Topic: new project 77 CB550

[mitch5069]

I'm new to this message board and I would like to thank everyone ahead of time for the help. I recently sold my CM250 to fund a 1977 CB550 project but am having some trouble starting out and could use some advice.

I picked the bike up about two weeks ago and rode it home (2miles). The bike started with a couple kicks but would only stay running with the choke on, also it would rev high after letting off the throttle and then come down in rpms (I assumed this is some type of air leak on the carb boots). I started digging into the area around the carbs (i have only worked on the CV style carbs not the type that are on this bike) and noticed that several of the boots coming out of the blower box only had zip ties sealing them and were ripped/cracked. I eventually was going to go to pods and since I would have just as much money in the new boots I decided to pick up some UNI filters and I have larger main jets on the way. Since I am impatient I tried to start it today. The bike starts fine now but still will only run with either the choke partially on or the idle set high. When I let the clutch out to take off the bike seems to have no power and will only start going if I really give it some throttle and even then it is sketchy.

What is everyone's thoughts on the next steps? I have all stock jets (well stock to me when I got it) and the idle screws out 2 turns. I only remember the main jet size when I pulled them apart and they were 90s so I ordered some 100 to compensate for the uni filters. Also the exhaust is a 4 to 1. Do I need to adjust the idle screws out a bit further? I read people online talking about some type of clip setting on the needle? I am not familiar with this.

Thanks a ton,
Mitch

[Bankerdanny]

CB550K or CB550F? If you aren't sure check the tag on the right side of the steering neck. The difference is important. The '77k and the '77F have different carbs and the connectors between the air plenum and the carbs are also different. The carb gaskets are also different, so you need to know what you have to order the right carb kits.

The F also has a 4-1 from the factory. The OEM exhaust is immediately identifiable because all 4 tube sweep to the left of the oil filter housing as you are looking at the engine (or to the right when seated on it).

The air plenum to carb connector boots should have regular hose clamps on them.

I appreciate your desire to ride, but you will never get it to run right with major leaks either before or after the carbs.

When asking questions pictures of your bike go a long way to helping us help you. As a new member your ability to post pictures will be limited for the first few posts. Using a picture hosting site like Photobucket can help.

[mitch5069]

Bankerdanny:
I am 95% positive it is the K model but can confirm later today. I will post a photo below of the bike but it is only a side shot not sure if you can tell on the exhaust from that. I would like to be clear that I assumed there was a vacuum leak but did not confirm that. After putting the pod filters on I checked the engine side of the carbs by spraying carb cleaner around the boots and then did it with propane and the idle did not change. Based on that I am assuming the engine side boots do not have leaks, what are your thoughts?

calj737:
If the clutch is slipping would the RPMs still drop when I let out the clutch? I had a similar issue with 79 cb750k and seemed to fix it when I took the idle screws out another turn. Also the jets I bought are OEM Keihin ones. One thing I may do if I can find time this weekend is do a 3000 mile check up on it to make sure everything is in order.



EDIT: updated with picture of exhaust

[DaveBarbier]

One thing I may do if I can find time this weekend is do a 3000 mile check up on it to make sure everything is in order.

Make this a priority.

And regarding terminology, you say "idle screws" but there is only one idle screw and this is the big thumb screw on the right to adjust idle. You probably mean idle mixture screws (IMS) which there are 4 of. One on each carb. Those look like PD46(a?) carbs so those control fuel and not air. Out for richer, in for leaner.

[Scott S]

 And if you still have the stock air box, buy some intake boots and re-install it. It'll be MUCH easier to tune than with pods.

 Clean fuel system : tank > petcock > carbs
 3K Mile tune up, then carb sync/settings. Carb work comes last.

[Bankerdanny]

Based on that tank and seat definitely a K.

The '77K used PD series carbs, which are very different from the carbs used on the '77 F.

[mitch5069]

yes correct I am referring to the IMS

Also I really appreciate the quick responses, thanks. I will keep this going when I have updates, might be in a few days though.

[Tews19]

Nice 550. As stated get some boots for the airbox. Also there is a set of matching side covers on Madison or northern WI for your bike. Real cheap price too. Take a look

[Deltarider]

CB550K3 it is. Parts list is here: http://www.honda4fun.com/pdf_parts_list/pdf_spac500-550/CB500-550_K3-K4.pdf

[BomberMann650]

Nice K bike!

4into1.com is another good resource for parts

[flatlander]

And if you still have the stock air box, buy some intake boots and re-install it. It'll be MUCH easier to tune than with pods.

this deserves repeating. get it to run properly first without putting new variables like pods in the mix.

[mitch5069]

CB550K3 it is. Parts list is here: http://www.honda4fun.com/pdf_parts_list/pdf_spac500-550/CB500-550_K3-K4.pdf

so page 36 and 37 are for my model carb? I only see one jet aside from the idle mixture screw, is this correct? I feel like any carb I have seen before has the IMS, slow jet and a main jet. Just checking on this.

[Deltarider]

Why don't you turn some more pages? Laziness? There are at least 8 pages dealing with the carbs.

[mitch5069]

Why don't you turn some more pages? Laziness? There are at least 8 pages dealing with the carbs.

I'm not sure what your trying to get across with this post??

There does look to be "at least 8 pages dealing with the carbs" but my understanding is that only two of those pages, 36 and 37, deal with the 550k3 model carb internals which is where I assume would describe the different jets. I guess I am just looking to understand what factors in the carb control the A/F mixture.

thanks

[flybox1]

shop manual download.
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual

[SOHC4 Cafe Racer Fan]

Since this is a project, I would suggest you move it to the Project Bikes Board (see link/button below to move thread). That way you can keep a running thread on issues that come up and show your progress on the project.

[Deltarider]

https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653507/24a1fc97eff08d37ffff8517ffffe41e.pdf Scroll down to your carbs. p175

[mitch5069]

https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653507/24a1fc97eff08d37ffff8517ffffe41e.pdf Scroll down to your carbs. p175

thanks, this helped alot.

So the electric start does not work on the bike so I am only working with the kicker. I took the carbs apart and adjusted the need to 3rd clip from the top and IMS set at 1.5 turns out to compensate for the UNI pods. I could not get the bike to start. So I took the carbs apart again and put in 100 main jets. Bike fired up with a few kicks but seemed to only idle with the choke pulled and seemed to lag when I cracked the throttle. I pulled them apart again and took out the slow jets, turns out they are 42 and two of them were blocked and one of the main jets and tube came loose. Cleaned the jets so I could see through them and put them back in. At this point I am running as follows:

IMS = 1.5 turns out
42 slow jets
needle at 3rd clip from the top
100 main jets
UNI pod filters

the bike fired up with some choke, I let it warm up then I cut the choke to it and it would not go down to normal idle. Seemed to be up at 4k or so (I do not have the tach hooked up). I check the idle adjustment and backed it off the entire way but it still stayed that high.

I think I'm going to order some stock size 38 slow jets and in the mean time try the same set up with the needle on the 2nd  clip and see what it yields. Then hopefully when the 38s come in try those with 2nd and 3rd clip from the top.

open for suggestions, thanks

[Scott S]

Have you done the 3000 mile tune up yet? If you haven't adjusted the valves and set the timing, you're wasting your time working on the carbs.

 Those carbs have a fast idle cam. Are you sure you have the choke cable installed correctly?

[mitch5069]

Update: I set the tappet clearances, adjusted the points (the clearances were less than what the service manual recommended), but I had some problems checking the ignition timing.

per the service manual when checking the timing on 1-4 points it states to disconnect the blue wire and rotate the crank with the timing light on ground and the contact itself. The problem is the light never comes on when the blue wire is disconnected. If I connect the the timing light to ground and the disconnected blue wire then it stays on the entire revolution of the crank shaft. If I leave the blue wire connected to the points and connect the timing light to ground and the contact it comes on at this point shown below:


When checking the 2-3 points the light comes on at this point:


what are you thoughts on the blue wire connected vs not connected? Also this shows that my timing is off correct? the "F" should be aligned with the tick marks rather than the number right? below is an overview shot of the points if anyone needs it for reference. I would like to note that after these adjustments I have not had a chance to try to start the bike again to see if of this fixed the high idling problem, I was waiting to see what to do with the timing before that.

[DaveBarbier]

I've never read that you need to remove the blue wire to check static timing. What book says that?

Just connect your timing light to ground with one lead and on the small screw where the points wires are connected. Just be sure that lead doesn't ground to the points plate or anything.

Turn the key to 'on' and the kill switch to 'run' then slowly spin the motor in the correct direction using the kick starter, large bolt on the rotor on the left side or carefully use that nut in the picture...it's like a 23mm or something.

The light should come on right when the F mark hits witness mark. If it doesn't, loosen the plate slightly and adjust until it does. It tends to move after you tighten everything down so verify a few times.

If the brightness we see in the picture is from your test light then you seem too advanced. And that makes sense as to how the points plate is clocked. Moving the plate CW retards the timing and should get you closer.
(Someone correct me if I'm wrong about CCW is advance and CW is retard, hard to visualize in the morning

[mitch5069]

I think it was from a service manual I found either on here or dotheton. I have it saved on my other computer. I thought it was a little odd..

I ended up setting it based on how you described. got it up and running an sync'd the carbs the best I could. I have a hard time keeping it idling in the 1,000 to 1,250 rpm range. I thought I read somewhere that was the idle speed to shoot for. I rode it around this weekend a bit with the high idle (around 2500 - 3000) and seem to run ok. The starter relay is fried so I'm waiting on one of those to come in and them I'm going to check the compression on it.

I had one question, looks like there is a breather on the top of the engine. Does this go to anywhere? Do I need to just get a hose for it and run it downward? thanks

[Bankerdanny]

A tube just runs down and either plugs into the bottom of the air cleaner or, if you have pods like my bike, to the swingarm.

That port shouldn't impact your synch.

[DaveBarbier]

Static timing with a test light is good to get you in the ball park, but to verify the advance timing you need to use a strobe.

Regarding air leaks, check with propane or carb cleaner where the intake manifolds attach to the head. There are o-rings there that could be hard and cracked.

Have you removed the plugs and looked at the color after a relatively long idle with a fan blowing on the motor? If not, post a picture of them in 1>4 order.

[mitch5069]

Static timing with a test light is good to get you in the ball park, but to verify the advance timing you need to use a strobe.

Regarding air leaks, check with propane or carb cleaner where the intake manifolds attach to the head. There are o-rings there that could be hard and cracked.

Have you removed the plugs and looked at the color after a relatively long idle with a fan blowing on the motor? If not, post a picture of them in 1>4 order.

I have checked several times with propane and carb cleaner. the engine only seems to rev higher when I put the propane up to the uni pod foam which makes sense. As for the plugs I have not removed them yet. It's been a bit since I last posted but I did make the move into a house and that seems to consume most of my time. Currently working on get the garage set up as a shop to start working on this bike again. Any way I did ride the bike from my old apartment to my house and it ran but idled at around 4k any lower it seemed like it wanted to die on me. I should also note that to start it I had to jump the starter solenoid with a screw driver. I assumed the solenoid was bad so I got on off ebay and installed it. I didnt know what side was positive and what side was negative and since it didnt seem to be called out I assumed there was no polarity to it. Please let me know if that was a bad assumption. Anyway after I installed it I tried the start switch and nothing. Well almost nothing, the bike doesnt crank over nor could I hear the solenoid do anything but the headlight did dim... now I'm scratching my head on this one. Any advice is greatly appreciated. I'm starting to look at a wire diagram now but I cant see what could be wrong with it since the light is dimming ...

Thanks in advance