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Author Topic: Honda starting Issues Help please!  (Read 311 times)

Offline TwinEagle___

  • Posts: 5
Honda starting Issues Help please!
« on: Apr 20, 2019, 07:26:26 »
Hello every one!

Last summer i bought myself a  1979 honda cb400n. it was running okay. In the summer i did some maintenance (oil, filters, spark plugs,...) trying to keep it original (and trying to make a little profit). But i started to like the bike myself so i got my licence last month. In the winter I started it a couple of times and it went okay. Now it's been 3 weeks since it last ran and i can't get it to start. I renewed the gas and I know it gets to the carbs. I also checked the spark which is fine. Since there are new spark plugs, the length of the spark has to be correct.
Electric start or kick start makes no difference. Battery is okay, fully charged it.
It turns over but doesn't start. I also bought starter fluid to help it but it makes no difference (tried spraying in the air filter and after in the spark plug holes straight into the cilinder).
I'm running out of ideas here and getting kind of desperate.
I read online the CDI unit on these bikes likes to break but then I would not have any spark I believe.

So if anyone has some tips or experiences in this situation, I would be glad to hear them :D :D

Kind regards,
Wouter Smet

Offline trek97

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Re: Honda starting Issues Help please!
« Reply #1 on: Apr 20, 2019, 09:44:55 »
Fuel is on
kill sw is on
choke pulled
key on
in neutral

Check to be sure the choke cable didn't slip through the clamp on the carbs. (ensure the choke plates are getting fully closed)
If its flooded pull the plugs and crank it with no choke and wide open throttle for a bit.  Then install plugs and try it again.
may be clogged pilots jets, on Rachels CB400A they are kinda sorta easy to pull without removing carbs.  (If they are clogged, pull disassemble and clean carbs...ensure all passages are clean). Rachels pilot circuits were so badly clogged I wasn't able to clean them.  Sent them out to https://murrayscarbs.com/ He did an awesome job with them.

Avoid using ethanol fuel. 

Because you've already tried it with starting fluid...

You can check timing with a stroboscopic timing light while cranking it.  Easiest with a helper to hold start button.

If you still have good spark and battery is fully charged, check carb boots for cracks or other vacuum leaks.

iPhone and strobe light dont play well together.

« Last Edit: Apr 20, 2019, 10:25:05 by trek97 »

Offline TwinEagle___

  • Posts: 5
Re: Honda starting Issues Help please!
« Reply #2 on: Apr 21, 2019, 06:13:56 »
Thank you very much for the help. Tomorrow I'm trying it out. I did forgot to mention that i have a loud bang from the exhaust sometimes while cranking, so I am guessing the fuel is getting to the cilinders and to the exhaust. But still I'll check the carbs and the choke cable and the timing (first finding a stroboscope somewhere).

Kind regards,
Wouter Smet

Offline TwinEagle___

  • Posts: 5
Re: Honda starting Issues Help please!
« Reply #3 on: Apr 28, 2019, 06:59:37 »
Hey every one,

I managed to get it running again.
There were two sides to the problem: the spark plugs were both broken (the sparks doesn't go between the elektrodes but fram the center to the outside). And the jets in the carb were pretty clogged up. So I cleaned them en also the float bowls. It runs now with bad spark but new spark plugs are on the way.

Now finishing the project: painting the fuel tank, installing a loop around the seat and securing the new speedo. Then it's pretty much finished :)

Kind regards,
Wouter Smet