I have an 84 V35ll that has developed a charging problem.
When I first start it everything appears to be ok with the ign light going out about 2k revs but as I travel and the bike warms up the ign light will come on as I use more throttle and increase the revs up to 5k but as soon as I snap the throttle shut the ign light will go off, a slight opening of the throttle and the light still stays off but any heavier increase in the throttle results in the light coming back on .
Anyone got a clue as to possible causes.
I don’t think the charging system is keeping up with the needs of the HT circuit and you’re getting the friendly warning prior to failure. Check your rectifier output for confirmation.
Wait for more suggestions before spending any money, I am not the board expert, just bored 
Phil
Test the how well the alternator is doing first before pulling the electrics apart and buying new bits.
If the output of the alternator is low check for worn brushes and dirty slip ring.Â
I am no genius with the mysteries of the electrics but I removed the alternator and found one of the brushes seemed to be sticking in the holder so I removed it and soldered a new one in started it up and woohoo the light goes out as soon as it starts to rev so fingers crossed .
Congratulations, always look for simple solutions before pulling stuff apart! The brushes do wear and if you have replaced them it is also a good idea to clean the slip ring as all the worn brushes end up as dust all over the place in the alternator.
Have fun with the bike!Â
Beat me to it Chris, classic worn brushes symptoms.