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Lighting and Electrical Things that go ZOT! Ignition components, batteries, lighting and accessories

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Old 03-17-2015, 10:12 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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Default My official testing of several different aftermarket CDIs

I got really sick of all the BS about who's CDI is best.... So I've been testing several different aftermarket CDIs (head to head) for highest spark voltage & total advance degrees at full throttle.

There's a lot more testing to be done but my first results are posted on my VMB/facebook page.

You can click here & see what I have so far.

https://www.facebook.com/VeniceMotorBikes
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Old 03-17-2015, 10:21 PM
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Venice Motor Bikes Venice Motor Bikes is offline
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This is my home made testing bench... I'm using a coil voltage tester for the CDIs along with a timing light & a fixed degree wheel bolted to the crank to check the spark advance.

I'm also using a digital voltage tester on several different magnetos.



image-838428865.jpg

Below is the largest spark I was able to make... (It came from one particular stock chinese CDI)... It is a whopping 20 full turns!!



image-143721470.jpg
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Last edited by Venice Motor Bikes; 03-17-2015 at 11:20 PM.
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Old 03-17-2015, 10:22 PM
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Here's some of the different aftermarket CDIs that I tested with the results...

*edit*>>> The numbers posted are the total advance degrees @ 3000 RPM, & the 'number of turns' is the total outward turns on the coil voltage tester.

All the CDIs that I tested (even the stock Chinese black boxes) have a advance curve of roughly 25-30 degrees.

Most of the stock Chinese boxes maxed out around 5-10 turns, (but one particular Chinese box maxed out at a whopping 20 turns)!!!

My 12v timing light was having a bit of trouble reading the 6v sparks at low RPMs, but I was able to see quick flashes of where the timing curves started.

image-3758718735.jpg



image-3150630639.jpg



image-4289475941.jpg



image-386973151.jpg
Gas Bike just re-named this the 'Super Rocket' CDI


image-504095877.jpg
Gas Bike just re-named this the 'Thunder' CDI.
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Last edited by Venice Motor Bikes; 03-20-2015 at 10:33 AM.
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Old 03-17-2015, 10:32 PM
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Default Re: My official testing of several different aftermarket CDIs

From my testing, the two GasBike CDIs have the exact same spark power as the HD Lightning, (& also the same retarded timing at 10 degrees BTDC).
These would work best for a really 'hot' running (high revving) engine with a large expansion chamber pipe... (the 'Super Rocket' is a killer deal)!!

The Screaming Roo has the same spark power as the first three, but has the same spark advance as a stock Chinese CDI (20 degrees BTDC).
This would be the best choice for a moderately modified street engine.

The Jaguar CDI has the weakest spark (but still way stronger than most stock CDIs), & the timing is in between the others at 15 degrees.
This is a good choice if you want to change the timing curves for use on different engines.
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Last edited by Venice Motor Bikes; 03-17-2015 at 11:16 PM.
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Old 03-17-2015, 11:03 PM
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Default Re: My official testing of several different aftermarket CDIs

Why thank you, VMB.

It's good of you to investigate, document and share your findings. It could be useful.
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Old 03-18-2015, 02:35 PM
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Default Re: My official testing of several different aftermarket CDIs

Yes, thanks for getting into something that there is little hard info on! My question is are these values ultimate advance starting from a lower degree base point or is this a fixed value?, if variable where does the curve begin?
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Old 03-18-2015, 03:33 PM
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Default Re: My official testing of several different aftermarket CDIs

Interesting finds! So there is an advantage of these CDI's over a stock unit and it's not all snake oil?
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Old 03-18-2015, 05:07 PM
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Default Re: My official testing of several different aftermarket CDIs

Norm,
Are you planning some actual road testing in addition to the bench? Timed/speed trials over a specific distance? It's okay to know voltages and advance curves but I'd be interested in seeing real world results along with them.

Same engine, same bike, same rider, same fuel, tire inflation, etc. Same engine temperature as well as the same weather conditions. Humidity and temperature will play into performance as you well know.

Tom
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Old 03-18-2015, 05:13 PM
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Default Re: My official testing of several different aftermarket CDIs

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Originally Posted by 2door View Post
Norm,
Are you planning some actual road testing in addition to the bench? Timed/speed trials over a specific distance? It's okay to know voltages and advance curves but I'd be interested in seeing real world results along with them.

Same engine, same bike, same rider, same fuel, tire inflation, etc. Same engine temperature as well as the same weather conditions. Humidity and temperature will play into performance as you well know.

Tom
Might be worth while to just set up a bench test using the same speedometer on the rear wheel so you don't have other things tainting the results like humidity, temperature, and wind fluctuations
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Old 03-18-2015, 11:52 PM
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Default Re: My official testing of several different aftermarket CDIs

Quote:
Originally Posted by YesImLDS View Post
Might be worth while to just set up a bench test using the same speedometer on the rear wheel so you don't have other things tainting the results like humidity, temperature, and wind fluctuations
Still no substitute for real world road testing... there's one important factor missing from bench testing.... engine load. It needs to be able to perform under load in equal conditions by making each run at a specific distance then check the speed or time it takes to get from point a to point b then the test needs to be done going this distance then on the return so you record both directions then average the results to compensate for variables of unlevel road, wind, etc... the temperature isn't a huge factor and wont change a whole lot between runs enough to make a difference... unless a cold front is on its way... humidity can also remain the same long enough to run several tests.
several units can be pres installed on a single bracket and swappdd out either by switches to select which unit will be active or unplugging one andnplugging in the next so all the runs can be done in a very short timeframe like under an hour to test 5 or 6 units on a 1/2 mile to 1 mile out and back run.
the quickest way to switch which unit is active would be by wiring them all to a common plug and using either a selector rotary switch or a switch on each unit and turn off everyone except the one intended for each run, then its just a flip of the switch and the next cdi is active and all others are inactive. A row of toggle switches or a single rotary selector would make switching units take just a matter of seconds, and with a rotary selector you could switch from onento the next without even shutting off the engine.
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