Motorcycle Repair: SL350 charging, current regulator, bill silver

Question
Hi Bill,
My 1971 SL-350k1 charges ok...but barely.  Running high beam with lower rpms for an extended time will result in a lower charge/dimmer neutral light and hard starting.  I know these bikes maybe were not designed to run headlights all the time like today...but I also question the numbers.
If my understanding is right...the 35 Watt front bulb, and the 7 watt rear could have me running 42 watts...which would need 3.5 Amps.  My manual says it puts out up to 2.5 Amps at 5,000 RPM  and under 4 Amps at 10,000 RPM.
Am I right with this?  and is it just the way it is  that this bike will never be a robust charger?   Ive done all of the basics, checked the recitfier, regulator...I actually replaced the stator etc.
Thanks  Ken

Answer
Ken, always start with a fully-charged load-tested battery.

Check all your ground connections and the electrical connections.

If your rectifier tests correctly. Try disconnecting your current regulator to see if your output increases appropriately.

Basically, the charging system is a capable of maintaining a fully-charged battery, assuming all the bulbs are correct specification. It isn't a "charging system", however.

Bill Silver