02 trx 400ex no spark

8571 Views 7 Replies 3 Participants Last post by timpersson, Jun 14, 2013

timpersson

Discussion Starter · Jun 12, 2013

I recently purchased and installed an aftermarket stator from calric in an 02 Honda trx 400ex. I am not getting a spark from the coil. It appears that all the voltages are within the ranges stated in the shop manual. I logged the signals while cranking of the pulse generator and alternator at the cdi plug and the signal to the coil with the cdi which can be seen here Untitled Document This is a know good cdi box and confirmed no continuity between the kill(black/white) and ground. I was wondering if anyone has an idea why the cdi is not firing the coil or could point me in the right direction. Thank you.

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400exRacer

· #2 · Jun 12, 2013

Check the crank positioning sensor

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timpersson

Discussion Starter · #3 · Jun 12, 2013

It doenst show a crank position sensor but it does have a pulse generator which would be the same thing i guess. It is part of the stator wiring and is one of the parts that I replaced. The manual shows the pulse generator should have a max voltage of 0.7 volts. i scoped it here

Text Oscilloscope Technology Line Electronic device

and it has a positive .5v spike followed by a -1v spike which you would think would be enough to signal the cdi.

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400exRacer

· #4 · Jun 13, 2013

Is that when your turning over the motor

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Here 2 help

· #5 · Jun 13, 2013

Did you have spark before installing the Caltric stator?

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timpersson

Discussion Starter · #6 · Jun 13, 2013

Yes, that was while cranking... The pulse generator was the issue. I soldered the old pulse generator onto the caltric assembly and it gave a 4volt pulse and sparked the coil. It was a frustrating problem since the replacement was giving a pulse that was within the limits of the shop manual. Also the old stator was badly mechanically damaged from a screwdriver bit the previous owner left in the stator housing so i was thinking that may have caused a short which damaged the cdi box.

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Here 2 help

· #7 · Jun 14, 2013

I worked on a 400EX once that the only part that tested good was the one that was bad.

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timpersson

Discussion Starter · #8 · Jun 14, 2013

Here 2 help said:
I worked on a 400EX once that the only part that tested good was the one that was bad.

what makes it worse is there is no testing procedure given for the cdi box. Only replacement instructions. Something like unplug, remove, replace, replug. So obviously if everything is testing good into the cdi box you are going to assume that is the problem. i wonder how many good cdi boxes have been replaced over the years.

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