Topic: CB550 Refurb

[Antiquar]

Hello all.

On Friday I bought a 1974 CB550. It had been sitting for some period of time. Maybe a year but nothing crazy AFAIK. Here she is in all her glory:


It was running, barely, with fresh gas on Friday. Since then I've adjusted valves (mostly in spec), reset timing (cylinder 2-3 a little retarded) and breaker gaps (gaps were way out of spec), changed oil/filter, and gave the carbs a quick clean (the slide on carb #1 had seized from bad gas. Remarkably most of the carbs still looked pretty clean).

Now the bike is running much better, but will still need a lot of tune up. I've got quite a few new parts and rebuild kits on order, hoping to make quick work and get it purring, as it will be for my girlfriend to ride as her first bike:


I'm more of a Guzzi and BMW guy, but she had her heart set on a Honda. This is my first bike from the marque, so I'll mostly be posting here for advice and possibly to document the refurbishment.

[flybox1]

Right on!  Welcome to the forum.   I just finished a 74 550.  A really fun displacement.
Glad you still have the original exhausts.  Looks in really solid condition.
Continue to drill down on the timing/advance until you get it perfect on both, then top it off with a good vacuum sync of the carbs.

[Antiquar]

Thanks!

My current plan of attack is to go over the entire ignition system, replacing bits where necessary, then do a good carb sync.

The major running issue right now is an erratic hanging idle. Doesn't seem to be an air leak, but there are too many variables right now to know with certainty what the issue is. I'm hoping going over the ignition system and carb sync will solve the issue and I won't have to do a full rebuild of the carbs. 

I can tell already that tuning this bike will be a lot more finicky than the twins I'm used to.

[540nova]

I like how her hair matches the tank and side covers.


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[Antiquar]

I like how her hair matches the tank and side covers.


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Thanks 540. I like that, too. 

[calj737]

Nice looking stock condition bike. It also appears that someone has been in that motor before as many of the JIS screws are stripped. Get a proper set of JIS drivers to service that engine and leave the Phillips screwdriver in the drawer. You won't strip the screws, they'll remove rather easily, and you'll save yourself countless hours of aggravation.

There are rubber O-rings between the intake manifold and head that often dry-rot due to age and heat. They can be a difficult to identify source of a vacuum leak (hanging idle). Carbs would have to come off, and the manifolds too, but if you can't resolve the idle, then best to look at the service.

A fresh front tire too at a minimum 

[540nova]

It also appears that someone has been in that motor before as many of the JIS screws are stripped. Get a proper set of JIS drivers to service that engine and leave the Phillips screwdriver in the drawer. You won't strip the screws, they'll remove rather easily, and you'll save yourself countless hours of aggravation.

Probably beyond the point where JIS screwdrivers will work. Liberal use of Kroil or PB blaster, a #3 bit and an impact handle will be your friends here. Then replace all the hardware with stainless steel Allen head fasteners, with anti-seize on the threads.


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[flatlander]

pretty nice bike in original shape. should be good fun once you get it running well.

[Antiquar]

Nice looking stock condition bike. It also appears that someone has been in that motor before as many of the JIS screws are stripped. Get a proper set of JIS drivers to service that engine and leave the Phillips screwdriver in the drawer. You won't strip the screws, they'll remove rather easily, and you'll save yourself countless hours of aggravation.

Yeah, someone has definitely been in it. Some heads are a little mangled. Will probably get a replacement set of screws when/if I have to dig into the motor. Unfortunately the clutch adjustment screw (bottom of clutch cover) has been mangled as well, and several threads are stripped. it is adjustable within a certain range, but should definitely be replaced. I can't seem to find it on any fiche.

Anyone have tips on replacing one of these?

There are rubber O-rings between the intake manifold and head that often dry-rot due to age and heat. They can be a difficult to identify source of a vacuum leak (hanging idle). Carbs would have to come off, and the manifolds too, but if you can't resolve the idle, then best to look at the service.

A fresh front tire too at a minimum 

Oh yes, tires will definitely be replaced before I call the bike roadworthy. I've already received a new set of airbox and manifold boots. Hoping to install them this weekend, along with replacing the points, plugs, doing a thorough carb cleaning, and a carb sync, and miscellaneous other bits.

[flatlander]

Unfortunately the clutch adjustment screw (bottom of clutch cover) has been mangled as well, and several threads are stripped. it is adjustable within a certain range, but should definitely be replaced. I can't seem to find it on any fiche.

Anyone have tips on replacing one of these?

you can get the original part, but only together with the complete lever:
http://www.cmsnl.com/honda-cb550-four-1975-cb550k0-usa_model465/22831333020-lever-clutch-adj_22831333010/#.WAqAFpN96Rs

if you want to ask your friendly machinist to make you one, look here and keep scrolling down - i've had a similar problem:
http://forums.sohc4.net/index.php/topic,134863.msg1642341.html#msg1642341

glad to hear you're buying her new shoes, too 

[Antiquar]

you can get the original part, but only together with the complete lever:
http://www.cmsnl.com/honda-cb550-four-1975-cb550k0-usa_model465/22831333020-lever-clutch-adj_22831333010/#.WAqAFpN96Rs

if you want to ask your friendly machinist to make you one, look here and keep scrolling down - i've had a similar problem:
http://forums.sohc4.net/index.php/topic,134863.msg1642341.html#msg1642341

Yikes, your case looks a little worse. I found a clutch cover on ebay that has the complete assembly for cheap, so I bought that .

Today I tuned up the ignition system, replaced intake/airbox boots and cleaned carbs thoroughly (also replacing needles, jets, screws). The bike fired up and purred nicely. No more hanging idle! Unfortunately carb 1 is pissing out gas through the overflow line, so the carb bank will have to come back out for another checkup.

[flatlander]

good news, congratulations!

you might just have a stuck float, or a bit of debris in the float valve. if you tap the bowl of the offending carb with the handle of a screw drivers or something, does it go away? then it was the float. if that doesn't help, run the bike with petcock closed until it dies. after that, check if it still does the pissing.
also, are you sure the float hight is set correctly? of it's completely off you may have such high fuel level that it goes into the overflow. best is to check with the clear tube method, if you're familiar with it?

if all this doesn't help there's still no need to pull the carbs. just take off the bowl, as it's no. 1 it will be easy to get to the parts. now you can get to the float and needle valve and should be able to do whatever you have to do.

[Antiquar]

Thanks for your continued advice, flatlander.

I took off the carbs. The float level on carb 1 was a bit high. I readjusted and sprayed some cleaner in the valve seat. Put it back together and no more leak! I hope that is the last time I have to open up these carbs for a long while.

Unfortunately some more tuning issues have arisen. When the bike is hot the idle sometimes hangs a bit (maybe 5-10 seconds at 2k rpm before settling back down where it should be). I performed a vacuum sync to no avail. When cold it falls back to idle rpm as it should.

The bike DOES have great response and power when on the throttle however, especially for a 42 year old machine (as well as I can tell, this is my first CB so I'm not sure how it *should* be). I can see why people like these bikes.

WD40 on the airbox/intake boots did not reveal any air leak. Perhaps I need to renew intake manifold o-rings. I did notice the crankcase breather has a slight tear on its connection to the airbox--wonder if this could also be my air leak.

[calj737]

It could be the timing advancer mechanism. The springs get fatigued over time and the mechanism might need cleaning and lubricating. There is a small alignment mark on it if you disassemble it 

[Antiquar]

Interesting. Sounds like it might be it. I just have to get a hold of a strobe timing light to check. 

[flatlander]

I took off the carbs. The float level on carb 1 was a bit high. I readjusted and sprayed some cleaner in the valve seat. Put it back together and no more leak!

glad it helped. you seem to be pretty cool with taking carbs on and off repeatedly. do you have a special technique? or you have a pet octopus with strong and long arms?
i myself try to avoid taking them off as much as i can and do as much as possible with them in place.

[Antiquar]

glad it helped. you seem to be pretty cool with taking carbs on and off repeatedly. do you have a special technique? or you have a pet octopus with strong and long arms?
i myself try to avoid taking them off as much as i can and do as much as possible with them in place.

 

Well I tried to remove the float bowl in place first, but I felt a screw head begin to strip. At that point I decided to take out the carbs. My only trick is to remove airbox rubber clamps before carb removal/installation. I find the clamps to be what really makes things dicey.

Unfortunately the god damned o-ring did not seat well and the float bowl is leaking (weeping) on the sidestand. Just ordered pre-shaped o-rings and will have another go at an in-place operation.

Suddenly I remember why I like fuel injected bikes. 

[Antiquar]

I spent some more time on the CB today, this time armed with a timing strobe.

The timing was slightly off (too advanced) across the board, so after resetting the points and gaps about five times it's pretty good now. Advance seems to work correctly on cylinders 1-4 (opens fully at ~2500RPM). Somehow cylinders 2-3 were not the same, but the retiming in conjunction with slightly enrichening the mixture has the bike idling pretty good now. I may get a cheap advance unit off ebay for comparison because I know it's not perfectly right yet... just okay.

I'll think hard about switching to an electronic ignition.

The bike is really coming together now. Things left to do:

• Replace clutch cover (for unstripped adjustment screw)
• Replace carb 1 float bowl gasket
• Fix up breaks
• New shoes
• Probably install engine guards as it will be ridden by a brand new rider 

[calj737]

You just need to replace the screws not the cover. Instead of replacing the timing advancer, clean and lubricate it. But do pay attention to the orientation of it, and the small, almost imperceptible alignment mark when reinstalling it.

[flatlander]

he's got a complete new clutch cover including adjust screw and all.

[Antiquar]

Yeah, for the clutch cover I have a complete replacement that will be quite simple to swap in.

I'll take another look at the advance unit. Totally possible I missed something. By the way, what kind of grease(s) do you all recommend to lubricate the advance and other timing parts?

[grcamna2]

Yeah, for the clutch cover I have a complete replacement that will be quite simple to swap in.

I'll take another look at the advance unit. Totally possible I missed something. By the way, what kind of grease(s) do you all recommend to lubricate the advance and other timing parts?

Welcome to the forum,we usually service the advance unit first so you don't have to repeat the points/timing adj.
You won't need much grease on the advancer pivot shafts,just enough on the pivot shaft(keep the same number of spacer rings on the pivot shaft) and a tiny bit where the weights attach(it's best to take the advancer apart to do this imo) although a heavy,heat resistant type such as Permatex Ultra Disc Brake Caliper Lube which is silicone and synthetic and stands up well to heat w/ anti-fling properties is good.The springs need to be checked before disassembly as you want to be sure there is equal and sufficient tension on each one.

Nice looking bike w/ such sweet preserved oem 4into4 stock exhausts,that's the benefit of living in that nice dry climate 

[Antiquar]

Thanks for the information all.

I've gone over the bike some more in the past few days.

I renewed the o-rings under the intake manifolds. The rubber there was quite hard and ancient. I'm pretty sure there is no air leak at this point.

I re-examined, cleaned, and lubed up the advance unit. I retimed the points. I performed another vacuum sync.

Unfortunately my hanging idle (when hot) issue remains. I am inclined to believe something is still wrong with ignition, as if I rev the bike under ~2500 it regains idle quickly. It's when I give the bike a good handful of throttle that it hangs. Though, when the bike is cold and operating correctly, the advance seems to open and close on time (as seen with a timing strobe). Checked both 1-4 and 2-3, and timing is correct under these circumstances.

I'll probably start from the top with a fresh tune up and plugs and see what happens.

[b52bombardier1]

Try some new springs on the spark advancer counterweight arms. Or at least look at the spark advance with a stroboscopic timing light.  That will tell you if the springs are strong enough to bring the arms back in at middle to high rpm.

Rick

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[grcamna2]

Try some new springs on the spark advancer counterweight arms. Or at least look at the spark advance with a stroboscopic timing light.  That will tell you if the springs are strong enough to brings the arms back in at middle to high rpm.

Rick

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