78 GS750 Starting trouble!

[gottogochop]

Okay, First, I'd like to start off by saying this looks like a great forum and I'm glad to be apart of it!

My problem started a few weeks back, I took my bike to work, (started fine), and when I went to start it up again, it wouldn't. (even when kicked.) after many attempts, I finally bumped started it.

On the ride back, I had to have choke fully open, or it would want to die. the headlight would dim and turn off completely at times...Scary when your on the highway at 4am!

The next day I go to see what the heck is up with my bike, I turn the ignition on, headlight too. I go to start it and the light trips out. so I'm thinking there is a short or a bad ground somewhere. I test the starter, it was fine, the manually lead me to believe it was a bad starter relay. So I bought a universal after market one. installed it. Bam, the bike starts up, seconds later a ground coming from the headlight goes up in smoke. I ended up removing it, looked like someone didn't know what the heck they were doing when they were re-wiring the bike! The bike starts one more time, runs rough for 5 minuets. I go to start it up one more time, the relay makes a super loud clicking sound, the starter works weakly and the bike doesn't start.

That's where I'm at now with it at the moment.

I should add, the battery good, and all connections are snug.

Sorry for the long post!

Thanks!

--Paul

[tom203]

Is this bike new to you? wiring on these old bikes can attack at any time, so best to doublecheck everything. Have you checked charging system out? Does this model have multiple fuses? of right size?

follow this link and poke around

http://members.dslextreme.com/users/bikecliff/

[btbarb]

If you know the wiring is wonky, this might help, here's a link to a color wiring diagram that member ValorSolo put together for your bike.

78 750 Color Wiring Diagram PDF

While you are verifying your wiring to the diagram, check your grounds, look for pinches, bad insulation, loose connectors.

[gottogochop]

Is this bike new to you? wiring on these old bikes can attack at any time, so best to doublecheck everything. Have you checked charging system out? Does this model have multiple fuses? of right size?

follow this link and poke around

http://members.dslextreme.com/users/bikecliff/

Yeah, the bike is new to me. I'll have to check about the fuses.

Thanks guys!

[Redman]

Paul,

welcome to GSR.

No need to appologize for long post. The info is good. Better than "doesnt start now, it did 3 days ago".

Smoked headlight ground wire sounds like a seperate problem from the other symptoms. You mean the ground wire in the headlight area? Or a ground wire comming out of the harness and connected to bike frame near the battery?

I suspect your other problems are maybe that charging system not working and then battery is going dead.

In your description of things you didnt state any battery voltage readings.
You have a volt meter? You have a 30+ year old bike, and its a 30+ year old Suzuki you will need a voltmeter (multimeter) from time to time.

You have a samll battery charger? Put the charger on it for a few hours, see if that makes a difference., and can get it started.
Check battery voltage with running at about 4000 rpm, should be upper 13s or low 14s, definatly higher than with engine off.

Tell us more what you find.

.
.

[gottogochop]

Paul,

welcome to GSR.

No need to appologize for long post. The info is good. Better than "doesnt start now, it did 3 days ago".

Smoked headlight ground wire sounds like a seperate problem from the other symptoms. You mean the ground wire in the headlight area? Or a ground wire comming out of the harness and connected to bike frame near the battery?

I suspect your other problems are maybe that charging system not working and then battery is going dead.

In your description of things you didnt state any battery voltage readings.
You have a volt meter? You have a 30+ year old bike, and its a 30+ year old Suzuki you will need a voltmeter (multimeter) from time to time.

You have a samll battery charger? Put the charger on it for a few hours, see if that makes a difference., and can get it started.
Check battery voltage with running at about 4000 rpm, should be upper 13s or low 14s, definatly higher than with engine off.

Tell us more what you find.

.
.

The ground wire was coming off a wire that was coming out of part of the wire harness from the head light, It looked like it didn't belong there. I removed it after it went up in smoke and the bike started up.

I took the battery to battery's plus and the guy said it was good.

I'll throw it on a charger one more time to see if anything changes.

what I don't understand is if the relay is good, and the starter is also, why isn't power being sent to the starter? I'm thinking that it has something to do with this aftermarket starter relay, I must have hooked something up wrong. I might try to buy an original relay and hook that up.

[terrylee]

Make sure the relay is grounded well, check to see if you get 12 volts to starter when pushing starter button. Might check starter button and make sure contacts are not corroded inside. Are you getting 12 volt from battery to relay connection? terrylee

[Canuck_gs]

If you know the wiring is wonky, this might help, here's a link to a color wiring diagram that member ValorSolo put together for your bike.

78 750 Color Wiring Diagram PDF

While you are verifying your wiring to the diagram, check your grounds, look for pinches, bad insulation, loose connectors.

Hi there! I'm new to the forum (still need to post my darned introduction!) and I just wanted to say... this is the single most helpful PDF I've ever seen!

[azr]

Wow, you're not kidding. Fantastic wiring diagram, wish we could get that for every bike.

[gottogochop]

Okay, Things are getting strange, So I put the battery on a trickle charger after I forgot to turn the key off, which drained the power. After checking my connections, I go to start it and it cranks over now. Its almost like it fixed itself, or I wiggled something tight? I've had the battery fully charged before, and it didn't crank, So I'm sort of mystified as to why it does now!

I checked spark, its good. But I noticed that it doesn't smell like gas after cranking it over. I'm thinking it should if gas is going un-burnt out the exhaust?

[BassCliff]

Greetings and Salutations!!

Hi Mr. gottogochop,

It sounds like your bike may have several issues, as most 30+ year old motorcycle tend to do. Here's some S.W.A.G. that I hope will help.

If you are here you probably have a 30 year old motorcycle that needs about 20 years worth of maintenance. You'll find all kinds of helpful tips, procedures, manuals, etc, in the links below. Let's get started.

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

[gottogochop]

Oh man! Thanks!

Here is the bike