GT 550 blowing fuses

[Coyote]

There is another ground. Part# 48528-78200. It runs from one of the coil mounting bolts to the forward most center shroud screw. I have a shiney new one in oem packaging here if you need it. I'm not saying this is a fix, but Suzuki put it there for a reason.

[Suzsmokeyallan]

Oh I agree Coyote, the manufacturer puts parts on the bikes only if they deem it necessary. In this case anything to improve grounding is a good thing, especially in DC circuits where voltage drops along wires are an inherent flaw of the system.
However having said that, they missed this simple point in making the main circuits of a larger grade wire.
So as a simple update if you have the harness up for some restoration, just upgrading the red, orange and grey wires in the main circuit on these old systems to a larger size can offer less voltage drop along the distance.
I hate to say this,, ahem,,but Kawasaki did this on alot of their bikes of the same vintage as the GT to help improve the flow of current in the main circuits such as the ignition and headlamp.

[tz375]

There is another ground. Part# 48528-78200. It runs from one of the coil mounting bolts to the forward most center shroud screw. I have a shiney new one in oem packaging here if you need it. I'm not saying this is a fix, but Suzuki put it there for a reason.

I wondered where that was supposed to go. I have a couple left over from earlier builds........

[Suzsmokeyallan]

Richard, that is so not like you, what were you thinking.

[oldjapanesebikes]

There is another ground. Part# 48528-78200. It runs from one of the coil mounting bolts to the forward most center shroud screw. I have a shiney new one in oem packaging here if you need it. I'm not saying this is a fix, but Suzuki put it there for a reason.

I wondered where that was supposed to go. I have a couple left over from earlier builds........

[jmcgill89]

I will certainly check that when I get home.

[jmcgill89]

I do, indeed, have that forward ground coming from the coil area to the shroud.

Before I replace the regulator, I'm going to clean all the contacts where the wires go together. I was messing with it last night and found that my headlight was not tightened well at all, so I went back in there and made darned sure that all the mountings for the headlight and turn signals to the ears were very tight and secure.

Next I'm going to go one by one and pull the wires apart and reinstall them with contact cleaner.

After that (hopefully, I will have the starter clutch done by then) I will do the test to see if it's overcharging.

Hopefully I'll have some good news to report later this week, if things at work aren't too busy.

[jabcb]

Don't currently have a GT380 or GT550. If memory is correct, the shroud is not bolted to the head with metal to metal contact. Small insulating spacers are used around the bolts. This allows for some differential thermal expansion.

As a result of using the spacers, the shroud would be ungrounded. The grounding wire between the coil area and shroud is there to eliminate a large ungrounded chunk of metal near the ignition system.

Correction to my previous post... (sorry, should have read your post a little more closely)
Fuses have a resistance of around 0.05 ohms. They get hot when conducting current and burn out when conducting too much current. If a bad fuse holder or bad wiring near the fuse heats the fuse, then it won't take as much current to burn out the fuse. When the fuse burned out at 4,500 rpm it could have been the result of a modest, but still OK, increase in voltage.

Could have multiple problems. Since the tests are easy & quick to do, the resistance tests I mentioned, and voltage tests everyone mentioned are worth doing.

One possibility is that its running badly because of low voltage at the coils, the voltage is still low at 4,500 rpm, the fuse is blowing because its being heated, and a separate problem is causing low voltage.

Also, just moving the wiring near the fuse might make that problem go away or reappear. Might be the reason the second fuse burned out more quickly.

Somewhat unrelated thought...
Suzuki used two different alternators vendors for the GT380/GT550. The Kokusan alternator had modest output while the Denso alternator is about equivalent to the GT750 alternator. Both types are available on eBay.
See page 18 in: http://www.ozebook.com/compendium/suzi/suzidata1.htm

Haven't investigated to see if there are any issues when switching alternators. I would have expected people to snatch up the Denso alternators when they become available on eBay, but that doesn't seem to be the case.

[jmcgill89]

I plan to do all the tests once I get the starter clutch changed out (didn't have a 32MM socket last night).

I have to think that something about the electrical system caused the running problems AND the fuse blowing issues.....because I literally didin't touch anything else aside from those wires in the headlight.

We shall see.

[H2RICK]

Don't currently have a GT380 or GT550. If memory is correct, the shroud is not bolted to the head with metal to metal contact. Small insulating spacers are used around the bolts. This allows for some differential thermal expansion.

As a result of using the spacers, the shroud would be ungrounded. The grounding wire between the coil area and shroud is there to eliminate a large ungrounded chunk of metal near the ignition system.

I believe you're correct, jabcb. I seem to remember a service bulletin about that strap and its purpose being to eliminate RFI.

[jmcgill89]

Well, I got the starter clutch changed out, and the trans filled back up.

I also made the following changes:

Oregon parts regulator
new fuse (Ace Hardware one).
All ground wires tightened.

Started her up, and she fired right away...idled nicely even without the choke.

I took it for a spin, wound it up to about 5k RPM in second gear and the fuse blew.

So, I replaced the fuse and put the volt meter on the battery to see what the voltage was.....at 4500 RPMS (consistent), it was about 11.7 volts DC. At idle, it was about 11.63.

Now, I'm back where I started...blowing fuses.....this stinks.

[Cliff]

What's the battery voltage with the bike shut off? In order to trouble shoot this we have to know what the battery voltage is to start with. A fully charged battery should be around 12.5 volts. At 4500 RPM you should have from battery voltage to a max. of 14.5 volts. You only have 11.7 volts now at 4500 but what did you have before you started??
A quick check for shorts or blown fuses is to check the wires temperature! With the bike running feel the wiring. Any hot wires? Check the fuse holder itself. A corroded connector there will blow the fuse.
Good luck!!
Cliff.

[jmcgill89]

I went through the wires again.....I had mixed up two of the six wire connectors. Once I fixed the connectors and got the wires straight, I got the neutral light and cluster lights to work. I don't know, but this screwing up of the wires might have caused the problems.

I just went and tested the battery....12.05 volts.

[tz375]

It would be nice if that problem is now fixed with the latest changes. Those are odd results form that voltage test Almost sound like a shot regulator or a really bad battery ground.

Fully charged battery turned off should be over 12V. close to 13. Turn on the ignition and it should drop slightly. Fire it up and it should more or less hold its own at 2k and should be over 13 at 4k.

Your results don't sound right and point to a problem somewhere in the charging or grounding.

[jmcgill89]

In response to Cliff,

That was the weird thing....right after I blew the fuse that last time (my new blade styled fuse), Iwent and felt all the wires in that area....they were warm, but none were hot, and there was no sign of burning.

I'm really hoping that by fixing those crossed wires I'm going to get it running properly.