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Post by sandy on Oct 24, 2020 17:40:26 GMT
Tried to start my latest purchase today, turns over well on starter but no spark on either plug.
Battery is fully charged Known good coil fitted, still no spark Known good CDI unit fitted, still no spark Disconnected black/white wire from kill switch, no spark Fitted known good plugs, no spark
Tested generator with multimeter
Green to white = 172 ohms Blue to white = 5.3 ohms Green to blue = 172 ohms Green to link = 15.8 ohms
All within tolerances from honda manual.
I'm running out of ideas now, anyone have any ideas where to try next?
Shouldn't be related, but while I was at it I checked out the regulator / rectifier unit. I think it's dead, getting high resistance both directions across the diodes
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Post by comstar on Oct 25, 2020 2:17:28 GMT
Hi Sandy,
If the generator is good and all else is good then I am suggesting a wiring or earthing fault. Is this happening on the bike that has currently had the frame painted, WTD?
You may actually have to try a replacement loom as there could be a breakage somewhere or the new paint might be stopping a good earth. Are you also 100% sure that the CDI is good and is the same type and correct for the 250/400, the 250N being a nippondenso item and the 400N being Hitachi? They are different. Also the coil and associated leads/caps I am assuming are 100% known good as you state? just double checking..
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Post by sandy on Oct 25, 2020 7:24:23 GMT
Hi Sandy, If the generator is good and all else is good then I am suggesting a wiring or earthing fault. Is this happening on the bike that has currently had the frame painted, WTD? You may actually have to try a replacement loom as there could be a breakage somewhere or the new paint might be stopping a good earth. Are you also 100% sure that the CDI is good and is the same type and correct for the 250/400, the 250N being a nippondenso item and the 400N being Hitachi? They are different. Also the coil and associated leads/caps I am assuming are 100% known good as you state? just double checking.. Hi, I was thinking along the same lines. The problem is with the S reg bike, WTD was running fine before I stripped it down last month, so is a perfect source of known good parts as it's the same age. I will spend today doing point to point testing of the loom, but most of the ignition system is separate from the main loom and has either been confirmed Good or replaced. I will whip off the genny cover as well just in case there is something obvious there. I did rule out an earthing issue as the starter is fine, so I assumed that the engine earth was good. I will check everything now as I don't know the history of the bike, could be anything. Thanks for the input, good to know the support is there.
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Post by comstar on Oct 25, 2020 7:38:46 GMT
Keep us informed.
I am sure we will sort it all together.
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Post by sandy on Oct 25, 2020 9:16:59 GMT
I must have been a bit tired last night, I just looked at the figures I wrote down. Generator green to white wire tolerance is well over the 172 Ohms I wrote down last night. Checked again just now and that is what it reads. Checked a couple of my other SDs and both have around 300 Ohms, could be the problem?
I Suspect someone knew this, the rotor bolt was not even tight. Now I need to get the rotor off, don't have the correct puller.
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No spark
Oct 25, 2020 9:32:09 GMT
via mobile
Post by andy1kenobe on Oct 25, 2020 9:32:09 GMT
I think I read that the pool filter bolt will fit. I may be totally wrong here but sure someone will come along and correct me. I can't remember if I have a puller for it either. I did have the thing off on my 250 way back but how eludes me now!
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No spark
Oct 25, 2020 9:33:13 GMT
via mobile
Post by andy1kenobe on Oct 25, 2020 9:33:13 GMT
That should read oil filter bolt. Damn predictive text. 🤣
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Post by sandy on Oct 29, 2020 15:25:16 GMT
Bought a bolt of the correct size. Rotor came off easily. Couldn't say the same for the 3 very experienced stator screws. They were very messed up, rounded off and been chiselled off in the past by the look of it. I got them off eventually and have removed the stator assembly. I should be getting a replacement assembly tomorrow, fingers crossed it's ok and the stator was the problem.
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Post by sandy on Oct 30, 2020 14:49:39 GMT
Got my replacement generator today, well a whole engine bottom end actually. Replaced the generator and now have 2 big fat sparks, case closed.
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Post by comstar on Oct 30, 2020 21:34:31 GMT
Got my replacement generator today, well a whole engine bottom end actually. Replaced the generator and now have 2 big fat sparks, case closed. Great news, very pleased for you, how satisfying.
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Post by Chris P Duck on Nov 2, 2020 17:45:57 GMT
I know you have sorted the issue but here is something related that you and others may find useful regarding misfiring.
Its always best to check out the ign system when this occurs ( for any reason ) by using those relatively inexpensive red neon plug caps, that flash when HT passes thru them.
On start up the flash may be very dim and weak, rising in intensity when the engine starts and growing in intensity as revs rise ( rate of change ) as the ACV output increases with revs.
Yes, a converter will have to be made so they "connect to the bikes plug caps ", but well worthy the effort as the flashes can be seen in real world conditions whilst riding, particularly at night.
If the engine misfires, the flashes stop.
A misfire due to the plugs "oiling up", due to a weak spark..........
HT coils may pass all the bench tests but still allow a misfire to happen........
So, to prevent hair loss ( the classic engine will not rev over 4 to 5 k revs classic, pointing to a fuel problem ( surging ) or possible HT coil breakdown ) use the red neons.
Rule the ign system in or out early.
Wobbly HT leads into the HT coil indicate a problem as they are glued in.
If you don't have any red neon plug caps , ask santa for a stocking filler. Well worth the money
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