What abotu the older Bikes?

The 2-strokes like your CR are technically designed for closed courses, so they normally don't have things like snorkels for water crossings/noise control or other types of power robbing devices. I would check all the normal maintenance items, silencer is packed, jetted properly, reeds in good shape, power valve functioning etc. for power gains. The only free mod I can think of is advancing the timing, but this might require high octane fuel/race gas if you advance it alot.