Honda-SOHC

Hi All.  I know this bike is not a four but I am sure some of the expert club.members will come up with a solution.
The problem is the headlamp bulb blows once the engine is revved over about 4000 rpm, according to the Haynes manual all the other electrics are rectified and regulated but the headlamp is not,it runs off AC through a yellow cable from alternator to lighting switch through a resistor that should be mounted on the forks but is missing. I have converted the bike from 6volts to 12volts and everything works fine 13.5 /14volts at the battery flashers work fine even with side and brake lights on. I don't fancy reverting to the crude lash up with a resistor in the wiring. My  solution would be to replace the original 4 cable silicon rectifier with a 5 cable rectifier/regulator from (China £6-00 inc p&p)then connecting alternator yellow cable to the new rectifier/regulator.
Would this be OK?

Thanks in anticipation
Frank Webb

Hi Everyone is it possible to get replacement clutch drum rubbers?  I have a spare clutch drum that had extreme movement in it so I drilled out the rivets that hold the plate that retains the rubbers in place, the rubbers have broken up.  I have been told that one has to buy a complete clutch drum as the rubbers are not available separately.

Has anyone reriveted a clutch basket on a 400/4, mine has a lot of backlash but is otherwise in good condition.  I don't want have to buy a new one.

I bought my 1976 400/4 about seven years ago as a scruffy Dunstall Cafe Racer non runner.  Recently I decided to get it running the  fault was with the wiring on the Lucas electronic ignition. I changed the oil and filter fitted a new battery and took it for fifteen mile run. The clutch is fine as is the gear selection the only thing that disappoints me is that in all gears there is a loud whine when the engine is under load or just cruising along. As soon as the throttle is closed and the bike is on the over run the whine completely disappears.
Any advice please I know I will have to strip the transmission to rectify the fault.  What parts are most likely to be worn?

Thanks
Josse