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Hi everyone, a newbie here, really hoping someone can help me out. I am an Electronics Engineer to trade, but this one is really start to make me question my capability. A few weeks ago my Foreman 450S suddenly refused to start. I have been through a great deal of investigation, which started by checking for a spark at the plug - but nothing when cranking. So, to cut a long story short, I have checked all the resistances in the stator windings, and in the Ignition Spark Generator coil, and all test out fine. Over the weeks I have been trying to fault-find, I have replaced the Ignition Coil, Battery, Ignition Spark Generator, but no change. My latest replacement was the Rectifier/Regulator, and there has been a change of symptom. I am now getting a spark when the start button pressed, but no sparks while the button is pressed in, and a second spare when the start button is released. I have seen a great deal of posts around no spark issues, but as I have completed a great deal of testing and replacement of crucial components, I now feel I need some guidance from the experts. So here I am, any help would be ever-so greatly appreciated. I really mean that.
 

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Hi everyone, a newbie here, really hoping someone can help me out. I am an Electronics Engineer to trade, but this one is really start to make me question my capability. A few weeks ago my Foreman 450S suddenly refused to start. I have been through a great deal of investigation, which started by checking for a spark at the plug - but nothing when cranking. So, to cut a long story short, I have checked all the resistances in the stator windings, and in the Ignition Spark Generator coil, and all test out fine. Over the weeks I have been trying to fault-find, I have replaced the Ignition Coil, Battery, Ignition Spark Generator, but no change. My latest replacement was the Rectifier/Regulator, and there has been a change of symptom. I am now getting a spark when the start button pressed, but no sparks while the button is pressed in, and a second spare when the start button is released. I have seen a great deal of posts around no spark issues, but as I have completed a great deal of testing and replacement of crucial components, I now feel I need some guidance from the experts. So here I am, any help would be ever-so greatly appreciated. I really mean that.
Your kill switch on the left side of handlebar isn't in off position is it?
 

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Discussion Starter #3
Thanks for the response. First thing I checked. When I switch it off, spark at start and end dissappear, switched on, sparks reappear, but only at button press, and button release, not in between.
 

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Are you using OEM parts or cheap china parts?
 

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Discussion Starter #5
All OEM parts. Did some more testing tonight, and I confirmed the pulses from the Stator (Ignition Pulse Generator) at 20Vpk (Positive Pulse, then a Negative Pulse, Pulse Width 10mS), which I think sounds about right. The pulse are a little ugly, but clean enough. The Yellow wire from one of the Stator lines is getting to the ICU, and measures approximately 10/11Vpk. The output of the ICU to the Ignition Coil is a mess. Result is a +130Vpk pulse when Start Button pressed in, then just noise around 0V while button is held in, then -130Vpk when button released. This explains why I am getting a spark at press, and then at release. So, I am fairly sure this points to the ICU. Anybody agree?
 
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