Modern Vespa

I've noticed that my headlight and even the dashboard light dim when I brake. Is this normal?

Is it a lot? On my motorcycle the dash lights dim very slightly in time with the turn signal lights. Maybe your brake lights are doing the same thing?

How old is your battery? When did you last charge it?

Your battery must be low on power. Do you ride it long enough and often enough to fully charge it? Do you have power hungry accessories added to your scooter that might be draining your battery somewhat?

See - I wonder about this. I put a battery meter on my VTX and noticed that the 12 volt system is really a 10 (idle) to 14 (WOT) system. I asked around and was told most motorcycles are like this - few to none give a steady 12 volts and some are better then others. One of my Harley friend's bikes goes 8-16 volts! Anyhoo, this is why my dash on my bike dims a little when I'm stopped with the signals on.

Perhaps Vespas are similar? Now I feel I need to find somewhere to hide a battery meter on my scoot. . .

A bit of dimming is normal. As others have asked, does it dim a LOT? Our vespa electrical systems do work under the same principles as those of other motorcycles. This is one reason why we are not supposed to leave our high beams on for protracted idle... it draws down on the battery when the engine is not generating at "full steam"

This effect is more drastic in 2-strokes, where the engine is inherently less smooth running, particularly at idle. But, without having owned one myself mind you, the same should be true to a lesser degree on the 4-stroke engines. The electicity is generated mechanically, and our engines are running much much slower at idle, so adding lights, such as pulling on the brake, will increase the draw on the system... A strong battery should combat this to a degree, and this reminds me that mine is getting weak

I hope that helps.

Thanks for the replies.

The battery is only three or four months old. And I ride daily, probably 10-15 miles a day on average (including weekends).

It doesn't really bother me that it does this... It's not a dramatic dimming... I just want to know if it's normal or something I should have a shop look at. I don't ride at night a lot, so I just noticed it recently.

My Fly did the same thing. I corrected it by turning up the idle. The way the dealer had is set was too low and I would notice a big drop in my hedlight brightness when I came to a stop.

Put your scooter up on its centerstand and see if your wheel spins with the engine idling. If it does, you might want to back off that idle a little, bcs you're shortening the longevity of your belt. (check, also, that your rear wheel spins freely if you rotate it with your hand...there should be no friction from the brake). It's ok for your headlight to dim at idle. bikes aren't supposed to be charging your battery at idle.

Is that everyone's consensus? I was under the understanding that your wheel should rotate SOME at idle on the stand... my manual indicates such...

Mine says "Start the engine and tighten or loosen the idle adjusting screw, (B), until reaching the recommended idle speed, with the rear wheel not spinning." Idle Speed ~ 1600-1800g/min.

Elsewhere, it also advises you to avoid prolonged clutch slipping conditions to prevent overheating of the clutch.

What they do recommend is that the wheel is *able to turn freely*, with the brake lever released. Of course, that is different than saying that the wheel should be turning by impulse of the motor.

hm, thanks! My idle might be too high Hope that doesn't mean I've got a performance drop coming my way...

Do you happen to know if a low battery will cause the lights to go out when you apply either the foot or hand brake? Have a buddy that says I need to replace the battery, which is 3 years old anyways and should be done, but just doesn't seem like the cause.

I've seen other post of people saying they've ditched their battery's for KS, seems like if that's possible then a low battery wouldn't attribute to the lights going out?

BTW, I'm driving a 2005 PX150

Any advice would be appreciated!