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James H

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Confused
Dec 10^th, 2016 at 9:34am

I hope someone can shed some light on this. This is a capture from 1 cylinder on a waste spark ignition. The engine appears to run fine but I am confused as to why the firing voltage is so high unless I have my scope setup wrong. From my limited knowledge I think the rest of the pattern looks okay except the burn time is a little short. I don't see any indication that the fuel air ratio is out of the ball park. I also checked it on cranking with the plug leads grounded outside the engine via a .020" gap and the firing voltage is still high. Can anybody shed some light on this?

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Ignition_Primary___secondary.psdata (4950 KB | )

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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: Confused Reply #1 - Dec 10^th, 2016 at 9:50am James H wrote on Dec 10^th, 2016 at 9:34am: The engine appears to run fine but I am confused as to why the firing voltage is so high unless I have my scope setup wrong. James you need to select the Coloured Secondary Pos in the library. Make sure you dont select the black probe.
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James H Senior Member Picogroup Offline Bike Nerd Posts: 165 Waterloo Ontario Canada Gender:	Re: Confused Reply #2 - Dec 10^th, 2016 at 9:58am Errr. Duh, Can't believe I missed that, If it seems impossible it is. lol
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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: Confused Reply #3 - Dec 10^th, 2016 at 10:03am This is where the Probe is Try the scope set up at 500ms/Div and the Sample Interval set at 6MS This will give you lots of time to see the changes in air fuel ratio across the plug gap over time.
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James H Senior Member Picogroup Offline Bike Nerd Posts: 165 Waterloo Ontario Canada Gender:	Re: Confused Reply #4 - Dec 10^th, 2016 at 10:49am Thanks Mike. There is hope yet. Does this all look normal to you?
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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: Confused Reply #5 - Dec 10^th, 2016 at 10:55am James H wrote on Dec 10^th, 2016 at 10:49am: Thanks Mike. There is hope yet. Does this all look normal to you? First of all turn the current probe around on the wire you have selected so as to see the current rise.
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James H Senior Member Picogroup Offline Bike Nerd Posts: 165 Waterloo Ontario Canada Gender:	Re: Confused Reply #6 - Dec 10^th, 2016 at 11:06am I figure it was the current that the coil was drawing so I selected it as being a negative.
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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: Confused Reply #7 - Dec 10^th, 2016 at 11:06am How about this suggestion
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Re: Confused
Reply #8 - Dec 10^th, 2016 at 11:59am

James H wrote on Dec 10^th, 2016 at 9:34am:

I hope someone can shed some light on this. This is a capture from 1 cylinder on a waste spark ignition. The engine appears to run fine but I am confused as to why the firing voltage is so high unless I have my scope setup wrong. From my limited knowledge I think the rest of the pattern looks okay except the burn time is a little short. I don't see any indication that the fuel air ratio is out of the ball park. I also checked it on cranking with the plug leads grounded outside the engine via a .020" gap and the firing voltage is still high. Can anybody shed some light on this?

I would agree and feel the burn time is borderline short in the capture you posted here in the opening post.

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N.B.S. Dilly Dilly! FJB

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James H Senior Member Picogroup Offline Bike Nerd Posts: 165 Waterloo Ontario Canada Gender:	Re: Confused Reply #9 - Dec 11^th, 2016 at 5:09am Thanks to both for the tips and suggestions. I tried the invert via the math channels Mike...neat
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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: Confused Reply #10 - Dec 11^th, 2016 at 6:33am James H wrote on Dec 11^th, 2016 at 5:09am: Thanks to both for the tips and suggestions. I tried the invert via the math channels Mike...neat That's great. Oh by the way there are a lot of Mikes on the forums but only one Mick
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