Lights dim when revs drop to idle

My SV650s K1 (Yellow toy town ) lights dim when revving then letting go to idle. Why is this, is it alternator or rectifier? Hopefully the latter.

[Viney]

By how much? Its a normal thing for them to dim a little as the output form the alternator/Dyno drops at idle. If its a huge ammount, then get checking the output form the regulator(Plenty of threads on here about it)
Welcome to the site by the way. Remember dont feed the animals and keeps your hands out of the cages at all times

Whats your idle speed as well that may contribute a bit more than usual if it is too low

Now you mention it my idle speed is a tad low, around 1100 rpm.

Check the charge you get from you reg/rec as Viney mentioned as its a sign that it could be on its way out, mines dying at the moment, just haven't pulled my finger out to replace it yet.
You know how you check the charge from the reg/rec?

Does your lights dim a little when your indicating, its easier to tell at night as your see the dash lights dim when your indicator flashes. If not then its probably not this... as mention it might just need your idle a little higher.

[Dave20046]

it's coz it's yellow, I noticed that on mine shortly before the regrec gave up. How is it when the brakelight is on?
Mine still dims slightly when the brake light is applied but nowhere near as bad as with the dead reg/rec

Originally Posted by forklift

Now you mention it my idle speed is a tad low, around 1100 rpm.

Knock it up a bit to 1500 rpm or just under, you should notice they wont dip as much

Idle speed should be around 1250 i believe. Mine idles at around 1100 as well. Lights dim when indicating but battery is good and charges well. Lights dim when brakelight is on as well however this is only at idle.

lights always dim a little when brake is applied at idle they dont do it on the move tho. idle should be 1250

1200 - 1500 is recommended but with the idle knocked up a bit it should help