Headlight goes completely dim w/ start button.

[750k8kev]

Is it normal for my headlight to go very dim for the duration that I hold my start button? I am trying to diagnose a charging problem and just want to see if that's normal. I'd imagine it would go dim a little, but mine goes off. My bike hasn't been starting unless it's fully charged, even kickstart. I drove it around yesterday for about 45min, first 45 minutes on a bike on the road ever!!! woot! When I got back I let it sit for about 20min, it shut off and wouldn't start . I just ordered a used rectifier and regulator, hope that solves my issue. My rectifier harness is fried.

 

[BArTY]

have you tested your battery? might need a new one

 

[HerrDeacon]

Yes, its normal for the headlight to go off when using the electric start, its supposed to do that to free up all the power for the starter.

 

[750k8kev]

Thanks Herr. Battery is new. I'm pretty sure my rectifier is bad, especially because it's chard. This thread pretty much covers my problem. http://forums.sohc4.net/index.php?topic=70049.0

 

[hillsy]

Only way to make sure it's not charging is to put a voltmeter across the battery terminals when it's running to see if there is a voltage increase.

FYI - static fully charged battery should read 12.8v, battery in running bike at 4-5K rpm should read 13.5 - 14.5v.

 

[Rocan]

could also be a loose connection or faulty starter relay. check those.

 

[crazypj]

Yes, its normal for the headlight to go off when using the electric start, its supposed to do that to free up all the power for the starter.

That only happens on modern bikes.
Kawasaki started it at least 10 yrs ago, Suzuki only about 3 yrs ago.
It's more likely battery is low and starter motor has worn brushes or seized bearings.
Checking voltage is a good first step but really you should do an amp draw, anything over 90 amps when you hit the button means a big problem

 

[Feed_Sparky]

That only happens on modern bikes.
Kawasaki started it at least 10 yrs ago, Suzuki only about 3 yrs ago.
It's more likely battery is low and starter motor has worn brushes or seized bearings.
Checking voltage is a good first step but really you should do an amp draw, anything over 90 amps when you hit the button means a big problem

Both my CL and CB 360 headlights go out when the starter button is pressed, well the CB used to when it had a starter... There is a rocker type switch behind the starter button that kills power to the headlight when the button is pressed.

 

[verboten1]

That only happens on modern bikes.

if by modern you mean my '82 yamaha....lol