GT 550 blowing fuses

General discussion about Street two-stroke Suzuki motorcycles.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: GT 550 blowing fuses

Post by jabcb »

Fully charge the battery. Will make test voltages easier to interpret.

Starter wouldn't spin too energetically if the battery voltage is only 12.05V. Did you use the starter?

Your multimeter might be reading low. As a test you could check the voltage of your car's battery & with the car running.

How long did it take to blow the fuse? Could be time related.
Did you have the lights on?

Wiring diagrams on SmokeRiders website: http://smokeriders.com/Technical/wiring ... grams.html" onclick="window.open(this.href);return false;
Look at red wires from battery & rectifier:
1) for GT750 fuse is shown to be downstream of battery & rectifier
2) for GT380 & GT550 fuse is shown to be downstream of battery but alternator is unfused

I have GT380, GT550 & GT750 owners manuals. Wiring diagrams in these manuals show the fuse to be downstream of the battery but the alternator is unfused

This adds an additional complication that you can't completely trust the wiring diagram.

Check the resistances I mentioned with:
1) battery disconnected & fuse removed
2) battery disconnected
3) battery disconnected & rectifier disconnected

Check voltages running with and without lights.

Sorry if I ask for too many tests. Doing remote diagnostics like this makes it difficult to figure out exactly what to ask for.

Maybe someone else has some testing ideas that will make diagnostics a little less tedious.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
jmcgill89
On the main road
Posts: 110
Joined: Wed Oct 27, 2010 6:55 am

Re: GT 550 blowing fuses

Post by jmcgill89 »

That's interesting....

The starter spun very well when the voltage was 12.05 V....

I'm going to try things again this afternoon....now that I have those two wire clusters in the correct places.

Perhaps my meter isn't registering correctly.

The fuse wasn't time related. I ran it at 4500-5000 RPMS for 15 seconds and it didn't blow, but when I was RIDING it, and wound it up like that it blew in 3 seconds.
1974 Suzuki GT550 - Smoke Generator
2010 Harley-Davidson FXDB - The Commuter
1994 Honda Nighthawk 250 - Almost Run Over
jmcgill89
On the main road
Posts: 110
Joined: Wed Oct 27, 2010 6:55 am

Re: GT 550 blowing fuses UPDATE

Post by jmcgill89 »

I took the bike out again today after fixing that wire mixup.

The battery at 5000 RPMS showed about 14.7 or so volts and it increased as throttle was applied.

Definitely better than yesterday.

I took it out for a ride, and I actually got it into 4th gear, and it was just fine. I revved it up to 5k while accelerating, and it didn't die...it didn't miss either. Smoked like a demon, but it always does that. (and it's running premix along with the oil pump now).

When I got home, I checked the wires for heat and they were not hot.

I'm going to ride it for a longer distance tomorrow, but, I'm cautiously optimistic.
1974 Suzuki GT550 - Smoke Generator
2010 Harley-Davidson FXDB - The Commuter
1994 Honda Nighthawk 250 - Almost Run Over
User avatar
oldjapanesebikes
Moto GP
Posts: 3229
Joined: Sat Feb 07, 2009 12:43 am
Country: Canada
Suzuki 2-Strokes: GT750(Jx3,L,M,A,B),T500
Location: Ontario
Contact:

Re: GT 550 blowing fuses

Post by oldjapanesebikes »

jabcb wrote:Maybe someone else has some testing ideas that will make diagnostics a little less tedious.
jabcb - you clearly know more than most about electrical testing and troubleshooting - I've been reading through several of your posts and find your suggestions quite useful and also easy to follow. Something for you to consider might be for you to compile them into one post under a new topic ('Electrical Troubleshooting Tips' perhaps) in the 'Repairs' section which then could be made a 'sticky' for permanent reference. I think then we would all benefit. 8)
Ian

If at first you don't succeed, just get a bigger hammer !
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: GT 550 blowing fuses

Post by Suzsmokeyallan »

I have a question, when you mixed up the two connectors did you notice the wire colours on each side of each cavity not matching?
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
jmcgill89
On the main road
Posts: 110
Joined: Wed Oct 27, 2010 6:55 am

Re: GT 550 blowing fuses

Post by jmcgill89 »

Where I got screwed up was with the colors of the connectors. I mistakenly put blue with blue and didn't double check. I feel like a real dope.
1974 Suzuki GT550 - Smoke Generator
2010 Harley-Davidson FXDB - The Commuter
1994 Honda Nighthawk 250 - Almost Run Over
User avatar
Suzsmokeyallan
Moto GP
Posts: 4326
Joined: Fri Oct 24, 2008 9:11 am
Location: Mostly Barbados, sometimes Florida and western Canada
Contact:

Re: GT 550 blowing fuses

Post by Suzsmokeyallan »

I feel like a real dope.
Nah,,, its mistake someone can make, but I know you certainly wont make that one again. The Oregon regulator has a 'pot' on the base of it that varies the output within a range of 0.5 volt.
Usually the middle position of the screw slot equally from full left to full right is the stock setting, just in case you are wondering.
Two strokes, its just that simple.

69 Suz U70
69 Suz T500
72 Suz GT750 cafe
74 Suz TS250
74 Suz GTXVR project
75 Suz RE5
75 Suz GT750
76 Suz TS400
76 Suz GT750
81 Suz GSX1100
86 Suz RG500x2
88 Hon CR500
93 Hon CBR900RR
98 Suz GSF1200x3
15 Kaw Ninja H2
Madbuffalo
To the on ramp
Posts: 463
Joined: Thu Feb 17, 2011 8:55 pm
Country: USA
Suzuki 2-Strokes: GT750
Location: Grand Rapids, Michigan, USA

Re: GT 550 blowing fuses

Post by Madbuffalo »

oldjapanesebikes wrote:
jabcb wrote:Maybe someone else has some testing ideas that will make diagnostics a little less tedious.
jabcb - you clearly know more than most about electrical testing and troubleshooting - I've been reading through several of your posts and find your suggestions quite useful and also easy to follow. Something for you to consider might be for you to compile them into one post under a new topic ('Electrical Troubleshooting Tips' perhaps) in the 'Repairs' section which then could be made a 'sticky' for permanent reference. I think then we would all benefit. 8)
I'll second that. :up: My bike wouldn't be running right now if it weren't for jabcb's direction.
No really... it's supposed to smoke.

1974 Suzuki Nomad 340
1975 Suzuki GT750 Waterbuffalo
2018 Kawasaki Z900rs
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: GT 550 blowing fuses

Post by jabcb »

jmcgill89 wrote:I'm going to ride it for a longer distance tomorrow, but, I'm cautiously optimistic.
Good luck.

Oldjapanesebikes & madbuffalo, I agree that a 'sticky' electrical tips is a good idea. Doesn't take very long for a thread to be buried too deep for people to find. A good task for a rainy day with nothing to do.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
Post Reply