from the(fuel) tap in more minuts or more time..vaccum in the tank..is just one more to thek...for...miee starve vhem i ride full speed for long time..think i have a vaccum problem..but only at heighvay riding long time full speed..not your type problem

[rsank]

Yes! Thanks so much.

I have a few things to try out. Definitely removing the fuel filter, I just checked it and it is not looking very clean ... ;-)
The fuel seems to be flowing out of the tank fine. A few days ago when I was doing the vacuum sync, I let out some fuel from the tank to fill my bottle. But that was directly from the tank and not from the inline filter.

I will try all the tests and report back in a couple of days.

[strynboen]

fine rust goes through the filter.. .thats vhy i dropped it..and accic kleaned mu tank instead..and then the bike have runn since 2-3 years now..before that i hade some month full of problems

[rsank]

Yeah that might be what happened to me last year when I first bought the bike. It was not used for a long time and when I started riding it, in just a few days, one of the float needles got stuck and causing one carb to overflow. I am hoping that after almost 1100 miles of riding, most of the junk is now gone.
But we will see ... :-)

[rsank]

I am a complete idiot. Don't know how I missed something so obvious. There were signs but since the bike was idling well I assumed all was well. The bike was running on three cylinders after my so-called float height reset on carb #1. The floats were drooping and I have an aftermarket main jet clip. It looks like it was forcing the float up and closing off the gas.
I dropped the bowl and straightened the clip and the floats. But I don't trust myself anymore. I am going to do the clear tube test.

Anyway, I rode the bike and it is flying. Went for a 10 mile ride, and here is the picture of the plugs.

Please advise.


Sent from my iPad using Tapatalk

[flybox1]

all are lean, but #2 is just starting to show good color...

[flybox1]

#2 is probably better from a slightly higher fuel level in the bowl.
....and you still haven't told us what main/pilot jets/needle clip position you have 

[rsank]

Thanks! So just to recap, I bought the bike last year. I have messed with carbs #1 and #2 but I haven't touched #3 and #4.
Yesterday, I removed the inline fuel filter as well.

I have two questions.

1. I have been checking/setting float height with the carburetor installed. I have not taken it out. So I have had trouble measuring it because gravity tries to pull down that float needle. It slips down and it's hard to tell when exactly is it seated, because the tang of the float will touch it always since it is sliding down in its seat. Do you know what I mean? It is so tiny that with everything in place, it's really hard to use a pin or something to push that needle up to where it seats and then measure the float height. To really set the height accurately, it needs to be on its side so there is no gravity pulling down on that float needle. Am I missing something here? Is something wrong with my float needle?

2. If I drop the bowls, the main jet can just be pulled out? The pilot jet, unscrewed? And I have to remove the top and diaphragm to get at the clip needle. Can all this be done with the carbs installed?

Thanks for your help!

[harisuluv]

I have two questions.

1. I have been checking/setting float height with the carburetor installed. I have not taken it out. So I have had trouble measuring it because gravity tries to pull down that float needle. It slips down and it's hard to tell when exactly is it seated, because the tang of the float will touch it always since it is sliding down in its seat. Do you know what I mean? It is so tiny that with everything in place, it's really hard to use a pin or something to push that needle up to where it seats and then measure the float height. To really set the height accurately, it needs to be on its side so there is no gravity pulling down on that float needle. Am I missing something here? Is something wrong with my float needle?

2. If I drop the bowls, the main jet can just be pulled out? The pilot jet, unscrewed? And I have to remove the top and diaphragm to get at the clip needle. Can all this be done with the carbs installed?

1.  You don't check it with the float's weight affecting the height.  As you alluded to, hold it at the side to where it just touches but doesn't depress the spring plunger.

2.  No.  No.  No, and yes.

The main jet is unscrewed.  The idle jet is pressed in (pulled out).  There is no diphragm.  Yes, you need to remove the cap in order to access the slide assy.

What you said is true if you have pre 77 carbs (NOT pd carbs).  But I will assume you have the carbs for the bike listed.

With all due respect, If I were you, I would really do a lot of reading and researching before you do much more.  It seems like you need to educate yourself a bit before diving in.  A search on any of these topics probably has numerous threads and I would start there.  Familiarize yourself with your carbs before you jump in.

[flybox1]

Take your carbs off the bike.
Familiarize yourself with them on a table. 
Its much easier, and less cramped for you, trying to do all this stuff.
It'll also be a good time for you to go thru them properly, check and clean.
Do it once, do it well.  Take pictures and post them here if you have a question.

[rsank]

Alright guys thanks very much!

Harisuluv, I am a complete noob! I didn't want to take the carbs out for precisely that reason. Didn't want to get over my head and make a bigger mess than what I already have. So whatever checking I was doing was with carbs on the bike. This is a 1977 CB550F super sport so as far as I know it doesn't have PD carbs. Correct?

Since I know nothing about the history of this bike and what has been done to the carbs (it does appear that some kind of rebuild was done by some previous owner), it is probably time to take them out of the bike and study them

I am also considering sending it over to you and having it done right. Apart from these carburetors the bike is fine, really.

[Stev-o]

 This is a 1977 CB550F super sport so as far as I know it doesn't have PD carbs.

I dont think so, either. My '76 550F has 069A carbs. 
Look on the right side of carb #4, it is stamped on the carb body.

[harisuluv]

oh ok, i was looking at the picture someone posted and thought that was you op.  I can't stress enough how much pictures help you, help people help you.  Help answer questions with just a look.

[rsank]

Yes, it is a 069A.

Sorry, I should have mentioned that.