Random No Spark

[Nilson]

So my bike (1981 GS450L) has been randomly not starting from time to time.

Happened 3 times before:
1.) After riding (turned but wouldn't fire)
2.) It died during riding.(Would start, but then would quickly died again several time.)
3.) During a ride it died but after 2-3 mins cranking it started again and rode fine.

Because it happens periodically and inconsistently I have had trouble testing what is going on.
After it sits for 20-30 mins it always fires right up and runs fine.
I thought it was a fuel issue until today.

Today it wouldn't start from a cold start situation.
I ran through some trouble shooting and found I was getting no spark at either spark plug.
Let is sit for an hour and it fired right up. Fire at both plugs. It idled for 2-3 mins and died. No spark again.
Now it does this consistently runs for a minute or two dies no spark let is sit it starts back up.
I assume that there is a part that is getting hot and failing once it warms up. Any ideas what would do this that would cause both plugs to lose spark?

This is getting frustrating. Any ideas what the is going on here?

[eil]

Are you absolutely sure your battery is good and fully charged? A marginal battery can cause these exact symptoms. If this is the case, your battery might be marginal because the charging system isn't working. (Search the forum for posplayr's threads, he has a link in his signature for procedures to check your charging system.)

Failing that, have you meticulously cleaned all of your electrical connections?

If all of the above pass muster, you might have a bad ignitor. But this is somewhat less likely than the issues above. Even less likely still (but minutely possible) is two bad coils.

[Nilson]

I will check that.
If it were the battery or charging system wouldn't it have trouble cranking?
It cranks fine has lights etc. it just gets no spark.

[tom203]

Even though it cranks (but no spark), it could be a bad connection at kill switch (or after ) that doesn't feed the ignition coil circuit at times.best to remove tank add a jumper wire to orange/white wire feeding both coils .secure this carefully ,reinstall tank, and hang other wire end someplace (with end insulated) where you can test it next time this stuff happens. This jumper should show 12 volt positive with key and kill switch "on" at all times .

[Nilson]

Ok it seems bad connections to the ignitor or bad ignitor are the two most likely options?
If I were to check connections which ones need to be looked at and in which order?
Is this a visual check or do I need to multi meter each one to make sure 12v is present?
Is there a way to test the ignitor it self?

Sorry if these are stupid questions. I am new to bike repair so this seems daunting to me...

[JTGS850GL]

Start with a set of circuit schematics and a multi-meter. Visual inspection wont get you much unless you can see electrons.

[tom203]

Sure, check all the connections,but a random problem like yours can be challenging to find unless you hit it at right time- i.e. ,when it won't fire. Go here do some reading....

http://members.dslextreme.com/users/storagecliff/images/electrical_odd-n-ends.html#A17

I take it that this is a new-to-you bike. Do you know much about its maintenance history?

[Nilson]

Yes this is a fairly new to me bike.
I have put in a bit over 1000 miles sense getting it in October.
I had to replace the starter, grounding and frame screws were missing in the starter relay and R/R so it had a bad ground to the the frame I replaced those. This issue started a few weeks ago. It was after changing the handle bars I believe, but not 100% sure.
It is possible that the issue existed before, but I have know way of knowing.

[tom203]

"......This issue started a few weeks ago. It was after changing the handle bars I believe, but not 100% sure."

a clue! You fiddled with the right switch,so maybe you disturbed kill switch wiring causing an intermittent break in circuit to coils at times.
1000 miles of riding is bound to turn up issues. Are you a kill switch user, or do you turn key off to power down?

[wymple]

You are at the least losing the hot lead to the coils. I bet you can run a hot wire from the battery to the coils and it will run fine. And that will tell you to simply clean up the wiring involved, (I run it new) and you'll be fine. Only other thing would be the ground, and I doubt that.

[Nilson]

So it is looking like it is my CDI ignition box.
New looks like the cheapest is $500, which is what I paid for the whole bike.
Is this a part that I could go used on and have luck? Do the things go bad on a normal basis after 30 years?

[tom203]

So it is looking like it is my CDI ignition box.
New looks like the cheapest is $500, which is what I paid for the whole bike.
Is this a part that I could go used on and have luck? Do the things go bad on a normal basis after 30 years?

No, but a charging problem could give an ignitor fits- electronic stuff doesn't like excessive voltages.

I'd do the jumper wire test as here ,before I pronounce the ignitor guilty..... Remember this?try it..

"Even though it cranks (but no spark), it could be a bad connection at kill switch (or after ) that doesn't feed the ignition coil circuit at times.best to remove tank add a jumper wire to orange/white wire feeding both coils .secure this carefully ,reinstall tank, and hang other wire end someplace (with end insulated) where you can test it next time this stuff happens. This jumper should show 12 volt positive with key and kill switch "on" at all times ."
This random stuff is very annoying
i think member Pete from down under put a dyna ignition on his 450

[Brendan W]

How have you diagnosed the cdi box?
I had a similar issue that turned out to be the plugs at the box. With the bike running I could wiggle them and get it to cut out. Likewise after a stop on a ride out I could wiggle them and get it to start.
Electronics normally fail hot but you are having cold problems.

[eil]

So it is looking like it is my CDI ignition box.
New looks like the cheapest is $500, which is what I paid for the whole bike.
Is this a part that I could go used on and have luck? Do the things go bad on a normal basis after 30 years?

No, you're guessing that it's your CDI box* because you haven't done any troubleshooting yet. All you have is a set of symptoms which could be caused by any number (or combination) of things. You can just start swapping parts if you want but that's a pretty expensive and time consuming way to go about it. A better way is to employ Science and locate the fault through the process of elimination. Clean and reseat all electrical connections including grounds, check your charging system health: http://www.thegsresources.com/_forum...31#post1138531 check to make sure you have enough voltage going to the coils, test the coils according to the service manual, and so on.

Maybe the ignitor is bad, they do seem a little more prone to failure on the 450s and 550s compared to the bigger bikes for some reason, but replacing it is expensive. It would make more sense to rule out the less expensive (even free) fixes first.

(* Also, your bike doesn't have a "CDI box", it has an transistorized ignition box, or what most of us just call the "ignitor".)

[Nilson]

No, you're guessing that it's your CDI box* because you haven't done any troubleshooting yet.

Guilty as charged. I am guessing at this point.

All I have done at this point is a visual check of of connections and reseating all connections that can be disconnected and reconnected. I understand that is not really checking much. I think this particular issue may be a bit over my head at this point. I getting more comfortable at strait forward mechanical repairs, but the electrical system seems tricky.

Luckily, I have found a retired bike cop in my area that now works on bikes out of his garage. He has agreed to help trouble shoot the problem. I will report back the issues that are found.

Thanks for the info and dose of reality.