1983 Honda CB650 Nighthawk Ignition Problem

[vwarnick]

Worked on it all winter and got it running. All of the sudden it won't start. Trying to work my way though the issues, but figured I'd ask for some help here. Using the Clymer manual as a reference, here is what I've done so far:
1. I've brought a Spark Unit and replaced the old one. That didn't solve the problem
2. Per instructions on page 189 I've tested the pickup coils as documented in step number 3 under CDI trouble shooting. The resistance reading I get is correct
3. I've done the Dynamic Test for ignition coils as documented on page 190 of the manual. Essentially, remove the spark plug, plug it back into the wire, hold the base against the cylinder head for a ground, and crank the engine. I got no spark. Did this test for both coils.

My guess is that I have to get a new set of coils. Anyone have a different opinion? Anyone care to comment on why both coils went at the same time? Thanks in advance.

[GS_in_CO]

My guess is that I have to get a new set of coils. Anyone have a different opinion? Anyone care to comment on why both coils went at the same time? Thanks in advance.

Too much of a coincidence. Both coils "bad" at the same time is highly unlikely.
You're overlooking something. (kill switch wiring? Sidestand switch wiring?)
Check resistance of the primary and secondary windings of the coils.
Then check for primary voltage reaching the coils when cranking.

Those are the generic steps. I don't know how you do those things on your particular machine.

[GS_in_CO]

To expand a little further-

About 6 weeks ago my bike suddenly lost power and backfired.
The backfire told me that it was getting fuel (which it dumped into the exhaust system and detonated). I coasted to the side of the road and turned the ignition off. Thought about it awhile.
Decided that I'd had an ignition failure and that the easiest thing to do while sitting on the bike at the side of the road was to exercise the kill switch.

I cycled the switch about 5 times then restarted the bike and rode it home (15 miles)without a hiccup.

I then went thru it connector by connector cleaning the contacts with Deoxit contact cleaner.

Several hundred miles later the problem hasn't returned. I don't know which action fixed it for sure.

But loss of ignition is usually a very simple problem to find - if you know how things work.

[Hanson]

Hi Skip, welcome to the forum.

I hope you will let us know how you get this issue sorted out and I would love to see some pictures of your classic Honda.

Safe Travels,
Richard

[vwarnick]

Did some reading and testing.

I have spark on all four cylinders. My earlier test was done during the day and I missed the spark.

Replaced the petcock valve last winter, but tested it again and all seems to be well there.

Today with the gas tank off, I removed the air filter and squirted some starter fluid into the intakes and cranked the bike. Got a bunch of gurgling and it seems as though I am getting gas or some other fluid back into the air filter compartment. Have repeated the cranking, sans starter fluid, multiple times and still get the gurgling. Where would the gas be coming from except from the carburetors? And, with the gas tank off, shouldn't the gurgling stop? I'm really stumped now.

[BRUMBEAR]

If you have spark and Compression carbs are shyted up valves are not hangin so pull em rebuild em all will be well

[jbethune]

I have a 1984 that I brought back from a rough couple seasons sitting unused. I find you can get some clues to why it wont start from the different sounds..Does it start at all and die, or just nothing? How old is your gas? New gas can do wonders...
The clymer should have a good description of different spark plug foulings. If you look at your plugs and compare with the clymer (and online images) you might have some luck diagnosing. Finally, before you do much with the electrical system, I would take apart the carbs. Much easier to fix if its just a cleaning task.
Let us know..

[bdavis205]

Hi Skip

did you find out what the GURGLING noise was ???

did you replace the jets in the carbs ?

I have the same GUGLING noise on my 1984 CB650 nighthawk when cranking it and it will not start the noise comes from the air box area

[mwierda]

Hi there - I know this post is now nearly 10 years old, but as a long shot - my 83 cb650 is exhibiting the exact same behavior described by a few folks here. (Gurgling sound, a fluid that seems like water pushing back into the air box).

Were you ever able to figure out the issue?

[Mirza99]

Although the 1983 Honda CB650 Nighthawk is a legendary motorbike renowned for its dependability, ageing parts might cause ignition problems. Regular maintenance and occasional upgrades to ignition systems can help ensure continued performance and reliability on this iconic model.