Would using this really work?

Cylon, First off the price seems too high for that coil in my opinion. in a few secs of searching, here is the same one for 23$ instead of 41 bucks, and it does not use a ugly pill bottle for the electro junction box.

http://www.ebay.com/itm/Super-Charg...337457?hash=item3abd23b671:g:YQgAAOSwezVWuS4Z

But yes the stock CDi is probably the best and while some may disagree, most think stock is better suited for these small engines. That CDI is really just a pit bike coil I believe and the spark timing may be off for our engines. Certainly wont give 8-10 mph gains and may even run worse or the same. Anyone claiming a 10 mph without changing gearing is already suspect as throwing you total BS. Plus there are some inconsistencies from CDI to the same CDI, so its all a crap shoot on CDI performance anyhow. Too much controversy on CDIs and upgrades to them. Use the search engine to read reviews, tests, comparisons on CDIs. Some swear by the Lightning CDI?
 
Oh I forgot, on his own feedback one guy wrote this...edited due to swearing)
Cdi has no advantage over stock. Wont shop again
 
That looks exactly like a Rocket/HD Lightning CDI (pill bottle CDI). It's copied by many people and sold under many names.

Most people with a "stock" engine see a performance drop with the "performance" CDI's. Or, conversely, anyone with a modified engine, that has not gone very high on the compression.


From my experience with the HD Lightning CDI, it is designed to start retarding the timing as the engine reaches high RPM's.

If you build an engine with very high compression, it will start too loose power at higher RPM's with a stock CDI, as the ignition is too advanced. By retarding the ignition at higher RPM's this CDI allows the use of very high compression (in order to boost low end torque) while preserving top end run out ability.

With this CDI, I run my compression high enough to hit 240psi on a compression test, and the engine (when jetted properly) will still run out to 10,500 RPM's.

But a stock engine actually REQUIRES the extra ignition timing at higher RPM's, because its compression is (relatively) so low.

Here is a thread where Venice Motor Bikes did some investigative analysis of the different "performance" CDI's on the market:

http://motorbicycling.com/showthread.php?t=58455

This basically shows how much timing advance each CDI has @3000 RPM's. It seems the CDI's that have less advance @3000 RPM's are beginning the advance curve later, so that they achieve the max 25-30 degrees advance at a higher rpm. So, in essence, the CDI's are not retarding the advance curve at higher RPM's (ideally around 7,500 RPM's to coincide with peak HP), they are just starting the advance curve later, allowing the engine to hit a higher RPM before the total 25-30 degrees of advance becomes too much, and it acts like a rev limiter.

This shows that the "performance" CDI's have less initial advance, witch is not good for a low compression stock engine. It does help high compression engines reach a slightly higher RPM due to the later advance curve.


What would ultimately be best is a CDI that started with a high initial advance, near the total 25-30 degrees, and then begin to retard timing very gradually starting at around 3000 RPM's until the power peak rpm of the engine (7,500 RPM's for my race engine builds), then start pulling timing out more aggressively to allow the engine to maintain efficiency (and thus power) much further past its peak power RPM.

I have found one that meets this exact criteria, and it looks like it is a direct fit for our ignition setup, kill switch and everything.

It is a Yamaha PW80 CDI:

http://www.ebay.com/itm/152044984407

This does not require a battery or a timing pickup like most dirt bike/moped CDI's do. This makes it perfectly compatible with our set-up.

I will be testing these on my race bikes in the near future and will post the results.


Hope that helps!


Don't hesitate to ask me anything!
 
Bruce Lee said:
That is not a fire cracker---------It is a bottle of birth control pills so that after you get screwed buying his stuff ---you won't get pregnent
Click to expand...
He he he. Yep. I couldn't agree more. Snake oil, that describes most of what you see marketed as 'High Performance'.

Forget it and stick with the stock ignition. Let those who don't come here to ask buy that stuff. You did good by asking first. Hope we helped before you wasted your money.

Tom
 
Oh yeah I watch this forum often. I didn't buy it. I'm going to get the 36 tooth sprocket instead.
 
exokinetic said:
That looks exactly like a Rocket/HD Lightning CDI (pill bottle CDI). It's copied by many people and sold under many names.

Most people with a "stock" engine see a performance drop with the "performance" CDI's. Or, conversely, anyone with a modified engine, that has not gone very high on the compression.


From my experience with the HD Lightning CDI, it is designed to start retarding the timing as the engine reaches high RPM's.

If you build an engine with very high compression, it will start too loose power at higher RPM's with a stock CDI, as the ignition is too advanced. By retarding the ignition at higher RPM's this CDI allows the use of very high compression (in order to boost low end torque) while preserving top end run out ability.

With this CDI, I run my compression high enough to hit 240psi on a compression test, and the engine (when jetted properly) will still run out to 10,500 RPM's.

But a stock engine actually REQUIRES the extra ignition timing at higher RPM's, because its compression is (relatively) so low.

Here is a thread where Venice Motor Bikes did some investigative analysis of the different "performance" CDI's on the market:

http://motorbicycling.com/showthread.php?t=58455

This basically shows how much timing advance each CDI has @3000 RPM's. It seems the CDI's that have less advance @3000 RPM's are beginning the advance curve later, so that they achieve the max 25-30 degrees advance at a higher rpm. So, in essence, the CDI's are not retarding the advance curve at higher RPM's (ideally around 7,500 RPM's to coincide with peak HP), they are just starting the advance curve later, allowing the engine to hit a higher RPM before the total 25-30 degrees of advance becomes too much, and it acts like a rev limiter.

This shows that the "performance" CDI's have less initial advance, witch is not good for a low compression stock engine. It does help high compression engines reach a slightly higher RPM due to the later advance curve.


What would ultimately be best is a CDI that started with a high initial advance, near the total 25-30 degrees, and then begin to retard timing very gradually starting at around 3000 RPM's until the power peak rpm of the engine (7,500 RPM's for my race engine builds), then start pulling timing out more aggressively to allow the engine to maintain efficiency (and thus power) much further past its peak power RPM.

I have found one that meets this exact criteria, and it looks like it is a direct fit for our ignition setup, kill switch and everything.

It is a Yamaha PW80 CDI:

http://www.ebay.com/itm/152044984407

This does not require a battery or a timing pickup like most dirt bike/moped CDI's do. This makes it perfectly compatible with our set-up.

I will be testing these on my race bikes in the near future and will post the results.


Hope that helps!


Don't hesitate to ask me anything!
Click to expand...
Did anything ever come out of using a pw80 cdi? Thanks
 
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