for street you need a battery.

For track, you can use a total loss system, i.e. just a battery but no on board charging.

If the battery eliminator is a capacitor, that probably won't work as it'll discharge over time and the NSR won't start without a good battery voltage.

If you just want to save weight, buy a 1.2Ah maintenance free battery, that'll save 1-1.5kg. I use it on the track, but I of course don't use lights on a track bike.

You can also buy a lightened flywheel, so save several hundred grams.
http://tyga-performance.com/site/product_info.php?products_id=46&osCsid=4c394ea113387735662c584abc049ebf
_________________
Poul
"If Life Gets Boring, Risk It!"
MC21SE, KISS box
MC21SP, HRC box, racing loom