Won't start, no spark

[77_GS750]

New GS owner here.

My '77 GS750 won't spark. I rode it around fine for the first time this season on the weekend. It just came from the shop for a tune up since storage.

It stalled out right when I was parking it at home. I'm still new to riding it so I thought it was my fault.

I tried starting it up the next day and it wouldn't go. Pulled the plugs, they were black so I decided to start fresh with some new ones. Still nothing. Pulled them out to see if there was a spark and wasn't seeing any on any of the plugs.

This is my first bike so I feel I've done what my limited knowledge is capable of at the moment. Any suggestions why I'm not getting a spark?

[BassCliff]

Greetings and Salutations!!

Hi Mr. 77_GS750,

There are troubleshooting tips in the electrical section of my little website.

Let's start with: What is the battery voltage at rest? What is the voltage when you try to start the bike? Does the engine turn over slowly/quickly? What other maintenance have you performed? See the maintenance lists in your "mega-welcome". On a 30+ year old bike, all of the tasks are pretty much mandatory, especially if you are unfamiliar with the bike's maintenance history.

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

[spyug]

Welcome. Cliff has given you all the info you are going to need to sort things out but now its up to you to read and impliment.

As he says, the first thing is to insure you have a fully charged battery and to verify this, you will need a digital multimeter (available just about everywhere for $10 and up). You will set it to the DC voltage setting of at least 20 volts. With the key off check the battery and you will need at least 12.5+ volts. If less than that its going to be hard to start as voltage is shared by the coils and the starter motor and with the old wiring the full voltage is not going to get where its needed. You should clean up all the wiring and connectors but that's a job for a bit later.

If the voltage is lower than mentioned then you will need to charge it or boost it. If charging you want to use a charger capable of charging at 2 amps or less ( usually motorcycle specific). If boosting from a car battery make sure the car engine is off or you may cook your bike's electrics.

Check your fuse block to see all fuses are good.

Once you have a charged battery see if you are producing spark. Use a spare plug and rest it on the engine to check for spark. Try it on each plug lead as one or more are likely to show some spark. If a couple are not, you can suspect the plug caps that screw in to the leads. They become very resistant over time and the spark doesn't get through. Change them (about $7 each) and that should fix it.

If still no spark you may have a problem with the wiring or connectors. Connectors get corroded over time and corrosion is resistance to electrical flow so they need to be cleaned. But lets not get too far ahead. Test the battery and lets see what you have.

Good luck and let us know what you find.

Cheers,
spyug

My apologies if I seem to talk down to you but I don't know the depth of your mechanical knowledge but am guessing from what you wrote that its quite limited.

[77_GS750]

Thanks guys, I'll test the battery tonight and post back if it doesn't (or hopefully does!) remedy the problem.

I have a feeling I'll be asking a lot more tips/questions when I'm back to riding!

[MisterCinders]

You only have one fuse.

When the plugs were black, were sooty dry black or oily wet black?

Also put your location in your profile.