On my track 3XV I use a 'smoothing condenser' from a TZ250 in place of the battery. It weighs only a hundred grammes or so and works a treat (obviously you have no power with the motor off).

Perhaps of more interest to you Honda types is the fact that the CRM250 uses a very similar condenser in place of a battery. I guess there are different types with different ratings and it'd be ideal to find one that was rated ideally to work with the NSRs electrics. That said, I'd be very tempted to try one from a CRM though to see how you go...

When I had an NSR though, I remember it was quite hard work to start with anything other than a fully charged battery, so this might be a stumbling block for anyone wanting to do away with the battery on the Honda? You would almost certainly be fine to replace it with the smaller, lighter 3XV battery though. I recently replaced the much bigger and heavier trad' type battery on my 3MA with one with no problems.

Hope that's of interest

Wb