Maybe its a short?

[Cowichan550]

I have a 1981 550 t. It sat for a long time outdoors. I recently got the engine unseized by pouring some penetrant into te cylinders and turning the crank with a wrench. It eventually ran after cleaning the carbs.
Now I have been experiencing the top (15 amp) and second to top (10 amp) fuses burning out. My dad suggests just replacing the 15 amp with a 20 or 30 amp fuse and see what happens. Is this potentially dangerous to the bike?
If it is what do i do to stop the fuse from burning out?

[Steve]

If you simply keep replacing your fuses with heavier fuses, you will soo find out which wire in the harness can not handle the extra load.

DO NOT PUT IN HEAVIER FUSES.

Not sure what you are calling "top", because, as I know them, the "top" slot should have a 10A fuse in it. Does your fuse panel have five fuses and a pair of screw terminals? If so, the fuse farthest away f rom the screws is the one I have usually seen on "top".

So, going on that assumption, here is what the fuses power:
LIGHTS - including the headlight, tail light and instrument lights
SIGNALS - including turn signals, brake lights, horn and oil pressure warning light
IGNITION - including coils and ignitor
MAIN - powers the entire bike until the engine is running and the charging system takes over
AUX - powers the + screw terminal.

The MAIN fuse should be a 15A, all the rest should be a 10A fuse.


Now that you know what is downstream from the fuse, you should be able to narrow down your search.

.

[SVSooke]

Depends on the fuse box Steve.The 78 1000 box I have in front of me has the main on top.Headlight is the next one..All so have an 83 750 blade style box here I'm planning to replace the older box with,that one has the pattern you are thinking of.Cowichan,you have got to find the problem.Putting in bigger fuses is not the answer.
Welcome to GSR,nice to see another member from VI.

[Steve]

Depends on the fuse box Steve.The 78 1000 box I have in front of me has the main on top.

Yes, I realize there are differences. Before '80, some of the smaller bikes only had one fuse. Some of the larger bikes had a panel of four, with the AUX fuse by itself. Most of the ones I have seen from '80 on have had the five-fuse panel as I have described.

Worst-possible case, you start from scratch. Pull all the fuses. One side of one fuse slot will be HOT (electrically), that is your MAIN fuse. Put that one in, one side of another slot will become HOT. That is your AUX fuse. Now turn the key on, one side of the other three slots will become HOT. Put a fuse in one of them, see whether you have lights, signals or ignition. Repeat with the other two.

.

[Killer2600]

When do the fuses "burn out" or as I say "blow"? When the bike has started? If they blow when the bike is running but not with the key on and motor off I'd check the battery voltage while the bike was running, the charging system might be messed up and putting out high voltage that can blow fuses, break stuff, and even kill or shorten the life of a battery.

[OldVet66]

Also consider the overall shape of the fuse box itself. If the contacts are corroded, or have been, the fuse box itself can cause the fuses to blow. It's most likely a combination of that and poor connections throughout the wiring harness where the cables plug together. That's why it is so important to inspect all connections, clean or replace as necessary, and check the major plugs to see if they are getting hot when the bike is running. The connection points should stay cool, otherwise there is a high contact resistance that, accumulating from a bunch of bad connections, can cause the circuit to pull too much load and blow fuses. A short will immediately blow the fuse. The switches and grounds should also be cleaned and everything coated with dielectric grease to help prevent further problems. The switches have small parts and springs, so it might not be a bad idea to work on them in a clear plastic bag so irreplaceable small parts don't get lost or go zinging off into who knows where. Even the bulb sockets and the headlight plug should be checked.

[BassCliff]

Greetings and Salutations!!

Hi Mr. Cowichan550,

Start by inspecting and cleaning every electrical connection and ground on the entire wiring harness. You'll find tips in the electrical section of my little website. Please do not over-fuse.

Now let me dump a TON of information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. This is what NOT to do: Top 10 Newbie Mistakes. Now let me roll out the welcome mat for you...



Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Cowichan550]

First of all thanks for all the quick responses. Second of all, thanks for the warm welcome.
I started the bike and held a voltmeter on the battery and it only read 12 volts. The bike is still running a little rough, but I got the rpms up enough that it should have read 14 so its definitely not charging. I'm gonna assume that the r&r is toast and that I should get a new one before going any further?
Any suggestions?
Oh, btw, I tested the voltage because it WAS blowing the fuses while running only I think. The fuse box and surrounding connections were all good. Very little to no corrosion.
Also, very cool to see fellow Islanders and fellow believers all in one place.
Thanks again.

[Steve]

. I'm gonna assume that the r&r is toast and that I should get a new one before going any further?
Any suggestions?

I would suggest that you stop assuming and start testing.

A few minutes with your meter and the Stator Papers or Posplayr's Quick Test will help you determine what you need to fix or replace.

.

[duaneage]

When do the fuses "burn out" or as I say "blow"? When the bike has started? If they blow when the bike is running but not with the key on and motor off I'd check the battery voltage while the bike was running, the charging system might be messed up and putting out high voltage that can blow fuses, break stuff, and even kill or shorten the life of a battery.

A bad RR will short the main fuse as soon as the AC voltage from the stator hits it. Basically, the regulator SCR activates and shorts out.
I saw this happen on TheBigRed's 550T and it was verified to be the RR.

[Killer2600]

A bad RR will short the main fuse as soon as the AC voltage from the stator hits it. Basically, the regulator SCR activates and shorts out.
I saw this happen on TheBigRed's 550T and it was verified to be the RR.

Did the bike continue to run? Failure as you defined is suspect, the SCR's job is to shunt or "short" to ground any and all high voltage.

Either way I covered the basics, if the fuses only blow when the bike is running the charging system is suspect and your problem likely isn't a hard short in the wiring. I won't go into further detail because my listed join date is recent and as such I've found my expertise and/or methods aren't appreciated much so why waste the time.

[posplayr]

Did the bike continue to run? Failure as you defined is suspect, the SCR's job is to shunt or "short" to ground any and all high voltage.

Either way I covered the basics, if the fuses only blow when the bike is running the charging system is suspect and your problem likely isn't a hard short in the wiring. I won't go into further detail because my listed join date is recent and as such I've found my expertise and/or methods aren't appreciated much so why waste the time.

This is a classic misunderstanding of what the R/R is doing when SHUNTING.

The SCR shorts (shunts) ACROSS the stator winding so that (at peak of the relative phase) current flows only through the stator and not out of the R/R (on either the + or - wires). There is no current through the ground i.e. (the R/R(-) ) when the SCR is shorted.

The current paths are indicated in the attached page of the GS1100E manual. There is no current into or out of point Circle D from ground.

[posplayr]

A bad RR will short the main fuse as soon as the AC voltage from the stator hits it. Basically, the regulator SCR activates and shorts out.
I saw this happen on TheBigRed's 550T and it was verified to be the RR.

While an SCR should be expected to fail in a shorted mode, I don't see where that would cause a high output from the stator winding to the R/R output. The R/R would be in an always shunting mode (i.e. no output from R/R).

http://www.ssousa.com/appnote050.asp

I can only see how a rare (1 in 10) SCR failed open and the R/R could not regulate allowing higher "unregulated" voltage to get to R/R(+) and on to rest of the electrical. Most of this current would not be going through the battery though so not sure it would blow a 15 amp MAIN fuse between R/R (+) and the battery (+)

If a 15 amp main fuse is blowing it could also be (or more likely be) the Regulator output stage internally shorting R/R(+) to R/R(-) and thereby shorting across the battery which would get a lot of current draw from the battery.

I think there is an resistance test between R/(+) and R/R(-) in the stator pages..... Doesn't seem to be one.

EDIT 4/21/2012:
A shorted R/R output stage would blow a fuse anytime the R/R was connected to the battery including when the KEY IS OFF. This is NOT the case here.

Since the fuse is blowing when the bike is started, it is most likely a rare failure = FAILED OPEN SHUNT SCR where the R/R can rectify but not regulate.

The more common failure = FAILED SHORT SHUNT SCR would not blow a fuse but would burn the stator/R/R and the wiring between them depending upon how long and how high of RPM the bike is run in this condition.

[duaneage]

I watched a RR blow the main fuse on a GS550T as soon as the engine started. I replaced the RR and it never had the problem again.
Your free to try this as a solution, or examine it as much as you want.

[Killer2600]

This is a classic misunderstanding of what the R/R is doing when SHUNTING.

The SCR shorts (shunts) ACROSS the stator winding so that (at peak of the relative phase) current flows only through the stator and not out of the R/R (on either the + or - wires). There is no current through the ground i.e. (the R/R(-) ) when the SCR is shorted.

The current paths are indicated in the attached page of the GS1100E manual. There is no current into or out of point Circle D from ground.

Nothing is ever perfect enough for you and you over analyze words until you lose sight of the meaning for them.

Do this, take a look at your little R/R schematic. See the cathode on the SCR, see where the trace goes to a frame ground symbol, see the battery negative, see where it also goes to a frame ground. Shunting or shorting to ground seems an accurate enough description in my book and would apply to separate rectifier/regulator circuit where as yours is limited to a single design.