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DT 125 LC Weak Spark?


Ollie1995
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Hi, I've got a very weak spark that comes through the spark plug cable from the CDI but only occasionally it will come through the spark plug. Me and my dad can't figure out what it is, I thought it might be a bad earth? Compression is fine. Could it be a faulty CDI?

Thanks, Ollie.

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  • Moderator

has it ever worked ollie? come on tell us a bit about it

Edit...FFS ollie you have threads all over the place about your ignition woes!! sorry but i cant be bothered to root them all out out to see whats been said and done before! I dont know why you do this...they are all ignition woes so just have ONE thread !!!!!!!!!!!!!!

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I've only posted one other thread about ignition and that was to do with getting a spark in the first place not a weak spark. On all the other forums I'm on people hate refreshing old posts. Also I thought it would help others more being a more specialised topic?

Anyway, It has never run since i've had it, I bought it as a non runner with no spark at all. I then got a woodruff key and sorted the CDI out. However the spark is weak. I know nothing about JAP bikes and CDI's etc. So I am grateful for any help.

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  • Moderator

you should look at other things before the CDI, make sure the magneto coils are within spec and also the ignition coil primary and secondary, have you got a haynes book? are the specs in there?

CDI replacement should be only when everything else is tested as oK

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Ok, so yesterday I got the bike out and did a few small checks. I measured the resistance of the coil which is meant to measure 8.5-11.5 ohms according to the haynes. However mine only measures 2.5-3.5 ohms. I'm not sure if I measured it correctly because I measured another old coil that was in the garage and that also measured 2.5-3.5. But the one on the bike seams fairly new. I also removed the generator and that seemed fine(I'm not too sure how to measure this?) Lastly, I sanded down the earthing points to the frame as I haven't used the correct ones I think? The spark is still weak but I think this has improved it a little. The spark can jump about 2mm and travel through an old Champion spark plug but won't go through the NGK?

Ollie.

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