Help wanted for Honda CX500 ignition problem / CDI info wanted.

[EastLion]

Kees Wielinga wrote:
>
> Can someone please help me find the cause of my ignition problem?
> I have a 1978 Honda CX 500, which runs badly.
> Although the carburetters need adjustment, the main cause is almost
> certainly in the ignition. According to one mechanic, a faulty CDI unit is
> likely. A building scheme of such a unit would be greatly appreciated.
> All other suggestions are welcome too.
>
> Symptoms:
> A loss of power, abnormal reaction to opening the throttle, originally
> mostly in the range from some 3000 to 6000 rpm.
> At 6000 and higher it was almost normal. Now the higher rpm's cannot be
> reached any more, at least not when under load.
>
> Checking the ignition advance with a stroboscope showed a superficially
> normal looking advance (visibility is poor, under a shower of engine oil).
> When running irregularly, there were at the same time irregularities in the
> flashing of the stroboscope, like missing flashes.
>
> The opening position of the throttle also has an influence. For example, at
> 4000 rpm it runs almost normally, but if I open the throttle then, the
> reaction is one of protest, consisting of stuttering, some backfiring, and
> staying below 5000 rpm. Only slow opening of the throttle can bring the
> engine to the higher rpm's, and only when running idle.
>
> This is the situation today. In its better days, the problem is less
> severe. The higher rpm's can then be reached also when riding, allbeit
> sometimes after temporarily changing gear from 5 to 4, and upward again
> after sufficient speed is made to keep it above 5000 rpm in the 5th gear.
>
> I suspected the advanced ignition, and still do till now, but there is one
> thing contradicting that possibility: When I detach the connector that is
> according to Haynes only for the advancer pulse, the engine will not start
> at all. When detached during running, it stops immediately.
> In my theory this makes no sense, because the fixed pulser would still
> trigger a spark. Could it be that my advanced pulsers are the only pulsers
> that work at all? In that case, I don't understand why there are fixed
> pulsers in the first place.
>
> I hope you can make something out of the symptoms...?
>
> Kind regards, Kees Wielinga

Check the pulse coil connections, and all the ignition system
connections. Start at the CDI unit, or look at a schematic (available
at most public libraries), and inspect all the connections. Also check
the advancer to see that it's free to advance the pulsewheel. Good
luck.
EastLion

[Rick Spurlin]

Over the years, I've had similar problems with other bikes and cars.
Almost always it's a little tiny piece of dirt that blocks a jet. The
reason it doesn't show up when you're at cruse is because it falls away from
the jet a little bit. However, once you open the throttle, all of that
gasoline and the little piece of dirt try to shoot through the jet. Try
cleaning out the carb and blowing out any little pieces of dirt you may
find. It won't be big, just a tiny little piece is enough to ruin your
whole day.

Rick

[John Lamp - remove .nospam to mail]

"Rick Spurlin" <no-spam....@no-spam.c-pages.com> writes:

Rick has jogged my memory! My CX behaved as described a while back after a
service. A major throttle wide open fang around the traps cleared the problem.
I'd definitely check the jets.

Cheers
John

_--_|\ John Lamp, originating in Hobart, Tasmania
/ \ email: jw_...@calvados.apana.org.au
\_.--._/ APANA? email in...@apana.org.au
v <----<< CX500 Ulysses #10185 DoD #1906

[bob young]

wiel...@worldonline.nl (Kees Wielinga) wrote:

>Kind regards, Kees Wielinga

Had a similar problem with my cx500, Mine came good after cleaning
the filter in the fuel tank and stripping the carbies and cleaning out
the bowls.
To get at the filter, empty the tank and remove the petcock,on top
there is a central nylon tube and a nylon filter surrounding it, on
mine this was clogged with scale.
I removed the carbies and in one of them there was foreign matter
which must have blocked the jets every now and then.
That was 18 months ago and it hasn't missed a beat since.

good luck,

Bigbob....

[Eric Graudins]

>wiel...@worldonline.nl (Kees Wielinga) wrote:
>
>
>>Can someone please help me find the cause of my ignition problem?
>>I have a 1978 Honda CX 500, which runs badly.
>>Although the carburetters need adjustment, the main cause is almost
>>certainly in the ignition.

<Lots of description snipped>

Have you checked the connection on the HT leads where they enter
the spark plug connector?
To check this, twist off the connectors, and look at the end of the
HT lead. One of mine was full of green gungy stuff, with nary an
intact copper wire in sight.
If necessary, cut of 15mm or so of HT lead, and screw the connector
back on. (Careful that you don't cut off too much - there's not a lot
to spare)

After I did this, the mysterious miss under power disappeared totally.
I too was told that the CDI was stuffed, and would have to be
replaced. (I've since done another 40,000 km - no problems!)

Regards,
Eric G.

____________________________________________________________________

AND on the 8th day, the lord said "OK Murphy, you can take over now"
____________________________________________________________________

[Jamie Webb]

Once upoun a time on Mon, 15 Sep 1997 12:09:20 GMT,a person,
be...@ozemail.com.au (Eric Graudins), spake on the aforementioned
subject thusly:

>>wiel...@worldonline.nl (Kees Wielinga) wrote:
>>
>>
>>>Can someone please help me find the cause of my ignition problem?
>>>I have a 1978 Honda CX 500, which runs badly.
>>>Although the carburetters need adjustment, the main cause is almost
>>>certainly in the ignition.
><Lots of description snipped>
>
>Have you checked the connection on the HT leads where they enter
>the spark plug connector?
>To check this, twist off the connectors, and look at the end of the
>HT lead. One of mine was full of green gungy stuff, with nary an
>intact copper wire in sight.
>If necessary, cut of 15mm or so of HT lead, and screw the connector
>back on. (Careful that you don't cut off too much - there's not a lot
>to spare)
>
>After I did this, the mysterious miss under power disappeared totally.
>I too was told that the CDI was stuffed, and would have to be
>replaced. (I've since done another 40,000 km - no problems!)
>

With out seeing the Original post (it didn't come throught here), I
would suggest that you check your timing. A freind's CX's alternator
played up, with the result that it lost spark under load.
--

I choose to put my Sig block here!

Jamie,DOTFM#5 Have a day! :-|

http://www.users.bigpond.com/jawebb
jaw...@Bigpond.com