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Cheap Ebay CDI units any good?


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On ebay you can buy cheap CDI units, sure they are listed as for small bikes & the ignition curve may be off, but has any one tried one?

using one & having one as a spare for £14, suits me if they are any good?

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I'd say it depends, but for most bikes I'd look for a good used from eBay as a spare.

The cheap performance CDI units for Chinese scooters and pits work well, and I haven't had one fail yet, but I also don't ride them 100 miles into back country. (I'd kind of like to try though)

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I might just buy one & check the advance curve, the " if its chinese its  crap" is not always true, they are more than capable of making good products....

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26 minutes ago, pxr5 said:

I might just buy one & check the advance curve, the " if its chinese its  crap" is not always true, they are more than capable of making good products....

How are you going to check the advance curve? Many engines (high performance dirt bikes for example) do not have the crank position sensor located at the firing point. They are located at a design wise ideal location.

Then based on voltage rise and multiple sensor signals (one or two week, one strong 'fire') the CDI determines crank position and then when to actually fire off the spark. They combine that information with TPS numbers to vary the curve, if it actually exists. A lot of units have a 'in neutral' retard and an 'in gear' spark advance with the closed throttle, then once the throttle opens, many just have a set advance. The good ones use RPM and throttle position to add or remove advance.

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this is on a 2 stroke Cr500, so just make a pointer & use a strobe light.

I note your a mod', every time I go to log on here, I have to reset my pass word, do you know why?  thanks

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1 hour ago, pxr5 said:

this is on a 2 stroke Cr500, so just make a pointer & use a strobe light.

I note your a mod', every time I go to log on here, I have to reset my pass word, do you know why?  thanks

A strobe will only tell you if the timing is right, that assumes it starts at all. You'll need to map all RPM and timing positions to determine if and when the CDI has advance capabilities.

Post a Q about your PW problem here:

https://thumpertalk.com/forums/forum/319-site-usage-functions/

 

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