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| voltage needed http://www.kawi2strokes.com/forum/viewtopic.php?f=14&t=14973 |
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| Author: | 0120raptor [ Sat Jan 27, 2024 11:01 am ] |
| Post subject: | voltage needed |
Anyone know what voltage is needed from the signal generator pick up coil to tell the "A" unit to fire the "B" unit. Early CDI system 1969 H1.I have an oscilloscope so can check it ok. I`ve lost spark at plugs. Testing just the "B" unit gives a REALLY GOOD fat blue spark so that`s ok. |
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| Author: | ALTERED IMAGE [ Sat Jan 27, 2024 12:08 pm ] |
| Post subject: | Re: voltage needed |
1.4v positive |
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| Author: | Jim [ Sat Jan 27, 2024 1:29 pm ] |
| Post subject: | Re: voltage needed |
Actually, the early H1 CDI unit is triggered by the negative going part of the pickup coil's output pulse. Not much more than a volt or so is required. The CDI unit's input will clip that pulse, so the shape of the pulse will be different when connected to a working CDI unit from what it looks like on a scope while disconnected. |
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| Author: | 0120raptor [ Sat Jan 27, 2024 4:41 pm ] |
| Post subject: | Re: voltage needed |
Jim wrote: Actually, the early H1 CDI unit is triggered by the negative going part of the pickup coil's output pulse. Not much more than a volt or so is required. The CDI unit's input will clip that pulse, so the shape of the pulse will be different when connected to a working CDI unit from what it looks like on a scope while disconnected. I`ll check the shape and voltage tomorrow but this will have to be from the kickstart as I`ve no spark. Do the magnets go weak ? |
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| Author: | Jim [ Sat Jan 27, 2024 9:23 pm ] |
| Post subject: | Re: voltage needed |
I doubt it. The old beat up alternator assembly I have had a very strong magnet in it. Does yours seem to attract steel stuff? You should get way over a volt with a kick. |
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| Author: | ALTERED IMAGE [ Sat Jan 27, 2024 10:54 pm ] |
| Post subject: | Re: voltage needed |
Jim wrote: Actually, the early H1 CDI unit is triggered by the negative going part of the pickup coil's output pulse. Not much more than a volt or so is required. The CDI unit's input will clip that pulse, so the shape of the pulse will be different when connected to a working CDI unit from what it looks like on a scope while disconnected. Thanx Jim. Is it negative or zero crossing? cliff |
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| Author: | Jim [ Sun Jan 28, 2024 8:02 am ] |
| Post subject: | Re: voltage needed |
If I remember right, it triggers somewhat after going negative. |
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| Author: | 0120raptor [ Sun Jan 28, 2024 10:43 am ] |
| Post subject: | Re: voltage needed |
Checked today. I have 2 volts at least P to P. Nice solid waveform.So pickup and magnets are ok. I tried following Starfires check list for the "A" unit from the Kawasaki Triple Resource site. I might be mistaken but it seems wrong to me. Line 5 says "touch the yellow wire to gray wire unit "A". This is basically connecting input to output. Seems illogical. Is it right ? I haven`t tried this yet in case I pop something. Later on under line 6 it says "connect yellow to gray unit "B". But "B" isn`t connected to anything at this stage. I`ve tried 2 used unknown "A" units plus my own and still no spark. In desperation I connected up a Boyer system and bike fired first kick. What I don`t understand is why can`t we just fit a CDI unit from another bike. All it needs is to be compatible with the signal from the pick up and be able to generate enough sparks to reach redline. |
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| Author: | Jim [ Sun Jan 28, 2024 1:26 pm ] |
| Post subject: | Re: voltage needed |
The early H1 uses a 12v powered CDI system. It has to be able to fire nearly 500 sparks per second (10,000 rpm), and that limits the choices. CDI units I've tested for applications like 2-stroke scooters can't make sparks that fast. You could use 3 scooter units if you used an H2 type signal generator that has three separate outputs. Maybe there's another 12v system out there somewhere that can make 500 sparks per second. As far as I remember, the test procedure you have is valid. |
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| Author: | 0120raptor [ Sun Jan 28, 2024 1:41 pm ] |
| Post subject: | Re: voltage needed |
Jim wrote: The early H1 uses a 12v powered CDI system. It has to be able to fire nearly 500 sparks per second (10,000 rpm), and that limits the choices. CDI units I've tested for applications like 2-stroke scooters can't make sparks that fast. You could use 3 scooter units if you used an H2 type signal generator that has three separate outputs. Maybe there's another 12v system out there somewhere that can make 500 sparks per second. As far as I remember, the test procedure you have is valid. I had a feeling the sparks / minute was a problem. That`s probably why the main capacitor in the "B" unit is only 800 nanofarads compared to other cdi units at nearer 3 microfarads so it can charge quicker.. |
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