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to spark or not to spark ?!

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Tricky.
the 900
the 900

Posts : 721
Location : Derby

to spark or not to spark ?!

Post by Tricky. on Mon 27 Jan 2014, 8:02 pm

started the bike up yesterday and it was missing one one cylinder, checked the spark on both sides and the left one was almost non existent. came back to it today, checked again and the right side had gone but the left came back. tinkered with other stuff for a while then checked again, now both sparks are almost non existent. 

ive tried changing the reg/rec, cdi box, and another set of coils, leads, plugs.

any ideas? 
where do the coils get their power?
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ANDYC
the 900
the 900

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Posts : 771
Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Mon 27 Jan 2014, 8:16 pm

If I remember correctly the 2 wires from the CDI to the coils provide the power pulse, it seems like they have got frayed or trapped somewhere. The earth wires to the coils would also give the same symptoms, so check that they have a good earth connection.
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si.p
Rossi
Rossi

Posts : 51
Location : Burgess Hill, West Sussex

Re: to spark or not to spark ?!

Post by si.p on Mon 27 Jan 2014, 8:39 pm

Sounds like a bad earth to me. Check the earth points to make sure that there is a good connection
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Tricky.
the 900
the 900

Posts : 721
Location : Derby

Re: to spark or not to spark ?!

Post by Tricky. on Wed 29 Jan 2014, 6:08 pm

apart from the earth wire that goes from the neg battery terminal to the engine casing, where else is there to check? does the coils bracket act as an earth?
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ANDYC
the 900
the 900

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Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Thu 30 Jan 2014, 8:30 pm

The blue/yellow and the yellow/blue wires are the trigger wires which determine when the spark should occur.
The black/white wire is common to both coils, and also to the starter button and the kill switch.
This does leave a lot of areas for a loose connection or a short, but at least you know which places to look.
The coil bracket doesn't have to be earthed.
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Tricky.
the 900
the 900

Posts : 721
Location : Derby

Re: to spark or not to spark ?!

Post by Tricky. on Thu 30 Jan 2014, 10:50 pm

ive changed the throttle side switch gear and its still the same.
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ANDYC
the 900
the 900

Mechanic
Posts : 771
Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Fri 31 Jan 2014, 7:44 am

Without a hands on approach I can't really help, but that's why I changed to the fireblade coil on plug set-up. Fewer connections that can cause problems.
Good luck with it.
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Tricky.
the 900
the 900

Posts : 721
Location : Derby

Re: to spark or not to spark ?!

Post by Tricky. on Sat 08 Feb 2014, 6:17 pm

still having a nightmare, low to no spark on one cylinder. 
has the generator/stator (left side crank case) got anything to do with power feeding the coils?
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ANDYC
the 900
the 900

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Posts : 771
Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Sun 09 Feb 2014, 6:52 pm

No, it shouldn't have.
The wires from the right hand engine case does though, these are the ignition pickup wires and tell the spark when to go. If these are damaged this will cause problems.
That is the right hand casing as you are sitting on the bike.
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ANDYC
the 900
the 900

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Posts : 771
Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Sun 09 Feb 2014, 6:56 pm

Just checking, what condition is your battery in?
Make sure that it is fully charged otherwise you will be chasing problems that are down to a poor battery.
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Tricky.
the 900
the 900

Posts : 721
Location : Derby

Re: to spark or not to spark ?!

Post by Tricky. on Sun 09 Feb 2014, 7:00 pm

ANDYC wrote:
The wires from the right hand engine case does though, these are the ignition pickup wires and tell the spark when to go. If these are damaged this will cause problems.
That is the right hand casing as you are sitting on the bike.

would i be able to check the output of these wires? 

what do the wires go to in the casing? will the item be replaceable?
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ANDYC
the 900
the 900

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Posts : 771
Location : Windsor

Re: to spark or not to spark ?!

Post by ANDYC on Sun 09 Feb 2014, 10:18 pm

The output is relatively low as they are more of a 'trigger' than a supply but yes it can be replaced.
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Navymike
Squiddy
Squiddy

Posts : 14

Re: to spark or not to spark ?!

Post by Navymike on Thu 18 Feb 2016, 10:41 am

Hi
I don't know whether this helps or not  I recently had a bit of a missing feel to my bike and traced it to one of the plug caps producing a very weak spark in contrast to the other. I found the brass insert in the plug cap which holds the resister in had somehow loosened causing an intermittent increase in resistance (worst measured at 200k) as the contents of the cap rattled around. a quick tighten with a flat blade screwdriver sorted this. also whilst I was there I replaced the original resistors and brass insert as thy were looking tired and reading 7k across the resister instead of 5k although the lead was still in spec so maybe not necessary but it will give me a few more amps at the plug. bike runs great again now.

Hope this helps

Mike

Guest
Guest

Re: to spark or not to spark ?!

Post by Guest on Thu 18 Feb 2016, 5:01 pm

"Thou shall measure voltages!"
In the fusebox a 10A fuse provides the current to the stop switch (OFF/RUN) from there current is branched to the starter switch, hence you can run the starter motor, the Ignition Control Unit (ICU), so it is powered, and the two ignition coils.  Measuring between ground and the two black/white cables on the ignition coils should give you the battery voltage when the stop switch is set to RUN. Test this and wiggle the wires where you can to see if voltage is there (at the coils) and stays there.
After that also measure resistance of the spark plug cap cables, they can be disconnected from the coils, hence a continuity test can be made.
And last but not least the ICU, the blue/yellow and yellow/blue provide a pulsed grounding of the ignition coils, it is this fast on/off switching that generates the the high voltage peaks, hence sparks, at the secondary of the coil. But as you have changed the ICU I don't think that the cause is there.
That being said, it's all theory. Good luck.

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