CDI Unit - What causes failure?

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CDI Unit - What causes failure?

Postby Scooterbrad » Tue Oct 23, 2018 6:14 am

Hi all. I purchased an 2005 LML a year ago. I did not start, but once the CDI unit was replaced, it ran like the clappers. Now the scooter just cuts out as soon as it warms up. The mechanic says CDI unit needs to be replaced (again). '

What could be the cause of the CDI unit failure? Surely after a year it should not need replacing? There must be a root cause that is destroying the CDI (?)

Any help?
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Re: CDI Unit - What causes failure?

Postby rob h » Tue Oct 23, 2018 2:50 pm

Difficult one, I had a worn stator plate causing cut out at heat, voltage regulator faulty can break down under heat. Cheap untested e bay parts are an issue, dealer ones are dearer but you have some come back. You are sure it is electrical, not fuel line kinked this can be an issue. Ceramic fail of the spark plug can do the same running well until hot, oh the joy of two strokes. Have you tried another plug when hot to check for spark. Sorry to offer more problems than solutions.
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Re: CDI Unit - What causes failure?

Postby Shaunbond » Tue Oct 23, 2018 6:54 pm

Start with the easy stuff like Rob says, plug, cap, HT lead. If you can get a replacement coil (assume that's what you mean by CDI as its odd for the LML CDI to fail) and see if it's that. It wouldn't surprise me if the LT coil on the stator is at fault.
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Re: CDI Unit - What causes failure?

Postby Scooterbrad » Wed Oct 31, 2018 12:35 pm

Thanks guys. I am still waiting for my scoot from the mechanic. I will have a discussion with him regarding the above.
Regards

BTW, this is a kick start only scooter, so no battery involved. Would this change anything you have said above?
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Re: CDI Unit - What causes failure?

Postby rob h » Wed Oct 31, 2018 1:28 pm

Not many battery only Lml star about. Principle the same, voltage generated as you kick by flywheel, this goes through voltage regulator to coil, ht lead,plug.
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Re: CDI Unit - What causes failure?

Postby rob h » Wed Oct 31, 2018 1:31 pm

Check if it did have a battery, or if original wiring is still their, not unknown for wiring to be removed, does it have an electric start!
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Re: CDI Unit - What causes failure?

Postby Scooterbrad » Wed Oct 31, 2018 3:26 pm

hi Rob, no this is definitely a kick start only. I have had 6 of them, three of which I still own. Never had a electric start LML.
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Re: CDI Unit - What causes failure?

Postby Leigh » Thu Nov 01, 2018 1:21 pm

Hi Brad,

If you're talking about the LML coil (and I'm assuming you are from this point on), there is a very weak point on the top of the coil where a small wire is soldered to a metal tab. The plastic coil casing comes loose from the metal bracket which bolts to the engine. The casing then moves and the solder breaks. By far the best solution if to convert your scooter to run on the Vespa style Ducati CDI. They're more expensive but far more reliable!

Cheers,

Leigh.
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Re: CDI Unit - What causes failure?

Postby Scooterbrad » Thu Nov 01, 2018 3:09 pm

Leigh wrote:Hi Brad,

If you're talking about the LML coil (and I'm assuming you are from this point on), there is a very weak point on the top of the coil where a small wire is soldered to a metal tab. The plastic coil casing comes loose from the metal bracket which bolts to the engine. The casing then moves and the solder breaks. By far the best solution if to convert your scooter to run on the Vespa style Ducati CDI. They're more expensive but far more reliable!

Cheers,

Leigh.


Thank you Leigh. I will certainly check that weak spot you mention. I will investigate the CDI option you mention. Not sure if we can get that here in South Africa, but I will search.
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