Topic: I dropped my '74 CB550 and now it's a mess. Help!

[kylenoland]

So I just picked up a 74 CB550 over the weekend. I already know the bike has a charging problem. I'm a pretty new rider and this is my first bike with a kick starter. On Sunday night I managed to drop it while trying to kick start it. I had ridden the bike for many hours every day all over town prior to that, but since then, a couple of weird issues have popped up and I don't know where to start diagnosing whatever I messed up.

• It won't kick start at all now without full choke (parallel to the ground) and the throttle twisted pretty good at the same time. It roars to life but dies immediately before I can adjust the choke.
• The electric starter struggles but will eventually start the bike with no choke and no throttle.
• The bike idles just fine after it warms up for a couple minutes and I can rev the engine as much as I want and it returns to idle right away, but it completely bogs down and dies under any kind of load, in any gear. Prior to dropping it the other night I rode it all over and it was very solid feeling and responsive in every gear.
• There is a fast clicking sound coming from the engine. I can't be certain this is new, but now that I've really been paying attention it is quite obvious.

I've done some googling and decided to start with a new rectifier/regulator as the first troubleshooting step in the charging system fix because the part was cheap and easy to install.

I've checked all the spark plugs and none of the cables or boots are loose.

I'm really at a loss here about how I managed to make such a mess from a fairly low-impact drop in my driveway.
I've ordered a shop manual that should arrive tomorrow. Can anyone give me some clues or steer me in the right direction with what to start troubleshooting?

[robvangulik]

What side did it drop on?
Any obvious damage?

[Deltarider]

You may have two or more issues.

I had ridden the bike for many hours every day all over town

Not a good thing for any CB500/550. It's not a bike town so you may have encountered the usual suspect: a more or less depleted battery, simply because it wasn't above 3000 rpm sufficiently long enough. US specialties like headlight always on (even before started!) and good for nothing marker lights that consume 16 Watts nevertheless, are not very helpful either. I'd take your bike to the open road for a longer ride, but wouldn't start by replacing parts (here known for their reliability), not before you know for sure they're the culprit.

I already know the bike has a charging problem.

Yesss... well... now... when I look at the epidemic of replaced r/r units overthere and the very few here... Let me say I have my doubts. Reason: see above.
My bike has fallen over innumerable times. Sometimes the floats had to get into their routine again, although I cannot explain exactly how and why. I never had to open the carbs for that, btw. If your bike has no crash bars and has fallen on its right side, then we would need to see what damage the points cover has...

[flatlander]

i'm with delta here: you probably don't have a charging problem, but didn't get the bike the chance to run in a way that actually charges the battery
take it out for a good long ride in the country and see what you get. a 20min highway run at 7k rpm and above may "clean up" some other issues as well - a.ka. italian tuning for getting rid of carbon deposits and other crap that can accumulate when the engine is underutilised on short trips with many stops and long idling.

for the rest, describe the fall a bit better and maybe post some pics. it does sound unlikely that a mere tipping over would cause some engine damage.

[strynboen]

yes thek the volt"s at the battery..if you are under 10-11 volt the engine starts not on the elektric starter..and even is hard to kick...turn light on/OFF at the test..use a voltmeter direkt at the battery..must hold 12 volt or more..even vith light on..and cut engine( test only for a short)

[Deltarider]

it does sound unlikely that a mere tipping over would cause some engine damage.

+1 As far as the left side I can only think of the choke lever, as far as the right side I can only imagine the points cover and - I hope not - beyond...
Before suspecting other components, this first: charge battery. Leave it alone for a couple of hours. Check then if it reads 12,6 V minimum. Connect voltmeter and do an electric start. Voltage should not drop below 9,5 V whilst cranking.

[calj737]

Your use of CHOKE and throttle to start your bike is NOT correct. Use the CHOKE to start the bike, then close the CHOKE (open to normal riding position) and then simply use the throttle. Your IDLE screw might need a bit of tinkering. Its rather likely you've fouled the plugs a bit with your starting technique too.

You should close the fuel petcock when you stop the bike. Open it, turn the key ON, then start your bike. This allows the fuel to fill the carbs just enough to be ready for riding. If you leave it on always, its possible that it will flood the engine. Possible, not always likely.

Don't start replacing parts simply because you "think" they're bad. There's ample reasons why your battery is weak. Falling over could have dislodged a ground cable, riding style may be depleting the battery (as was said above) and it could be that you're not revving the engine high enough while riding to charge the bike. This motor needs to be above 2,500RPMs before it starts producing surplus voltage to the battery.

Unlike your car where the alternator is always generating voltage, the SOHCs (most models) need to be running above a certain RPM or they are operating in a deficit to the voltage needs. This depletes the battery after a while. Given you're new to bikes, and these especially, it would not surprise me to find you "babying" the bike around town, shifting under 3,000 RPMs so as not to "hurt" this old bike. This is opposite of what the motor wants, and needs. Ride above 4,000 and often above 7,000. You WON'T hurt the bike. It will wake up, smile, and beg for more. Trust me/us on this.

If you need help running through your charging system to identify IF you have a problem, grab a decent multi-meter and a battery charger. Then let us know and we will point you in the right direction.

Welcome!

[evinrude7]

So I just picked up a 74 CB550 over the weekend. I already know the bike has a charging problem. I'm a pretty new rider and this is my first bike with a kick starter. On Sunday night I managed to drop it while trying to kick start it. I had ridden the bike for many hours every day all over town prior to that, but since then, a couple of weird issues have popped up and I don't know where to start diagnosing whatever I messed up.

• It won't kick start at all now without full choke (parallel to the ground) and the throttle twisted pretty good at the same time. It roars to life but dies immediately before I can adjust the choke.
• The electric starter struggles but will eventually start the bike with no choke and no throttle.
• The bike idles just fine after it warms up for a couple minutes and I can rev the engine as much as I want and it returns to idle right away, but it completely bogs down and dies under any kind of load, in any gear. Prior to dropping it the other night I rode it all over and it was very solid feeling and responsive in every gear.
• There is a fast clicking sound coming from the engine. I can't be certain this is new, but now that I've really been paying attention it is quite obvious.

I've done some googling and decided to start with a new rectifier/regulator as the first troubleshooting step in the charging system fix because the part was cheap and easy to install.

I've checked all the spark plugs and none of the cables or boots are loose.

I'm really at a loss here about how I managed to make such a mess from a fairly low-impact drop in my driveway.
I've ordered a shop manual that should arrive tomorrow. Can anyone give me some clues or steer me in the right direction with what to start troubleshooting?

kyle, i had the same problem until i learned the bike needs to rev in order to charge.  before i had the bike and myself licensed i would tool around the neighborhood shifting early and taking short rides.  battery had to be charged often.  listen to what these experienced members say.  they know their stuff.  as far as dropping the bike goes, i've done this numerous times.  my points cover is trashed.  it really shouldn't hurt anything internally.  one time my stepson dragged the trash can past my bike and knocked it over while i was at work.  my wife called frantic "there's gas flowing everywhere!".  she couldn't lift the bike up.  i wasn't about to leave work to go pick up the bike.  all that happened was i lost about half a gallon of gas.  got home and picked up the bike, let it sit for a while.  started up just fine.  good luck. 

[TwoTired]

1 - charge the battery. Obtain both a multimeter AND a battery charger with a 1 amp chrage rate. Charge the battery for 10 hours, or ride the bike for ten hours never letting the RPM go below 3000. And turn off the headlight. (which you should do during start operations, anyway.)  Use the multimeter to report battery voltage
Before charging, after charging, at idle ,2000, 3000, 4000 rpm with lighting off and with lighting on.

2- Remove your spark plugs and examine the electrode tips and insulators.  Excessive choke use can soot the plugs which shunts away spark energy.  If the carbs are in proper tune, they can self clean from such abuse with an 80MPH run for 15-30 minutes.  Needs heat and fire.  Otherwise replace sooty plugs with new.

Fyi, you probably threw money away replacing the r/r.

3- You should also tell us what mods have been made to the bike that make it different from stock configuration.

Cheers,

[markreimer]

I'll echo a few of the points here.

When I bought my first motorcycle, a SOHC4 CB750 K4 only 6-7 years ago, I couldn't believe the engines liked to be revved way up. It felt very weird to be cruising down the highway at 5-6K on the tach. Now I understand these bikes love being up there! Try riding a 350F, it doesn't even make an ounce of power till about 7K!

If this bike is new to you, I'd suggest making sure your valve clearances and cam chain tension are set properly. If those are out, your engine can make all manner of clicking sounds. It SHOULD make some noise though. These engines are not designed to be silent like a modern bike. When it's all set properly you have a lovely sewing machine whirring and clicking sound.

My 750 also had similar battery issues when riding in stop and go traffic for a long time. If you can, keep the battery on a battery tender when you're not riding it. Or at least take it out on an hour long (or longer) ride where the engine is kept above 4K. That'll get it up to full operating temp, burn off any moisture thats condensed inside the engine from repeated short trips, and charge up your battery.

As for starting, don't open the throttle wide open like that. If that is the only way to get your bike started, something is wrong. Again I'll suggest checking valves. I just set my friends 400F valves and he had a similar starting routine to you. Now it fires right up with no throttle. If valves, float heights etc are all set, this bike should fire right up easily.

Good luck, report back!

[BomberMann650]

When google searching for old cb info - add the keywords sohc4.net

Otherwise, you're gonna get a bunch of misleading info.

[Gene]

Yup. Rev the sh*t out of it. This holds true for the 750's and 550's. They respond, it is necessary. Even if you are "around town" never fall below 4K RPM unless you are stopped.

Charge your battery, change your plugs (which, as stated, are probably fouled), and run the bike harder than you probably think you should. Follow all of the good advice offered here and you should be right in no time.

[PeWe]

Important with warm engine before revving it.
No problem with max choke when starting it, reduce it a little when bike has started . You'll learn how warm engine needs to be when running with no choke at all. Maybe 5-10 minutes depending on the ambient temp.

[Deltarider]

The models with the chokelever at the side were not ment to ride with chokes (partially) on. Consult your Owner's Manual.

[TwoTired]

550s with choke on side can be riden with partial choke.  No stationary warm up is required.
Gear up for riding first.  Start with full choke, hand on throttle. Back off some choke when it starts and hold 1500 rpm, a bit more to ride off on your way.  You will learn how much choke to hold for cold riding by throttle response. If very cold, reach down and nudge some off periodically as the engine warms. You only need enough to give decent throttle response. In about a mile you'll not need any choke, and the idle you set previously when warmed up behaves as predicted.  No need to fiddle with the idle knob, as while ridding your hand is on throttle to hold idle speed.

If you insist on a stationary warm up, get a throttle friction lock / cruise control operated with your thumb to hold a little throttle during the warm up, in place of your hand.

Cheers,

[Deltarider]

The CB500/550 models with chokelever at the side of the carbrack are not ment to ride with the chokes (partially) on. There's a good reason for that: having the lever not in your view, you'll forget you have them partially on. Just keep your hand on the throttle. This practice is confirmed by the Owner's Manual. I guess Honda didn't want you to unnecessarily fiddle with a lever somewhere below that you can't see, but that's just a guess. No need to use the idle screw unless you plan to do things with your right hand (which I often do btw). These models don't necessarily need a stationary warm-up as they had a pretty rich idle, so just a bit of throttle as the manual suggests. With the arrival of models with the chokeknob at the handlebars, it's a different story. They had a leaner idle and a fast cam. For convenience the knob is now positioned directly in your view. Ofcourse you can choose what you like best. But if you need the chokes partially on whilst riding an old model, your idle is probably set too lean. 

[flatlander]

another thread where the OP hasn't checked in again. are we that scary 
oh well, at least it's an occasion to quibble about to choke or not to choke!

personally, i start up at full choke then push the lever about half way down and start riding immediately. no stationary warm-up. after a few hundred meters i push the lever fully down to "choke off" and keep revs up if idling, by opening the throttle a bit.

[jonda500]

I like to start mine before putting my helmet and gloves on - first I kick it over a few times with the key off, full choke and the throttle held open (it's damn cold here atm), then start it with full choke no throttle and use the throttle friction screw to hold it just above idle, then back the choke off a tiny bit, - while I'm putting on my helmet the revs come up a bit so I adjust the throttle down a bit, put on my gloves, ride it out to the driveway, set throttle to fast idle again, shut the shed and the gate, then release the throttle friction screw, choke off and ready to go - it will idle at this point, but only just!
John

[Stev-o]

personally, i start up at full choke then push the lever about half way down and start riding...

+1

[Deltarider]

I like to start mine before putting my helmet and gloves on. When it's been more than a week, I first kick it over a few times with the ignition off, full choke and the throttle open, then start it with full choke some throttle (I use the idle adjust screw for this). Almost immediately after start I can press down the chokelever again, engine now runs about 2500 rpm and as it wants to increase its rpm, I slowly decrease the idle adjuster so it runs between 1500 and 2000.
Now comes the tricky part. I put on my helmet and gloves and vaguely I realise I've forgotten something but what: Ahhh... the balaclava, I need it to not catch a cold. Where is it, ahhh there is it. I lift my helmet, undo my gloves, pull the balaclava over my head and put on the helmet again. Where are my gloves? Ahh, there are my gloves, they must have fallen of the bike. Ready. Not quite. I've forgotten the earplugs and I need them to not become deaf. I lift my helmet again, pull the balaclava from my head and try to put in the earplugs with gloves on. Won't work. I undo my gloves. I put in the earplugs. I pull the balaclava back over my head, I want to put on my gloves, where are they? They have not fallen from the bike this time, where are they now? Ahhh, I had put them inside my helmet. I put my gloves on and put my helmet on. I'm almost there but I didn't follow the right order. In order to tighten the helmetstrap right, I'd better undo the gloves again. Áh... that's better. Now the gloves. Damn only one glove, where's the other? It can't be inside the helmet now. Ah, there it is, it must have fallen from the bike. Gee, it is dark here, ahhh... the sunvisor has come down. I try to bring it back up using the knob on the right side of the helmet, a bit difficult wearing gloves but I manage after I've remembered the knob is actually on the left side. In the meanwile a mist has built on the inside of my visor. I manage ro raise the main visor with gloves on but now the sunvisor comes down again. Never mind. I'm almost there. I mount the bike and ride the twenty meters towards and then on the slope where the detector is that should read the tagcard in my pocket. Should. It doesn't. What the &@#@$@@!! I let the bike roll back from the slope and kill the engine. The phonenumber of the company that can open the garagedoor from distance is on the panel in the wall. I lift my helmet, remove my balaclava and earplugs and fish my phone out of my pocket. Now I don't know if you've ever tried to use your phone with gloves on... The woman's voice at the other end says she will open the door for me and the same instant the door starts to open and I realise I have to act very quick now because the door will only be open for some 15 seconds. I manage to put on the helmet and gloves and restart the bike. No time to loose now. I take the slope and just before the door tries to behead me, I'm out. What a great feeling! When I leave town and start my favourite twisty, the loud noise from the riding wind tells me I must have forgotten the earplugs. I must have put them in the balaclava that probably lies somewhere on the garagefloor. Never mind. I enjoy my ride and when after an hour or two I return to the garage I detect my balaclava on the garagefloor. It looks dirty and I suspect it has been run over by one or more of my neighbours. When I want to undo my helmetstrap, I can't find it only to find out I never fastened it again after I made that call to have the garagedoor opened.
Recently I receive compliments of friends that say I look in such good shape and all and I tell them my secret: I've picked up cycling again.

[flybox1]

personally, i start up at full choke then push the lever about half way down and start riding...

+1

+2
my '74 550 was full choke and no throttle at start, and almost immediately after start the choke needed to be taken off.

[TwoTired]

Delta's bike has 649a carbs and an extra choke plate restrictor on top of his air box.  His carbs are jetted to compensate for that.  Runs way too lean without the restrictor.
If you have a USA type model 550 I warn readers not to adopt his operating practices, which are quite literally foreign.

I've been using manual chokes on vehicles since the 60s.  They are literally nothing new.  My 37 chevy had a manual choke knob AND a thottle knob to pull on the dash for cold operations.  Both were manipulated on the way as needed during warm up.

You do not want to flog the motor when the oil is cold.  But, it takes so little power to make the bike roll, it is unnecessary to warm it stationary.  Just keep the RPMs low, like below 4-5000 for the first mile -ish.

Most 550s don't have that throttle friction lock found on early Models.  Nice to have, if you do have it, though. I wonder why Honda discontinued it?

I've commuted with the 550 since 1975.  Warm ups extend commute time, which I feel warrants driving during warm up.  On-the-roll cold operation never hurt the engine in my personal experience with USA model 550s.

Imagine needing to warm up all the internal combustion engines on the planet before rolling out.  Preposterous.  It just isn't done, apart from the far superior Dutch, apparently.
 I do warm ups on the airplane, of course. (Air cooled four cylinder.) Because full power is needed for take off.  Taxi when cold is routine, though.  But, when the oil temp goes green, off I go.

So, believe whatever lunatic you wish to from the internet.  It's all free advice and some of it is worth just that.  Pity, that this forum used to be a really good source of quality info, now denigrated by such a small contingent.

Welcome to modern times and the open exchange of misinformation based on human emotional whimsy, rather than science and facts based on physics, (or proven reliable sources).
Reminds me of just why I ignored this forum for so long.

Cheers,

[Deltarider]

Here's the Owner's Manual for the CB550K
http://manuals.sohc4.net/cb550/owners_manual/OM55074.pdf
On p. 22 we read: When the choke lever is down (A) (normal driving position), the chokes are fully open. When the choke lever is up (B), the chokes are fully closed (cold engine starting position).
On p.27 we read:
6. after the engine starts, operate at approximately 2.000 rpm until the engine will respond to the throttle with the chokes open.
IMO it all speaks for itself. On p. 22 there is no mentioning of 'abnormal' driving positions nor 'half choke' or 'gradually closing' nor is it on p. 27. If you interpretate 'operate' on p.27 as 'ride', I wonder how you'd maintain 2.000 rpm. You'd be in danger and a hazard on the road. To me it's clear: Honda obviously intented you to have both hands at the handlebars at all times. Have a look how well the back then much praised switches were designed. All for safety. If you, riding a CB500/550, would not feel safe to lift a hand from the handlebars, guess what, you don't have to. Everything is under control with both hands at the bars. All the other actions like adjusting the mirrors and operating the choke lever are supposed to be completed before departure. You're not in a car, you're on a twowheeler that needs to be well balanced at all times. That we deviate from this, is another story. Nevertheless, do what you like.
The airduct that was on the models for some European countries, does not necessarily act as a restrictor and it certainly doesn't on the CB500. It's been tested not only by me but also by several Germans. We all came to the same conclusion. In original condition (4-4, OEM airfilter with cover and #78 main jets) and run on our gas, performance was best. All that tried without that cover and with #100 main jets, returned to stock. The difference in the rest of the carb settings (airscrew, needle height) probably has to do with it. Again, these were unmodified stock CB500s. BTW, I can't imagine how this cover could ever be restricting at lower rpm when on the dyno my 500 with cover and #78 main jets reached even it's theoretical topspeed of 185 km/h (see below). Now that's a lab condition with no riding wind. Testers in the Netherlands and Germany reached 179 km/h on the road. The airbox cover is believed to be a German manditory to reduce the intake noise to a legal level. It doubles as an useful shield against the ingress of water. Restriction is ofcourse formed by the carbs mouths diameter, the carbslides and eventual the chokeflaps. Just recently out of curiosity, I did a test at lower rpms with the cover as well the airfilter element temporarily removed. No change in rpm. No wonder, it is the slides that restrict, not the airbox, cover or not.

[TwoTired]

It defies all the laws of physics to expect the same or more power from less oxygen delivered to an internal combustion engine.
 An intake choke physically restricts oxygen delivery, anywhere it exists in the intake duct.
It doesn't matter what fudged or mis-labled charts, graphs, and opinions of uneducated, biased persons are presented here, regardless of their nationality.

Octane combustion is a chemical process and is pretty well known in the scientific community:
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O

Note the essential ingredient O2 in the process.  Nearly every Internal Combustion hop up in history involves getting more air (oxygen) into the combustion chamber in order to pair it with more hydrocarbons to yield increased power output.  Less inlet air restriction, velocity stacks, larger air filter area, ram air, turbos, superchargers, have all been key players, and all function to increase O2 delivery to the combustion chamber.

NASCAR dictates restrictor plates in the induction path for the expressed purpose of limiting and equalizing horsepower among contestants.  It is very effective at limiting speeds.
https://en.wikipedia.org/wiki/Restrictor_plate

To cling to the notion that restricting air delivery has no impact on engine power availability, is blind folly, or an overt attempt to corrupt reader's understanding of how things actually work in the real world without regard to rational thought processes, or scientific understanding.

Magazine articles are not required to adhere to the scientific process, only to promote sales of more magazine articles by appeasing the reader's psyche.

You, as a reader, require oxygen to function.  Do you think you could work harder with less oxygen available to you?  Try climbing a mountain.

Finally, putting a restrictor plate at the intake duct entrance modifies the vacuum profile inside the entire intake duct, including the carbs.  All behavior or fuel metering orifices, must be altered to supply the motor with equitable ratios. A crankcase breather system connected to the intake tract would also experience more drastic air flows due to the increase suction.
Such behavior is in no way representative of all the carbs in the USA (and most of the world).  To take your tuning and operation queues from such a dissimilar model, is ill advised, at best.

If, however, you have 649A carbs, then there is some merit to wrote, mindless following, and do operate with that inlet restrictor plate and filter box. I'll watch for you in my rear view mirror, should you escape countries where they were mandated by political interests.

Oh, and I will continue to use partial choke while driving whenever necessary.  I'm smart enough and educated enough to know when it is appropriate.

Works for me!

[robvangulik]

Octane combustion?