Topic: First bike 76' cb 550

[76 cb550]

Hello everyone. 
   I recently purchased a motorcycle thinking it would be a cheap way to get around...I figured it would be a lot cheaper to buy an old bike that ran and fix it up.  I haven't worked on engines much and I needed some experience in the field cause it's usually a lot cheaper to fix something yourself than to pay someone else to do it.  So I thought a bike would be a good way to gain that experience.  So here I am with a beautiful blue 76 on my carport that doesn't run well enough to practice on.
   I'll start at the beginning.  I bought the bike, brought her home, and tried to start her.  Kick started a bunch of times and nothing.  Fooled with the choke, the petcock, and the idle screw (the previous owner told me 2) and nothing.  She'd grab a little but wouldn't turn over.  Then I noticed that the lights were going in and out...electrical problem.  A friend told me to charge it over night but all the explosion warnings on the charger and the battery made me nervous.  So I ran the batt. over to my autoparts store and they charged it up for me in about 20 minutes.  The batt. boiled over and was ruined so I bought a new one.  Put it in set everything to my satisfaction and jumped on that kickstarter (didn't know I had an electric starter yet) One kick, two kicks, and vroom she started so easy a single tear ran down my cheek.   I looked at the tach. and she was idling too high so I started fiddling with the idle screw but I couldn't really notice any difference.  I fiddled around for a good long while before I thought about the choke.  I turned "off" the choke and VVVRRRROOOOMMMM she flies up around 7000 rpm's or more and is screaming that she's gonna blow up any second.  I'm panicking a good bit right now and not really thinking clearly so I turn the key and nothing happens she's still screaming...now I'm really panicking I don't know what to do...I turn the key again and she dies.  I get off go inside smoke a cig and then get online to figure out what I had done wrong.  Turns out I turned the choke the wrong way...I felt smart. 

Anyway a few days later I took her out for a spin around a parking lot and all went well, until I let my brother in law try her out.  ten feet and she died, another ten feet and she died another ten feet and she died.  I probably shouldn't have taken her out at all in hindsight...she wouldn't idle unless we used the choke to keep her at around 3000 rpm.  I'm a newbie I know...I'm making mistakes... but this is a learning experience for me more than anything else.  Anyway I got back on her and I couldn't get her to go either.

I did some research and performed a compression check 120 across the board.  Lower than spec but I was told it was fine. 

after the comp check I let her run for a little while to recharge the batt.  She had lost batt. power during the test ride.  after she ran for about 15 minutes she started leaking a lot of oil from the oil pan and the gear selector.  I tried tightening the bolts on the oil pan and one of them broke off on me.  I've got an ezer out to get it out but I think if i pull the oil pan part of the bolt will be sticking out and I can grab it with some vice grips.  Just gotta pull that exhaust pipe off so I can get to the bolts holding the oil pan on. 


Sorry I just realized i'm kinda rambling...I'll work on that in future posts.

I think the idle problem is a vacuum leak or clogged up carbs.  I'm planning on cleaning out the carbs and performing a leak check with some wd 40. 

I'm open to suggestions, questions, and constructive criticism.

[mattcb350f]

I think the idle problem is a vacuum leak or clogged up carbs.  I'm planning on cleaning out the carbs and performing a leak check with some wd 40. 

You're on the right track I'd say.....sounds like fuel starvation to me. This can be a number of things including the carbs. Could also be cloged sediment bowl up by the tank (usually rust), so make sure after checking out the carbs that the fuel flows freely out the line.

[76 cb550]

will do.  Your talking about the filter attached to the tank right?

[mattcb350f]

Yup, but I've also seen a peice of rust sit right on top of the stand pipe in the tank and cause stopage.... got to clean'er from there to the jets 

 Matt.

[TwoTired]

None of the American model 76 CB550s had a choke coupled to the throttle.  If you have a choke knob at the bars then it's at least a 77 model. 

IF it is the choke lever on the carbs itself.  The only reason for the engine to race is that you have the idle knob set too high and it is running off the mains/throttle valve fuel path inside the carbs.  Or, perhaps a vacuum leak, but the where is fuel coming from?

Anyway, the idle jets are only about 0.016 inch in diameter, so it doesn't take much foreign matter to stop flow through the idle jets and ruin your idle.  If bits are floating around inside the carbs, then the problem can come and goes as the fuel sloshes around.

So, explain why you think it is a 76 model, and if you can post the numbers stamped on the carbs, then we can get a better idea of what you have to do to get the carbs happy again.

IMHO, almost all run problem statements should be prefaced with tuneup history, and include modifications that have been done from stock configuration (like exhaust and air filter changes).  The more variables that can be eliminated, the more directly the real problem can be addressed.

The 76 model has a fine mesh filter just above the fuel petcock.  It can easily be damaged during removal, and these get quite difficult to remove once rust begins to take hold in the tank.  I would look first inside the tank with a strong light (not a match) to look for signs of rust.  I would also either catch and examine drainage from the float bowls to observe fuel quality, or remove a float bowl  and look in it for foreign matter.

Cheers,

Post a pic of the bike.

[76 cb550]

The seats off...I'll take one with the seat on if you like. 

The choke lever is on the carbs.  I'll post the numbers on the carbs if you like.  I don't have them written down.  I'll go get them in daylight.

Tuneup history...let's assume that little or no work was done on her before I got her.  All I've done is a compression check, batt. replacement, replacing ducktape that was used as an insulator...with electrical tape, and I messed up the idle screw.  I fiddled with the idle screw when I was practice running her but when the idle dropped below 2000 she'd die when you gave her gas.  She idles at around 3 now and still does that sometimes.  If the idle was taken down to 1000 (spec) she'd die on her own.  I'm planning on going through my haynes, shop, and owners manuals and performing all the maintenance I can perform myself on the next warm (40degrees atleast 30 with no wind) day. 

I will examine the tank for rust. 

The title says '76.

[pollpegj]

That thing has some weird parts on it, the muffler extensions, front fender guard thingy and headlight visor, looks as though somebody has doe some previous modifications to it.

[76 cb550]

yeah, can't argue with you there.  Would you like a close up shot of anything?

[TwoTired]

Looks pretty much like it started life as a  76 CB550K.  Those muffler additions are unique.  Are they just welded on, or have the muffler guts been modified, too?

Been repainted, FYI, Candy Garnet Brown was the original 76 K flavor. Is this a US bike?  Front turn sigs are 1974 style.

You carbs should be either 022A or 087A Keihins.  There is a large head screw at the bottom of each float bowl.  It's the bowl drain.

Looks like you have and ignition modification, too.

Good looking bike.  They are pretty fun to ride.

Next time you run her, you should check the head pipes for heat.  Cold ones mean they aren't firing.  And, that's the cylinder/carb that is giving trouble.  Don't go grabbing exhaust pipes.  Flash touch and wait for the heat signals to get to the brain.  Increase the touch frequency to your comfort level. 

You've got some pipe discoloration there.  So, if not now, at one time the cylinder was run quite hot, like it would with a plugged idle jet starving it for fuel.  Plugged idle jets also make the engine wheezy/hesitate when giving it throttle.

The idle screw is set when the engine is running properly and at full operating temperature.  When cold, expect it to NOT idle without your hand holding the throttle open a bit.  It should only take a few blocks of riding for it to idle at the warm idle setting.  But, it does depend on the outside temps just how fast it warms up.  If it seems really cold blooded, check your spark plug heat range.   NGK D7EA is correct, not the D8EA the CB750 uses.

Let us know your progress.

Cheers,

[Deltarider]

Looks like those mufflers are giving birth to new ones.   

[Deltarider]

Don't panick. I'm prepared to adopt them.

[76 cb550]

so I should run her and let her warm up (how do you know if she is actually warm?) and as she warms I should feel the exhaust pipes for warmth?  I have some gloves made for this kinda thing so ok but kinda scary.  Brother in law burned himself quickly on one of those.
It'll be a while before I can run her again.  I cracked a bolt on the oil pan and I have to replace it aswell as the gasket.

muffler:  are you talking about those pipes sticking out of the end?  I haven't checked Didn't know it was a mod.  I'll get back to you on that shortly.

the VIN starts with cb550- does that mean it is neither an f nor a k?

How do I know if it's US?

[Deltarider]

Tank, exhausts and sidecovers indicate it is an K. You may want to identify your carbs by reading the stamped on number. This pic shows you where you can find it.

[TwoTired]

so I should run her and let her warm up (how do you know if she is actually warm?) and as she warms I should feel the exhaust pipes for warmth?  I have some gloves made for this kinda thing so ok but kinda scary.  Brother in law burned himself quickly on one of those.

You can pass your hand through flame if you do it quickly.  A second or two later, your hand feels warmer.  Same technique for the pipe.  Flash touch & remove, wait for finger heat to get to brain.  Repeat until you get a sense of temp. move on to the next pipe.  Always assume it's hot till proven otherwise.  Don't grab and hold till you feel heat, as it can surely be hot enough to burn you.

Adjusting carbs is done with an engine at operating temperature.  That's when to set the idle knob.  The idle knob CAN be set high enough that the carbs are using the fuel passages for driving rather than the fuel passages for idle speeds.  If an idle jet is blocked, the cylinder may run at a higher throttle setting, but it will run lean and hot at that higher throttle setting and won't run at all at a low or idle throttle setting.  This means the pipe can be blazing hot with the throttle open, and colder than the others while the engine is idling.   Then again, if ALL the idle jets are blocked (it's possible) it won't run at all at idle and all the pipes should be hot when the throttle is held open, either by the idle knob or the twist grip.  This is because the idle jet provide almost all the fuel at idle throttle, but still provides some flow at all throttle positions, and it's loss creates a lean condition.

muffler:  are you talking about those pipes sticking out of the end?  I haven't checked Didn't know it was a mod.  I'll get back to you on that shortly.

Yes, that's a mod for sure.

the VIN starts with cb550- does that mean it is neither an f nor a k?

No, yours is a K model.  The Vin Number for 76 model Ks begins at :  CB550 - 1230001

How do I know if it's US?

Unless you know it was imported from a country other than Japan, it's the country where it currently resides.  This forum is comprised of international members.  Unless you state where you are, I don't know what country it is in.  European models have weird differences from US models.

Cheers,

[76 cb550]

Planning on cleaning out the carbs when I get the opportunity.  I have to order some parts anyway. Should I go ahead and order kits for the carbs while I'm ordering the other parts?  Or Should I take em apart find anything that's busted and then order parts as needed?  The bikes old as dirt and I'm inexperienced so I'm pretty sure either a part will have to be replaced because it's old or because I screwed up and broke it.  Anything else that I should look into replacing while I'm at it?

Do you guys agree that 120 across the board is good compression?  170ish is book spec.  The book says less than 140ish is a problem...

[TwoTired]

I use the Honda carb kits.  They have all the rubber bits you need to replace 30 year old hardened rubber. Anything metal is reused after cleaning.

120 is fine.  You don't have the low volume gauge like what Honda used.  Besides, did you check compression with a warm engine and the choke and throttle open?

Cheers,

[76 cb550]

I thought it was warm.  I'm not sure how to tell exactly.  I let her run for around 10 min. at around 3500-4000 rpm.  Not sure about the choke.  It was very close to open, probably not fully open.  throttle was open fully.

[patpollin]

my '76 550k registers 120 psi in every cylinder also.  It seemed low to me too, but the bike pulls hard so I decided it was alright. 

[76 cb550]

I've hit a wall.  The boots between the carb and the airbox are total crap.  They have to be replaced.  Are my only options replace the airbox and put on pods?  If I do the pods how hard is that going to be?  Can I do it myself or do I need to factor in cost of repair labor.

[TwoTired]

I've read here on the forum that David Silver Spares has new rubber couplers for sale in Great Britain. See the FAQ for contact info.  eBuy for used ones, of course.

While descriptive, "total crap" doesn't really relay what is actually wrong with the couplers you have.  Did you tear them upon disassembly?

Pods are an option for many.  But, I avoid them for many reasons.  Almost certainly you will have to re-jet your carbs to get he bike to perform as good as the stock air box set up.

Do not worry about your compression figures.  Unless you are racing, those numbers are plenty good for a street bike.

Cheers,

[76 cb550]

Sorry I had a bit of a bad day.  an extra 130 dollar repair will do that to ya.

the rubber boots between the carb and the air box have holes large enough for me to stick two fingers in them.  I've wrapped them in electrical tape as a temporary fix. 

Are you saying that I can just get the rubber parts without having to buy the whole air box?   I thought the "couplers" were attached to the air box. 

I'll check that faq right now.  Thank you

[TwoTired]

I thought the "couplers" were attached to the air box.

They are.  But, the glue used by Honda is not that tenacious.


Cheers,

[76 cb550]

So I'd have to glue them on myself, that's not so bad i guess?  I don't suppose there is a cheap yet effective trick to fixing broken couplers...  I took a look at that site and I can't find couplers.  He has the air box for thirty euro (not bad) and the clamps but I don't see couplers.  Thanks for suggesting I look at the faq.  lot's of helpful part location links in there.



This pic was taken just after I got the bike.  Those are wrapped with electrical tape now

[TwoTired]

I had a previous dialog with Jonesy about those couplers.  He stated, if I remember correctly, that the couplers for models prior to 77 were available from DSS.  I have no direct experience.  But, I got the impression that phones calls/email was involved.  Perhaps you would get better info with a PM to Jonesy?

I do know that American Honda did not sell those couplers separately. You had to buy the whole air box assy.    Perhaps the online order system at DSS is based on Honda's part number scheme?  I got the impression that DSS found an after-market supplier for those couplers and as such they wouldn't have a Honda Part number.

I've taken those couplers out and put them back in.  Just for the giggle, mostly.      I didn't bother with any glue.

I don't know how to repair the torn one you have.  I'd find a replacement somewhere.  Tape should work as an interim patch.  But, the fuel fumes will likely attack/dissolve the adhesive.  There are enough of these bikes undergoing cafe mods with pods, that another set of couplers should be available with some patience and scrounging.  I bought an air box/filter a couple years ago from eBay for $15, to restore a pod infested bike I acquired.

Did you post a request in parts wanted?

I expect you are anxious to get the bike repaired and rideable.  But remember, the bike took 32 years to get in it's current state.  Maybe fixing it over night is a bit ambitious?   Persevere and you'll have a sweet bike to put a big smile on your face.

Cheers,

[76 cb550]

Man I appreciate your attitude.  It's not that I'm in a huge rush to get it fixed.  I'm just scared that I made a big mistake buying an old cheap bike.  I thought I was sooo smart.  "I'm gonna buy an old bike and fix it up.  I'll save so much money"  I'm inexperienced and afraid that I've made a mistake.  I realize now that the couplers aren't that big a deal.  I already found a brand new set for 50-60 bucks on ebay.  I'm not getting them.  I'm gonna go junk yard hunting when I get the chance and try to find some that aren't torn.  I'll PM jonesy in the meantime.  thank you again. 

What do you mean you didn't bother with glue?

TY for that link.   A bit tough to maneuver but I found em.