fredswat
L plate rider.
Two Stroke lover forever
Posts: 23 
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Post by fredswat on Oct 28, 2020 9:14:09 GMT 1
I have a "no spark" issue on my 4LO that I have been rebuilding . When I last used it about 10 years ago it had sparks . I recently have done some work on it . New crank, fitted indicators , tidied up some bullet connectors by fitting proper multi plugs. I have got to the point where I am ready to try to start it only to discover it has no sparks. I am going to check out the continuity of the wires. I noticed on the wiring diagram it shows a "Frame ground" Does anyone know where this goes from and to? I can't see it. I had a similar issue on the H1 I rebuilt a while back where I chased through the whole electrical system replacing everything at huge expense only to find I had missed off an earth from the engine to the frame. Sorry can't seem to paste image of the wiring diagram at the moment ![]() |
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Post by rigga on Oct 28, 2020 9:16:16 GMT 1
Negative terminal on battery to a stud/bolt by the coils.
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fredswat
L plate rider.
Two Stroke lover forever
Posts: 23
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Post by fredswat on Oct 28, 2020 10:15:41 GMT 1
Negative terminal on battery to a stud/bolt by the coils. Does that mean there should be two negative connections to the negative terminal on the battery? |
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Post by Shytalk on Oct 28, 2020 16:43:41 GMT 1
Negative terminal on battery to a stud/bolt by the coils. Does that mean there should be two negative connections to the negative terminal on the battery? No, there is just one terminal connection but the loom splices in multiple earths as it runs around the bike. |
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Post by rigga on Oct 28, 2020 18:10:19 GMT 1
Yea one black ring terminal bolted to the frame by the coil, but in the loom it splits to the various circuits that require a earth.
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Post by reedpete on Oct 28, 2020 18:36:21 GMT 1
Fred, I‘m assuming you have linked the question about the grounds to the fact there’s no spark.....
FYI, no battery or earth connections are required to get sparks.....
And if I recall, you can connect up most of the related circuit without needing the loom. Only connections that run in the loom are the orange and black that go from the cdi to the coil.
So you can pretty much plug it all together and see what’s what.
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fredswat
L plate rider.
Two Stroke lover forever
Posts: 23
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Post by fredswat on Oct 29, 2020 6:17:11 GMT 1
Fred, I‘m assuming you have linked the question about the grounds to the fact there’s no spark..... FYI, no battery or earth connections are required to get sparks..... And if I recall, you can connect up most of the related circuit without needing the loom. Only connections that run in the loom are the orange and black that go from the cdi to the coil. So you can pretty much plug it all together and see what’s what. Cheers that's really useful. I did ask an earlier question regarding the wires from the generator/alternator. When I replaced the bullet connectors that had been fitted in the bikes distant past with multi plugs, I didn't mark the order the three white wires were that go to the Regulator rectifier from the generator. Someone said it didn't matter. Is this true? Any easy tests to understand why it's not getting sparks now? that you can think of? |
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Post by Tobyjugs on Oct 29, 2020 8:05:10 GMT 1
It doesn't matter when it comes to the white wire.
I tend to fit an earth wire from the engine to the chassis on anything I build wether car or motorcycle. Mostly as a precaution against bad earthing.
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Post by reedpete on Oct 29, 2020 10:35:03 GMT 1
Fred, again. None of those white wires are involved in making sparks...
As for quick test.
Disconnect the black white wire going into the cdi, leave all others connected and see what happens...
Black white is the ‘kill switch’ circuit . Bizarrely the design is such that it works backwards, so disconnected it allows the cdi to function.
Release it out of the connector is best way if you have suitable or improvised tool.
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Post by bare on Nov 1, 2020 0:25:48 GMT 1
Factory Yama wirings All thru the 80's was Sad. They seemed to economise on Ground wires.
As evidence slit open Any yama loom from that era to witness the resulting overload melted black wires.
Klever to add (in the Very least) a ground wire from the battery directly to a nearby Frame bolt.
Also adding a similar ground wire from the engine to the frame... which may or may not help.. but it surely won't hurt.
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