Posted by I am Tosk on January 4, 2011, 6:15 pm
OK, my 04 KX 125 won't start so I checked the spark, no spark... Well, I
saw one spark, but it was lonely.. So they want $70 to diagnose weather
it's the coil, magneto, crank angle sensor, or CDI Box... one hour
labor. But I used to do just this on cars in another life, I just have
some questions.
I am not sure if there is power from the CDI to the Magneto and Crank
Angle Sensor, or if they just produce a pulse alone, which seems to make
more sense as there is no battery in the circuit?
My second question is can I check the Magneto and Crank Angle Sensor
with a test light, in my past life I would have used an oscilloscope but
I don't have one handy?
OK, assuming they create their own pulse, here is my test flow. The
following assumes all mechanical and wiring has been checked for
connection and operation/broken pieces etc...:
Check for spark at plug, if no spark at plug, check for pulse on low
side of coil circuit from CDI to the Coil. If you have a pulse through
the low side and there is still no spark, replace the coil.
If you have no pulse from the CDI Box to the Coil, Check the Crank Angle
Sensor for a pulse to the CDI Box, if it's bad, replace/repair Crank
Angle Sensor.
If you still have no pulse from CDI to the coil, check the Magneto
circuit, for a pulse to the CDI Box, if it's bad, replace or repair the
Magneto.
If the Crank Angle Sensor is good, and the Magneto circuit is good, and
there is still no pulse to the Low side of the Coil, replace the CDI
Box...
Does this sound about right?? Thanks in advance, I have to get this
thing figured out soon, the bike is for sale;)
--
Rowdy Mouse Racing - Pain is temporary, Glory is forever!
Posted by KW on January 4, 2011, 7:06 pm
> OK, my 04 KX 125 won't start so I checked the spark, no spark... Well, I
> saw one spark, but it was lonely.. So they want $70 to diagnose weather
> it's the coil, magneto, crank angle sensor, or CDI Box... one hour
> labor. But I used to do just this on cars in another life, I just have
> some questions.
> I am not sure if there is power from the CDI to the Magneto and Crank
> Angle Sensor, or if they just produce a pulse alone, which seems to make
> more sense as there is no battery in the circuit?
> My second question is can I check the Magneto and Crank Angle Sensor
> with a test light, in my past life I would have used an oscilloscope but
> I don't have one handy?
> OK, assuming they create their own pulse, here is my test flow. The
> following assumes all mechanical and wiring has been checked for
> connection and operation/broken pieces etc...:
> Check for spark at plug, if no spark at plug, check for pulse on low
> side of coil circuit from CDI to the Coil. If you have a pulse through
> the low side and there is still no spark, replace the coil.
> If you have no pulse from the CDI Box to the Coil, Check the Crank Angle
> Sensor for a pulse to the CDI Box, if it's bad, replace/repair Crank
> Angle Sensor.
> If you still have no pulse from CDI to the coil, check the Magneto
> circuit, for a pulse to the CDI Box, if it's bad, replace or repair the
> Magneto.
> If the Crank Angle Sensor is good, and the Magneto circuit is good, and
> there is still no pulse to the Low side of the Coil, replace the CDI
> Box...
> Does this sound about right?? Thanks in advance, I have to get this
> thing figured out soon, the bike is for sale;)
> --
> Rowdy Mouse Racing - Pain is temporary, Glory is forever!
I can't help you with the circuitry diagnosis.....but I would suggest a
fresh... known good plug....(as in verify spark by testing in the plug boot
of another bike) before going any further in the testing.
Sometimes its the simplest things.
KW
Posted by sturd on January 4, 2011, 7:28 pm
I am Tosk asks,
> > OK, my 04 KX 125 won't start so I checked the spark, no spark... Well, I
> > saw one spark, but it was lonely..
I agree with Keith, the only thing you left out of your test sequence
was the replacement of the spark plug with a new one first.
New.
Go fast. Take chances.
Mike S.
Posted by I am Tosk on January 9, 2011, 10:29 am
In article <8c27385f-f021-4ccc-840f-
c376e6a2fbcb@l32g2000yqc.googlegroups.com>, mikesturdevant127
@hotmail.com says...
>
> I am Tosk asks,
>
>
> > > OK, my 04 KX 125 won't start so I checked the spark, no spark... Well, I
> > > saw one spark, but it was lonely..
>
> I agree with Keith, the only thing you left out of your test sequence
> was the replacement of the spark plug with a new one first.
>
> New.
>
>
> Go fast. Take chances.
> Mike S.
Just for the record, that was the first thing we did at the track.. As a
matter of fact, we tried two, both fresh from the box...
--
Rowdy Mouse Racing - Pain is temporary, Glory is forever!
Posted by I am Tosk on January 4, 2011, 8:14 pm
keith_warrennospam@windstream.net says...
>
> >
> > OK, my 04 KX 125 won't start so I checked the spark, no spark... Well, I
> > saw one spark, but it was lonely.. So they want $70 to diagnose weather
> > it's the coil, magneto, crank angle sensor, or CDI Box... one hour
> > labor. But I used to do just this on cars in another life, I just have
> > some questions.
> >
> > I am not sure if there is power from the CDI to the Magneto and Crank
> > Angle Sensor, or if they just produce a pulse alone, which seems to make
> > more sense as there is no battery in the circuit?
> >
> > My second question is can I check the Magneto and Crank Angle Sensor
> > with a test light, in my past life I would have used an oscilloscope but
> > I don't have one handy?
> >
> > OK, assuming they create their own pulse, here is my test flow. The
> > following assumes all mechanical and wiring has been checked for
> > connection and operation/broken pieces etc...:
> >
> > Check for spark at plug, if no spark at plug, check for pulse on low
> > side of coil circuit from CDI to the Coil. If you have a pulse through
> > the low side and there is still no spark, replace the coil.
> >
> > If you have no pulse from the CDI Box to the Coil, Check the Crank Angle
> > Sensor for a pulse to the CDI Box, if it's bad, replace/repair Crank
> > Angle Sensor.
> >
> > If you still have no pulse from CDI to the coil, check the Magneto
> > circuit, for a pulse to the CDI Box, if it's bad, replace or repair the
> > Magneto.
> >
> > If the Crank Angle Sensor is good, and the Magneto circuit is good, and
> > there is still no pulse to the Low side of the Coil, replace the CDI
> > Box...
> >
> > Does this sound about right?? Thanks in advance, I have to get this
> > thing figured out soon, the bike is for sale;)
> >
> > --
> > Rowdy Mouse Racing - Pain is temporary, Glory is forever!
>
> I can't help you with the circuitry diagnosis.....but I would suggest a
> fresh... known good plug....(as in verify spark by testing in the plug boot
> of another bike) before going any further in the testing.
>
> Sometimes its the simplest things.
>
> KW
Guess I should have mentioned I tried two new in the box plugs and also
the old, screwdriver to the side of the header... Humm, just thought of
something, is there a possibility my "Bills" header is non-conductive?
Anyway, I should also note it's getting fuel and has compression..
Thanks.
--
Rowdy Mouse Racing - Pain is temporary, Glory is forever!
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> saw one spark, but it was lonely.. So they want $70 to diagnose weather
> it's the coil, magneto, crank angle sensor, or CDI Box... one hour
> labor. But I used to do just this on cars in another life, I just have
> some questions.
> I am not sure if there is power from the CDI to the Magneto and Crank
> Angle Sensor, or if they just produce a pulse alone, which seems to make
> more sense as there is no battery in the circuit?
> My second question is can I check the Magneto and Crank Angle Sensor
> with a test light, in my past life I would have used an oscilloscope but
> I don't have one handy?
> OK, assuming they create their own pulse, here is my test flow. The
> following assumes all mechanical and wiring has been checked for
> connection and operation/broken pieces etc...:
> Check for spark at plug, if no spark at plug, check for pulse on low
> side of coil circuit from CDI to the Coil. If you have a pulse through
> the low side and there is still no spark, replace the coil.
> If you have no pulse from the CDI Box to the Coil, Check the Crank Angle
> Sensor for a pulse to the CDI Box, if it's bad, replace/repair Crank
> Angle Sensor.
> If you still have no pulse from CDI to the coil, check the Magneto
> circuit, for a pulse to the CDI Box, if it's bad, replace or repair the
> Magneto.
> If the Crank Angle Sensor is good, and the Magneto circuit is good, and
> there is still no pulse to the Low side of the Coil, replace the CDI
> Box...
> Does this sound about right?? Thanks in advance, I have to get this
> thing figured out soon, the bike is for sale;)
> --
> Rowdy Mouse Racing - Pain is temporary, Glory is forever!