Headlight gets brighter when I rev...

[Guest]

Hi all,

Quick question, I have a 1981 GS450 and my headlight gets brighter when I rev the throttle. Is this bad? Should I worry about this? Should my R/R be ensuring that this doesn't happen? The bike seems to be running fine and the battery is not losing a charge from what I see (found a short that I previously posted about and fixed that).

Thank you!

[hillsy]

That sounds normal. You should probably get a voltmeter and check the charging at the battery at various revs - 13v at idle and up to 14.5 at 5k rpm is normal.

[Brendan W]

As hillsy says it's normal for the light to brighten as revs are brought up from idle. It's part of my starting off checks. It should brighten and then cut off. If it's still brightening appreciably over 3000 rpm I would suspect the voltage is going too high because the regulator is not limiting it properly.

[Steve]

Yep, a voltmeter is a rather important tool to have. IDEALLY, it would be nice to have a full 14+ volts at all times, but the way these systems work, it is inevitable that charging ability is less at idle. It is somewhat common for voltage at idle to be less than 13, but it should rise dramatically when the engine speed is raised above 1500 RPM, and should be over 14 by the time you get to 2500-3000 RPM. Although Suzuki feels that 15+ volts is OK, that tends to wreak havoc with a wet-cell lead-acid battery, so keeping it under 14.5 volts is much better.

.

[benjo]

So, I actually just realized it’s the other way around. My lights dim when I rev the throttle. Any insight?

[posplayr]

So, I actually just realized it’s the other way around. My lights dim when I rev the throttle. Any insight?

Here is some onsite: do the Quick Test.

[hannibal]

If the light gets dimmer when you rev, I'd suspect the you're not getting more voltage. The battery quick test link in posplayr's signature will test for this.

[benjo]

Gents,

After much technical and scientific testing and analysis, I found that.....a grounding wire was loose!

Thanks for all the insight though!
Benjo

[Brendan W]

The phrase, ' He has a good grounding in bike maintenance', comes precisely from this.