Modern Vespa

My Vespa GTS 125 SS has been running fine since I got it new in 2011.
Suddenly this week I started accelerating and got a distinct lack of power.

Looking at other topics I'm getting an idea it might be something to do with the air filter. I'm certainly hearing a strange whistling noise from that area.

I've read some topics asking what those bubbles are for at the bottom of the air filter and I've realised mine don't have any oil in either. Is this a sign?

I also read that dropping the bike on the left side while the engine was running can cause problems. This happened to me over Halloween when I skidded on some pumpkin in the road! Wasn't hurt.

Is it a trip to a garage or a DIY job?

Id definitely give it a good once over before you take it into a shop. Whats the service history on the scoot? Put the scoot on the stand and rev it and see if a friend can listen/look for where EXACTLY the sounds coming from.

Youre good since the bubble is clear. The bubble in the bottom of the air filter is to show you you have excess oil in your airbox from either the carb spitting some up or you dropped it. Look on you tube or search on here how to access the air panel and clean up any oil thats sloshing around in there and how to clean your filter if you feel inclined to.

Secondly, lift the bucket out from under your seat and look at the top of the engine for any loose hoses or fittings. If youd rather not probe around, take pictures with your phone and post them here for folks to inspect.

Give us some info so we can help and welcome to MV

Thanks for your comments and the welcome to MV!

I had a look under the helmet bucket and couldn't see any loose hoses so I think I'll have a go at removing the air filter this weekend. I've found some videos on Youtube although I have some rear crash bars that might hinder removing that bottom side panel.

Regarding the service history, it's been a bit sporadic because I don't do a lot of mileage but still generally once a year - although my local vespa dealer shut down a couple of years ago so I've been using a general bike shop since.

Interested in the conclusion of this.

Check your ignition, was half my issue still trying to figure out the rest. I'm half way through a valve lash adjustment to see of it helps!

Does your scoot still reach its top speedish?

The speed does seem to gradually build although on my commute I don't get a chance to reach top wack.

What's the mileage? Does it smell really gassy? And finally, when you do get past 50mph (if you do) does it pick back up/revs get higher all of a sudden?

Mine seems to be running really rich untill the higher rpms and I'm puzzled.

But mines a strange case...

There's other things it may be like the air filter and if your variator assembly hasn't been serviced that may well be the cause too.

Do the basics first, new spark plug, clean air filter.
I also saw that you said you don't do a lot of mileage, does your bike sit for a month or so with fuel in it at times? If so it may be a fueling issue.

If you get like me and you take it to a shop and still stumped, start working through things like valves ect

Thanks for your advice mate. I'll try the basics this weekend.

I ride it every weekday to work and back so it doesn't sit around for long periods.

Haven't noticed a gas (petrol?) smell.

The strange whistling noise may point to a vacuum leak between the carb and the intake manifold. Check the rubber for integrity.

I'll check the carb then, thanks.

JIM probably has the right answer but when was the last time you changed the belt and rollers? How many miles on them? They can make weird noises when going bad. BTW on your hoses. You can't see the cracks. Mine looked ok but when we changed them, this is what they did in my hand. I've had to do it every 4yrs. Second time it left me stranded. I smelled gas the second time. Good luck

Wow Judy. No idea what belt and rollers are but four years is about right.
I'll check the basics first and then take to a mechanic I think.
Thanks for your help, I'll take a look at the hoses.

Hey JimC. You don't happen to have a picture of the carb and manifold connection so I know what I'm looking for?

All in the workshop manual...

On Sunday I cleaned the air filter in soapy water, let it dry then applied some air filter oil. It was the only one I could get and was branded Filtrex.

There has been an improvement in performance but not perfect. The whistling sound stopped for a while but is now back and is accompanied by a sound like someone clearing their throat.

Does this mean I'm in the right area (as the performance has improved) but maybe didn't use the right filter oil?

I believe that is the same engine as my Beverly 125ie, it is fuel injected, no carb.

is your problem just when you first start out, like you have to baby the throttle, but once the engine is warmed up it runs well?