• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Starting problem, no spark

  • Thread starter Thread starter geisterfahrer
  • Start date Start date
G

geisterfahrer

Guest
Not my GS750L, which is running fine, thanks in part to the wonderful people on this forum. It's my '83 Nighthawk 650. Similar vintage, and similar technology.

It started and ran great first thing this spring. Then it started getting hard to start with the starter motor. Then it got to a point where it could only be bump-started. Once started, it ran great. Now it won't start at all. No fire to the plugs. :cry:

I have checked the pickups, coils, and plug wires. All are within spec. The battery is new, and kept charged with a trickler. I have double-triple-quadruple checked the kill switch and clutch switch. I have replaced the ignitor unit (with a used one, of course, so no guarantees there).

I'm running out of ideas, and I hope someone here can help. What am I missing, that would cause the bike to gradually stop running? :-k

Sorry it's not a GS-specific query, but I've found the group here to be very knowledgable and far more active than the few Nighthawk-specific groups I've found.

Thanks!
 
Yes, the starter works fine. The engine turns over easily, and everything sounds just like it did when the bike ran. Just no fire.
 
do you have a wiring diagram and do you have voltage at the coils?

I work in romeo.
 
Last edited:
Dale,

I do have a wiring diagram in my Clymer manual. I'll check tomorrow about the voltage at the coils.

I work in Almont (most days, anyway :rolleyes:)

Kevin
 
Don't know those bikes... will normally crank and not fire when the side stand is up, or it won't crank at all with it up ?

Might have be a road trip involved :)
 
Last edited:
The '83 Nighthawk did not have the sidestand interlock. My '07 does :rolleyes:. I wish it were so simple!
 
'83 cb650sc? if that is correct, what I have read it has it. you would know better than what I found.
but as you say they work pretty much the same, shouldn't be to much of a problem to get it up and running.

possible to scan and post the diagram so I/we may peruse it?
 
Last edited:
Getting fuel? Only have to have three things for ignition: Fuel, air, and spark. Got all 3 there's no way it won't fire.
 
Definitely getting fuel and air. This spring, once the engine would start, the bike would run like a scalded dog. It just slowly became harder and harder to start.

I have tested for spark by plugging a known good spark plug into the boots, and grounding against the engine. No fire. I have confirmed the presence of fuel in the carbs, plus I can smell gas from the exhaust after cranking. I don't think it is a fuel issue. I suppose there could be an air problem, if the intakes were leaking, but wouldn't that cause the engine to run poorly once started?
 
If you had an intake leak the bike should start..would run like crap but would start.

Did you check to see if you have voltage at the coils? Check the primary and secondary resistance of the coils, as well as, resistance of the caps.
Check the wires going to your black box to make sure all connectors are clean and tight. Not sure exactly how you can test your ignitor but if you have a spare it might not be a bad idea to swap it out and see if you have spark.

Its been my experience that most electronic/computers in bikes and cars usually will fail spectacularly. Meaning they either work or they dont. They usually don't degrade over time. Corrosion which occurs over time could cause your electrical system to have problems. Did you check all your ground points to make sure all is tight and clean?
 
Smokinapankake said:
Getting fuel? Only have to have three things for ignition: Fuel, air, and spark. Got all 3 there's no way it won't fire.
Click to expand...
Just a little modification here.

Yes, there are three things needed, but the fuel and air become one item as a mixture.
The other two items are spark and compression.

.
 
almarconi;884671Did you check all your ground points to make sure all is tight and clean?[/quote said:
I'm inclined to agree with you on the failure mode of CDI ignitions. There has to be something that has progressed over time that has caused this problem. I have not had time to strip the bike down and check every ground point. I'm planning on doing that over the long holiday weekend, unless I decide I'd rather ride somewhere :p. I have a little time today, and I may start poking around.
Click to expand...
 
Check the voltage at the coils with just the key on and again when cranking.
if the voltage is above say 11.0 volts when cranking, then...
what is the resistance of the coils on the primary and secondary side and the resistance of the plug wires/caps if they are the type that can be removed.

I suspect that if originally it would start by cranking, then it began to have problems with intermittently starting when cranking bringing you to the point of having to bump start it. the voltage at the coils has begun to drop too low and it may have continued to deteriorate.

but it's only a guess at this point until further investigation.

***EDIT***
thanks for the diagram, voltage goes from the kill switch to the coils on the B/W? wires (hard to read the color codes on the diagram).
simple system, shouldn't be to hard to get it up and running.
 
Last edited:
Update: It's Alive!!!

Update: It's Alive!!!

I decided to spend some time with the 650 Nighthawk today. I rechecked the coils and pickups, all tested within spec. I replaced the spark plug wires because I had a new set sitting on the shelf (I don't think that was the problem, they wouldn't all fail at once). Then I started going through the wiring harness bit by bit, connector by connector. I used my DeOxit on every junction, and thoroughly cleaned the two chassis grounds, testing for fire after every step. Still nothing. Then I pulled the clutch diode out of its socket, tested it, cleaned it, and replaced it.

A cough! By golly, she coughed! I made sure the carb bowls were full, and cranked again with the choke on, and she fired :D.

I put her all back together, put a half gallon of gas in the tank, and took her for a short ride around the neighborhood. She was purring like a kitten. Unfortunately, she is not licensed, registered, or insured at the moment, so I couldn't take her out for a real ride :(.

Anyway, I'd like to say thanks to the GSR members who gave me advice and encouragement. I still don't really understand what the clutch diode does, or why cleaning its contacts could solve an ignition issue, but there it is :confused:.

Cheers,

Kevin
 
The clutch diode is not used in the GS bikes, so I will have to guess about its function until I can look at a wiring diagram.

There are probably a couple of items that share a ground, and the diode helps sense which one.

On '82-and-newer larger GS bikes, there is a light to show that your side stand is down. It is fed by the same wire that feeds the oil pressure light. There is a diode there to keep the signals straight so that a deployed side stand does not turn on the oil pressure light.

The clutch diode on the Nighthawk might share something similar. :-k

.
 
What did you find on you voltage check at the coils?? Your should have 12volts with a charged battery. If not then you might have to consider a relay between the battery and the coils. My 84 Suzuki exibited the same symptoms and my voltage at the coils was only around 10 volts due to built up resistance in the old wiring harness. I installed a relay and it cured my starting problem. Just a shot in the dark. Good luck and keep us posted.
 
You must log in or register to reply here.
Back
Top