Honda CX 500 Forum banner
1 - 20 of 32 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter · #1 ·
I own bikes since 1964 and now I run into a problem I can't solve. Most annoying and humiliating.
My bike starts very easily, rev goes up to 7000 with no problem. I drive app. 1-2 km (or less) when one cylinder drops out followed by the other one in less than 10 seconds. Impossible to restart, no spark at all.
I checked terminal is the CDI interface, all resistances (cold and hot) are within the range, the hot values are slightly higher. The resistance of the advance pulse circuit is also OK - the one at the back of the engine, opposite the coolant tank.
I have two CD boxes, changing them makes no difference. I practically replaced every part in the ignition system except the ones inside the engine.
Charging current at idling is 0.2 A, and does not change with revving up. I have charging problems for a very long time, running on high beam the battery is drained in a half an hour. I suppose this has got nothing to do with the ignition. The engine runs well with battery terminals disconnected.
Coils have been replaced, they are OK. The initial spark is excellent.
I have a feeling that this problem is not related to the temperature of the engine, because it occurs before the engine significantly warms up.
I am not too keen on pulling the engine apart unless the defect is correctly diagnosed, although I have spare stator etc. to replace. Professional mechanics are useless (with very rare exceptions), they can only suggest to try this and that and see what happens.
I suspect that the signal to activate the CDI stops - but which signal and why?
Any idea would be greatly appreciated,.
Joseph Feredoes, Brisbane, Australia, [email protected]
 

·
Super Moderator
Joined
·
23,397 Posts
Try disconnecting the killswitch from the CDI unit. {black/white wire}.

On CDI bikes a dirty kill can flash over killing the bike which can be restarted after 5 minutes or so.

ASSuming your bike is CDI as you say it is an 82. Can you verify what you have?

If bike is CDI also check resistance between the three yellow battery charging wires and pin 9. There should be infinite resistance. No resistance here can cause some weird issues.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #3 ·
Try disconnecting the killswitch from the CDI unit. {black/white wire}.

On CDI bikes a dirty kill can flash over killing the bike which can be restarted after 5 minutes or so.

ASSuming your bike is CDI as you say it is an 82. Can you verify what you have?

If bike is CDI also check resistance between the three yellow battery charging wires and pin 9. There should be infinite resistance. No resistance here can cause some weird issues.
Try disconnecting the killswitch from the CDI unit. {black/white wire}.

On CDI bikes a dirty kill can flash over killing the bike which can be restarted after 5 minutes or so.

ASSuming your bike is CDI as you say it is an 82. Can you verify what you have?

If bike is CDI also check resistance between the three yellow battery charging wires and pin 9. There should be infinite resistance. No resistance here can cause some weird issues.
Hi,
Thanks for the fast response.
In the morning I severed the kill switch wire (BL/W), now the switch is disconnected. The bike did the same again, died after 1 km. This time I could restart it in 5 minutes. After another go, it died again as before but couldn't restart so far (app 5 hours later), I bet it will start in the morning on the first turn. So, the kill switch is off the list...
I checked resistances between the three yellow wires leading to the rectifier, all OK (zero resistance). Resistance between pin 9 and all three yellow wires is 385 Ohm (???). Definitely no short circuit, although you suggested open circuit (infinite resistance).
Unfortunately the defect remains unchanged... Thanks anyway, one problem is out...
 

·
Super Moderator
Joined
·
23,397 Posts
The stator may be the issue. But that's not conclusive. Doesn't sound promising though.

Try a quick ride with the fuel cap loose. You may have a blocked cap breather.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #5 ·
The stator may be the issue. But that's not conclusive. Doesn't sound promising though.

Try a quick ride with the fuel cap loose. You may have a blocked cap breather.
Thanks, my fuel cap has never been airtight. The problem is ignition. Looks like I have to replace the stator and pulse generators. Not too keen on it, although in the past I did it several times. This is why I want a definite diagnosis, not just replacing this and that... thanks anyway.
 

·
Super Moderator
Joined
·
23,397 Posts
You have pulse generators? The ignition system is transisterised if so. Is there any chance of a photo of some part of your ignition system to be sure we're on the same page?
 

·
Registered
Joined
·
1,697 Posts
have you checked the screen on the in-tank filter straw is clear?
 

·
Registered
Joined
·
1,697 Posts
and have you checked - when it has just stopped - that you have fuel in the carb bowls?
 

·
Super Moderator
Joined
·
5,333 Posts
Do you have an inline fuel filter fitted?
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #11 ·
You have pulse generators? The ignition system is transisterised if so. Is there any chance of a photo of some part of your ignition system to be sure we're on the same page?
I use CDI ignition, one original, one from Finland (fitted 8 years ago, goes well) / both OK. Pulse generators shown on attached pic. as well as all other components kept as spares.
At the moment - since it stopped yesterday - no ignition at all.
I am going through the system soon see what happened.
Thanks for the response,
Joseph
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #12 ·
I use CDI ignition, one original, one from Finland (fitted 8 years ago, goes well) / both OK. Pulse generators shown on attached pic. as well as all other components kept as spares.
At the moment - since it stopped yesterday - no ignition at all.
I am going through the system soon see what happened.
Thanks for the response,
Joseph
Idiophone Musical instrument Gas Font Electrical wiring

Do you have an inline fuel filter fitted?
Thanks for the response, I have plenty of fuel, no inline filter. The problem is positively electrical.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #14 ·
Try disconnecting the killswitch from the CDI unit. {black/white wire}.

On CDI bikes a dirty kill can flash over killing the bike which can be restarted after 5 minutes or so.

ASSuming your bike is CDI as you say it is an 82. Can you verify what you have?

If bike is CDI also check resistance between the three yellow battery charging wires and pin 9. There should be infinite resistance. No resistance here can cause some weird issues.
you may see all ignition parts on the pic.
Idiophone Musical instrument Gas Font Electrical wiring
 

·
Super Moderator
Joined
·
23,397 Posts
OK, you have a CDI bike fitted with a Finnbox G47 powered by a stock CDI stator. What you were calling pulse generators are the advance coils.

The original CDI box still works and has been swapped in as a control?

You have run through the whole stator test and all components register within spec per the test? But you have 385 ohms between the yellow charge wires and pin 9? What are your actual stator test figures?

It sounds like you need to do a voltage output test while cranking on the white wire.
 

·
Registered
Joined
·
16 Posts
Discussion Starter · #16 ·
OK, you have a CDI bike fitted with a Finnbox G47 powered by a stock CDI stator. What you were calling pulse generators are the advance coils.

The original CDI box still works and has been swapped in as a control?

You have run through the whole stator test and all components register within spec per the test? But you have 385 ohms between the yellow charge wires and pin 9? What are your actual stator test figures?

It sounds like you need to do a voltage output test while cranking on the white wire.
Thanks,
You mean voltage between white wire and any of the yellow ones?
 

·
Super Moderator
Joined
·
23,397 Posts
Positive probe to white {pin 8} negative to ground.

Run test on both AC and DC and give us your numbers. Test done while cranking engine over on the starter. Well charged battery is best.
 
1 - 20 of 32 Posts
Top