Honda 77 cb550f electrical issues | GTAMotorcycle.com

Honda 77 cb550f electrical issues

Kyle_Bleiman

Active member
Hi everyone,

I first introduced myself in a different section of this forum but the thread has sort of turned into technical questions so I thought it may make more sense to post my issues in this section. The thread can be seen here - http://www.gtamotorcycle.com/vbforu...-New-Rider-Excited-to-finally-be-able-to-ride

Basically I was driving the bike today and it just died on me. Opened the left side cover and it looks like the 15amp fuse blew. Thats's the very right fuse of the 3 fuses that were there. Walked to a hardware store and picked up a few more fuses just in case it died again. Placed one in and the bike started fine. Got about 50ft and it blew again. 2nd fuse got me a bit further and 3rd one got me about half way home before I had to call CAA and have the bike towed home. What a day! I feel like I've had horrible luck with this bike - only had it 2 weeks and already I've had to replace the battery and now this.

Anyone have any idea what this may be? I am a brand new rider so I don't know much about bikes or how they are built. The simpler the answer if possible the better.

Thanks
 
For starters list all the aftermarket electricals that was replaced. Add up all the wattages and see how many amps your bike is pulling lets start with that.

Then from there check all connections and make sure there is no loose/exposed wire anywhere.

Lastly and hopefully not, your reg/rec may be pooched.
 
Last edited:
Not even sure where to start here. As far as aftermarket electrical there wasn't a ton done. Both original gauges were removed and we added 1 guage. We also added a USB charger which has been disconnected since I got the bike as we had battery issues and we thought this may have been draining the battery. We replaced all 4 signal lights with new lights and the rear brake light with a new light as well. I think that's everything.

As far as checking out the wiring where do I begin and what am I looking for? The guy who built the bike said to take apart the starter as he has a feeling something there may be causing the issue?
 
my relatively uniformed guess is a problem with the stator or regulator/rectifier. Google for how to test them.

What gauge did you add?
 
Could be your reg not doing its job. But you can put a 20a like me. But i had some mods done that requires more amps n
 
That could work, but you need to be careful replacing fuses with bigger ones. Fuses are there for a purpose. They are the weak point in a circuit that self destruct to prevent more expensive and important things from being damaged. You really need to know how much current is actually needed and if the wires attached are capable of handling it. If you're not sure what you're doing, you risk damaging other components or even causing a fire.
 
My guess would be either:

1) There is a short somewhere. An example of this could be a loose wire. As you're riding it bounces around and eventually comes into contact with the frame. The battery is now connected + to - through this short. If there wasn't a fuse to break the connection your battery would be damaged.

2) The circuit is legitimately drawing too much current. I don't know if your builder underestimated how much would be drawn, or someone added too many extra accessories onto the stock wiring, but it's drawing more than it can handle. An example of what might happen is someone rides around and everything is fine because they're drawing just under what the circuit can handle. Then after a while the bike heats up and the fan tries to turn on, pushing the circuit over the limit. If there was no fuse and the wire wasn't big enough to handle the current, it could get really hot possibly melting or burning something.
 
Last edited:
My guess would be either:

1) There is a short somewhere. An example of this could be a loose wire. As you're riding it bounces around and eventually comes into contact with the frame. The battery is now connected + to - through this short. If there wasn't a fuse to break the connection your battery would be damaged.

2) The circuit is legitimately drawing too much current. I don't know if your builder underestimated how much would be drawn, or someone added too many extra accessories onto the stock wiring, but it's drawing more than it can handle. An example of what might happen is someone rides around and everything is fine because they're drawing just under what the circuit can handle. Then after a while the bike heats up and the fan tries to turn on, pushing the circuit over the limit. If there was no fuse and the wire wasn't big enough to handle the current, it could get really hot possibly melting or burning something.

These are air cooled bikes. 20a is safe for the wires as the wires on that bike stock is 16. I have to double check what the rec/reg Imax is. 20A is safe to use however id suggest you checking all of your wires to make sure theres no short.
 
These are air cooled bikes. 20a is safe for the wires as the wires on that bike stock is 16. I have to double check what the rec/reg Imax is. 20A is safe to use however id suggest you checking all of your wires to make sure theres no short.
Yes, the fan was just an example. It sounds like you know enough to recommend a safe size, which is what I was trying to get at. Its still curious if a 15 amp fuse is stock its not enough to handle the load. Makes me think something somewhere is not as it should be.
 
On 37 year old bikes anything can happen. A wire might be frayed, contact the frame to ground and pop your fuse. Dirt, crud, oxidization, all these things come into play. Leave nothing to chance.

Buy a Clymers, other service manual, or at minimum get the electrical schematic for your bike. Buy a multimeter ($10 Crappy Tire digital) and learn how to use it for electrical continuity. Check every connector, length of wire, switch, solder joint, electrical socket, everything. Use your multimeter as proof. Do a thorough job and clean connections as you go. Once you clean and check a connection, mark it off your electrical schematic. This way you are sure the nervous system of your bike is sound and you will be rewarded for years to come. While this painstaking testing will take a lot of time, your bike will be more reliable.

If you are unwilling to learn some simple electrics, like putting your USB charger on a relay, then you have no business buying an old bike. Old bikes are cheap, yes, but they require you to learn new skills because maintenance is crucial so that you are not left stranded. Old bikes are often hacked to a hair of their lives by backyard mechanics, with problems passed down to unsuspecting new owners. There are lots of sites available and lots of people here willing to help you. Are you up to the task of learning?
 
Wow lots of comments, thank you. I have to be honest. At this point based on where we are in the season I just want the bike fixed asap so I can at least get some riding in before the season is over. After that I have no issue trying to learn as much as I can about the bike and it sounds like I should start by picking up a service manual and giving it a good read.

My issue is the guy who built the bike is over 3 hours away. I found someone else through a recommend but I'd have to get the bike to him (I don't have a way to transport the bike currently) and he even said based on the fact he didn't build the bike he thinks the guy who built it could potentially solve this electrical issue much faster.

Not sure what to do at this point but as each day passes I feel like I'm missing out.
 
What you need is a place that understands 30 year old bikes.....

you have a Honda, this is a Suzuki site - http://www.thegsresources.com/_forum/index.php but I am sure if you sign up, post a question in the right area, you will get some good feed back

and number 7 in this....

Top 10 Newbie Mistakes

1A) (NEW) Trying to diagnose running problems on a bike with an unknown maintenance history is an exercise in futility until a baseline is established through proper maintenance. Things like clean carbs, properly adjusted valves, sealed intake system (airbox, carb boots), a clean gas tank (no rust), and a properly functioning petcock are 100% mandatory for the bike to run properly. It's best to perform all the bikes maintenance when you first get the bike, and then if problems show up you will know what the problem is not.

1B) Incomplete carb cleaning. A proper carb cleaning requires a full tear down, soaking the parts in carb dip, and reassembly with fresh O-rings (cycleorings.com). Pilot jets, choke tubes, and pilot circuit passages in particular need a proper cleaning before the bike will run right. Even if the bike seems to run right, if the O-rings are original they are sure to be hard and brittle thus problems could be right around the corner. This is a link to a carb tutorial that you may find useful... http://www.mtsac.edu/~cliff/storage/...d_Tutorial.pdf

2) Not replacing the intake boot O-rings. The classic "hanging idle" (or idle speed that increases on it's own as the bike warms up) is often traced to this simple fix since air gets sucked past the old O-rings and into the engine causing a lean condition. Most GS bikes have these O-ring, but not the 2nd generation 750 or 1100E family. While you are at it, make sure the entire airbox system is 100% sealed, since drawing false air into the system will increase running temperatures and make the bike run poorly.

3) Not adjusting the valves. The valves tighten with mileage, and once all the clearance is gone the valves hang open and burn. Not good. If you wait for your bike to misbehave before performing this critical maintenance, you may damage the engine. If your valves have no clearance, you will need a thin checking shim in order to properly calculate the needed shims for your engine.

4) Trying to run the bike without the airbox...or installing pods, or a header, w/o rejetting. The air/fuel ratio will be drastically lean, which will not only cause running problems, but likely damage the engine too by causing it to run hot. Installing a free flowing exhaust will likewise change the jetting requirements, but not as drastically as pods.

5) Ordering "carb kits" full of inferior aftermarket jets. A new O-ring kit from cycleorings.com is all that's necessary most of the time. Get some new float bowl gaskets and pilot jet plugs if necessary from a place like Z1 Enterprises to supplement the O-ring kit.

6) Trying to clean out the brake system full of brown gunky fluid by flushing the system. If the fluid is dark and brown the only way to clean the system is a full tear down and clean out otherwise chunks will remain behind in the system. While your at it the old rubber brake lines should be changed. Suzuki call for replacing the lines every 2 years, so if your bike still has the originals you are 28 years overdue.
tongue.png
The old lines will lead to spongy brake lever feel and contaminate the fresh fluid you just installed.

7) Waiting for the charging system to fail, instead of cleaning up the old wiring. Many a battery have been boiled dry after the grounds corrode. Running a dedicated ground to the battery, or a solid frame attachment point, is strongly advised. Suzuki also botched the stator wiring by routing one leg up to the now discontinued head lamp switch. This needless wire path often overheats and damages the harness in the process. Do yourself a favor and rewire your charging system: run the stator wires directly into the R/R, make sure your R/R has a solid battery or frame ground point, and run the positive (power) R/R output either straight to the battery (with 20A fuse in-line) or though the regular fuse block after you check for resistance in the circuit and repair as needed.

8) Using the wrong oil and/or gasoline. Auto oils have less zinc and phosphorus (high pressure additives) than they used to since the EPA has mandated reductions to protect catalytic converters. Motorcycle oils are fine but expensive, and even motorcycle oil has reduced additives these days. Diesel engine oil is cheap and contains lots of high pressure additives appropriate for our engines. Shell Rotella oil is even certified for use with wet clutches if that makes you more comfortable, although just about any diesel oil is fine. As for fuel, Suzuki calls for use of Regular gas. Using Premium provides no positive benefits for your bike and is more expensive.

9) Search out the information about your upcoming wrenching tasks before going off unprepared and possibly damaging something. Search using "Advanced Search" and then click "Titles Only" to quickly hone in on the topic at hand. Almost every possible question a newbie could ask have already been answered. For example: there are tons of threads on how to avoid broken exhaust bolts and float posts. Sadly, most newbies learn these tricks AFTER they damage their bike.

10) Buying a 30 year old motorcycle because it was cheap without any mechanical knowledge and no interest in learning. Paying a shop to work on your 30 year old motorcycle is not advised unless you have lots of money to spend and know for a fact that they are trustworthy.





This might help you out as well

http://www.thegsresources.com/_foru...rging-System-QUICK-TEST&p=1272192#post1272192
 
Last edited:
Where do you live OP? I may be able to swing by sometime this week or weekend. To check it out.
 
Join sohc4.net Ask away there. There's tons of guys on there that know their stuff.

pictures of your system would help a lot.
 
So my friend just came by and it looks like the problem is fixed. There were 2 wires that came loose from the rear light that looked like they burnt and were stuck together. He re-wired them and it seemed to do the trick. I think this happened when I tried to take my rear fender and make it sit higher - probably a wire came loose and caused the issue.

Thanks for all the help everyone.
 

Back
Top Bottom