I have a CB250RSA that I use as a sand racing bike. As it is a race bike I have taken the charging system/battery off the bike. The alternator output originally had 3 x yellow wires to the charging system - now junked - and a white and a blue wire direct to the CDI. The bike has run fine like this for a couple of years.

I would like to run the CDI with battery power as it means I can lose the stator/flywheel and the associated weight. It also means there is one less moving part to go wrong.

I established that the bike would run fine with only the blue alternator output wire connected to the CDI so what the white wire does is a mystery to me. (The pulse generator wires and CDI earth are still in place, the ignition switch wire is connected to a lanyard cut out.)

I connected the blue CDI input to 12v DC battery and got one spark only.

I re-connected the blue CDI input to alternator power = no sparks.

Connected a different CDI unit to the alternator power (blue wire only) = sparks again.

So I have killed 1 x CDI and am not much wiser The things I had read previously indicated that getting enough power from a battery to power a CDI would be a problem - I guess not in this case. I know a guy who had run this way on a 650 Bros, an SLR 650 and an XL500.

If any one has any ideas they would be appreciated.

Thanks,

Russ