CDI units. what are they all about anyway? By hellspigeon (Read 867 times)

[Moat]

Nov 22, 2013 13:18:06 GMT -6 Alleyoop said:

The reality is a motor can make more power if it fires just a hair after top dead center.

Umm, the reality is a motor will run like poo if it fires "just a hair after top dead center" - if you could even get it started, that is. Virtually all spark-fired engines ignite the mixture well before TDC - typically 8 to 20 degrees BTDC @ idle, and 25 to 45 degrees BTDC at speed. Actually, the majority of the fuel is already burned before the piston even reaches TDC. The reason for spark advance is that it takes time for the mixture to burn.

In general, the more spark advance (degrees BTDC), the higher the peak combustion pressures produced - and therefore more torque. The limit to how far spark can be advanced is determined by detonation (not pre-ignition, which is something different) - in which case power drops off dramatically (followed shortly by molten/broken engine parts).

Bob

[Moat]

Nov 22, 2013 21:09:21 GMT -6 Alleyoop said:

... but I did notice his scoot was to far retarded to start off His timing was almost on the "F" when it should be on the "T".

"F" stands for Fire, "T" stands for Top Dead Center. His idle ignition timing should have been on the "F", and not the "T" (which would have been waay too retarded).

Bob

[hellspigeon]

Thanks for the advice guys. I got the extra dosh laying around, so I'm gonna try the Naraku CDI. I'll report back in a few weeks and let yall know how it's doing.

[sitticuss]

Cool i for one am curious to see if it makes a difference for you.