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Post by lcstu on Aug 13, 2021 7:57:23 GMT 1
Carb has been cleaned and electrical components swapped for known working but still back firing when trying to start. It will fire when kicked over but not continue to run and the backfires through exhaust.
Only thing that hasn’t been changed is stator. Thinking it could be timing issue.
Any other ideas?
Cheers
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Post by yamman1066 on Aug 13, 2021 10:16:03 GMT 1
CDI
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Post by lcstu on Aug 13, 2021 17:29:08 GMT 1
Changed it and still the same
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Post by steeley on Aug 14, 2021 17:43:57 GMT 1
Hi , have you had the ignition rotor off to check the Woodruff key . If this has sheared the rotor will be in the wrong place/ timing .
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Post by lcstu on Aug 15, 2021 10:04:28 GMT 1
Hi , have you had the ignition rotor off to check the Woodruff key . If this has sheared the rotor will be in the wrong place/ timing . Hi, haven’t done this yet. Will look at this next. Cheers |
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Post by steeley on Aug 15, 2021 17:17:05 GMT 1
Hi , have you had the ignition rotor off to check the Woodruff key . If this has sheared the rotor will be in the wrong place/ timing . Hi, haven’t done this yet. Will look at this next. Cheers Hi , i would invest in a proper puller to get the rotor off and not be tempted to use a 3 legged puller . |
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Post by jorjasfather on Aug 18, 2021 13:19:48 GMT 1
If the woodruff key has sheared when you take nut off it will just pull of
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Post by curlyrambo on Sept 19, 2021 11:49:54 GMT 1
I have exactly the same problem with mk3 dt125lc ypvs.
Getting fed up of it now
It does the same with two different carbs set to default settings.
It has run twice and it was fine
Then the drama starts again.
Think this will be stripped for spares if it goes on much longer
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Post by simon998 on Sept 19, 2021 13:09:28 GMT 1
Sounds like when my 125lc had an airleak in the crankcases
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Post by curlyrambo on Sept 19, 2021 14:26:23 GMT 1
Cheers, I will pull motor out and change seals
Waiting for puller to arrive 😉
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Post by curlyrambo on Sept 19, 2021 14:35:19 GMT 1
Sounds like when my 125lc had an airleak in the crankcases Mine tries to fire but won't keep running What symptoms did yours hsve ? |
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Post by muttsnuts on Sept 20, 2021 12:15:58 GMT 1
I have exactly the same problem with mk3 dt125lc ypvs. Getting fed up of it now It does the same with two different carbs set to default settings. It has run twice and it was fine Then the drama starts again. Think this will be stripped for spares if it goes on much longer its most likely the CDI, the MK3's are known for having a crap CDI, changed several this year to ignitech units |
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Post by curlyrambo on Sept 20, 2021 13:44:51 GMT 1
I have exactly the same problem with mk3 dt125lc ypvs. Getting fed up of it now It does the same with two different carbs set to default settings. It has run twice and it was fine Then the drama starts again. Think this will be stripped for spares if it goes on much longer its most likely the CDI, the MK3's are known for having a crap CDI, changed several this year to ignitech units |
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Post by curlyrambo on Sept 20, 2021 13:47:33 GMT 1
Hi bud , are the ignitech units easy to fit?
Does it work with my separate pv controller?
Atb j
Is there a UK supplier?
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Post by muttsnuts on Sept 20, 2021 15:55:59 GMT 1
Hi bud , are the ignitech units easy to fit? Does it work with my separate pv controller? Atb j Is there a UK supplier? The ignitech replaces both the CDI and PV controller, and its fully programmable, its fairly easy to fit, but isn't plug and play, requires some electrical/wiring knowledge/ability I can supply them if required |
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Post by simon998 on Sept 21, 2021 8:16:39 GMT 1
Oh I thought you'd replaced the CDI Box already. We've hd to chnge the CDI boxes in all 3 of our 125lc's and a mate had loads of bother with his YPVS one recently. That'd be my first call.
I've had success with putting them in the oven at a low temperature (50-80 degrees) to reflow the connections in the CDI Box, you could try that and if it works you know it's the CDI at fault.
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Post by guiri on Sept 21, 2021 19:31:38 GMT 1
One thing that gets overlooked but is very rare, I have seen a broken or stuck reed petal cause similar problems..
Also. have you defo checked the replacement parts on another bike.. as said above.. the cdis are shite..
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Post by cinder on Sept 26, 2021 8:53:05 GMT 1
Gennys seem to cause a lot of problems these days .get your readings checked
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Post by chrisg on Sept 27, 2021 14:29:43 GMT 1
Try the simplest thing first. New plug. These has caused numerous headaches over the years especially fake NGK.
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Post by museumman on Oct 3, 2021 1:22:14 GMT 1
Woodruff keys on good examples don't sheer or fall out. (bodged bikes, or with crap worn parts would be the cause of a slipping rotor and the tapers will need sorting) By default I now do the below to all originals I import, even if they look mint. I've done almost 1 bike per month in the last year. I find nice examples mostly because their Cdis have failed forcing them to get shoved away for years. New Ignitech Cdi - Just 2 wires to fettle if you order it to your model, will come with a plug for the others. New NGK resistor type plug cap, snipping of a few mill on HT lead New Champion spark plug, or other brand to rule out the dodgy NGKs as chrisg mentions aboveNew Yuasa acid battery (quality new because Ignitech relies on it) New eyelets soldered on to main earth in loom, checking for greening or blacking on the copper If stator coil 1 has gone there will be no spark and it wont fire Stator coil 2 usually reads lower than book, outside of spec, but they still seem to run ok. I have a NOS one at 35 Ohms (book says 65). However the Ignitech now bypasses it. If left crank seal has gone these bikes usually fail to start. I've never heard one backfire. I also program the new Cdi with the curve from the Yamaha book, they run ok with the default curve supplied. Ideally you should visit Muttsnuts for a unit, he posted above, have the curve optimized on the dyno to suit your bike and he can tweek anything else. I fit Ignitech in the tool kit area. The cut black wire can be earthed via a switch to select a 2nd stored curve.
The green wire goes to kill switch female bullet (Red/Black on loom) The Red wire goes to the ignition switched 12 volt (Brown, which can be picked up locally)
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