TOPIC:

Following on from my issues with the carbs I now have a weak spark.
Having gone through all the suggestions with the carb cleaning I put the carbs on and it started after only after using two battery's. The good news is it looks like the carbs will be ok now.
Having got the bike started I put every thing back on the bike and tried to start it again but it was having none of it.
I took all the plugs out and checked the spark and found it to be weak with 3/4 dropping out altogether.
This is fitted with a Dyna 2000 electronic ignition and the 3ohm coils.
I took the pick up mounting plate out and removed the ht leads off 3/4, I then checked all the various wires and they all had good continuity. I then checked the pick ups by moving a magnet over them and they all produced a spark. The coil (3/4) with the ht leads removed produced a spark from the coil down to the frame and the spark was excellent, when I turned the bike over with the starter motor the spark on 3/4 disappeared and the spark on the other coils (ht leads still fitted with plugs) produced a very weak spark. This all points to the starter motor dragging the battery down ( I have 32 amp battery fitted at the moment)
I have stripped the starter motor down, checked the brushes and cleaned the armature so it does seem to be ok. I do not have a mega but I do have a multi meter and a ammeter. I have also disconnected all lights and removed all the fuses except the main 30amp fuse.
I have also put another temporary earth in just to make sure its not a bad earth.
Could this be any thing other than the starter motor?

Hi SixPipes,

What voltage to you have at the primary side of the coils? Should be very close to the voltage at the positive side of the battery.

Bill

Put your volt meter across the battery terminals and crank over the motor. You should be able to maintain a minimum of 8 volts during cranking. If it drops below 8 volts you either have a problem with the starting circuit or a weak battery. The two large terminals in the starter solenoid can pit and when they get excessive pitting the resistance across the terminals goes up and that will draw more amps which drops the available voltage left for the ignition circuit.

Also when you put in the Dyna's did you remove the ballast resistor from the ignition circuit and bypass the wiring? 3 ohm coils plus the 1.2 ohm ballast will drop the output of the secondary voltage at the coil. Marry that up with a weak primary voltage and you get very little spark.

Hope this helps.

I have 12.74v at the battery, I have removed two wires from the coil and connected the meter across them and turned the bike over, ouch - I only have 4 volts at the coil.
It looks as if the ballast resistor has been removed. I have also found 4 wires that have been disconnected.
Yellow female connector - blue,green and black - male - these have been taped up seperatly.
Just going to look through the wiring diagram to see what they are and try and find the ballast cables.

4 volts at the coil - good to know. Back to what I suggested. Put your voltmeter across the battery and take a reading while cranking over the starter. That will tell you how much voltage you have in reserve during cranking. If it's less than 8 volts, you need to find out where the excessive draw is or why the battery is too weak to handle the full load at cranking. I suspect a bad connection on your starting circuit or a pooched battery.
If you find 8 volts at the battery while cranking and only 4 volts at the coil, you'll have to find the corrosion in the feed to the coils.

11.00 v at the battery when its turned over - so I guess I am now looking for a very bad connection. Relay to starter motor, what about the starter motor could that do it?
The wires I found disconnected I think are the old coil wires.
Just looking for this ballast resistor now just to make sure - what does it look like?
I can get 11.5v at the coil depending on where the magnet stops in relation to the pick ups, however when the motor is turned over that drops to between 1 - 4 volts, I think if I put the plugs back in the voltage would drop off the scale.
Starter relay was in very good condition but that is all cleaned now. Spark is still the same - weak.
Just a thought, it cant be the starter motor because if i remove the pick up plate and move a magnet over the pick nups the spark is still weak