Scooter Surges and Lurches at 50 MPH / Wide Open Throttle

[AgilityOnAnRV]

For the first time recently I took my newly purchased 2008 Agility 125 on a street with a speed limit above 35 mph. The scooter quickly gets up to ~45 mph, but just as it hits 50 mph it begins to lurch / surge. This particularly happens at wide open throttle. Easing off of the throttle slightly stops the surging, but the scooter still doesn't seem to want to go over 50 mph. Downhill with the throttle just below wide open it'll reach 52 or 53, but that's about it. I weigh 175 lbs and it doesn't seem to make a difference if my wife (~120 lbs) and I are riding double. Scooter still quickly reaches ~45 mph and starts surging / lurching pretty much at 50 mph on the dot, which happens to be around where I'm at WOT.

Any ideas? I'd love to solve this so I can go at least 55 mph and keep up with traffic on my newly found large street.

Thanks!

[Cortez]

I'm no mechanic, so don't ask me how to fix it, but it sounds like a carburetor problem.
That, or a plugged/dirty air filter.

The bike is either not getting any fuel or air.

I'm just hoping it's not worn out roller weights which might cause the bike to overrev
and bounce off the rev limiter (not sure if there is one).

The stock A125 should hit over 65 indicated.

[AgilityOnAnRV]

I'm no mechanic, so don't ask me how to fix it, but it sounds like a carburetor problem.
That, or a plugged/dirty air filter.

The bike is either not getting any fuel or air.

I'm just hoping it's not worn out roller weights which might cause the bike to overrev
and bounce off the rev limiter (not sure if there is one).

The stock A125 should hit over 65 indicated.

I don't think that it's over-revving. The engine isn't really whining and it sounds like it should have some more RPMs in it. Do you know where I would find the air filter and how I would access it?

Thanks!

[Cortez]

It's behind this panel, easy to remove:

[AgilityOnAnRV]

I never thought that I'd say this, but I just checked out the air filter and it's unfortunately pretty clean. Any ideas re: carburetor?

[juice]

I would try some seafoam gas treatment first . Use 1 oz per gal of gas . If a couple of tanksfull of that dosn't clear it up you will probably have to remove and clean the carburator . Good luck .

[AgilityOnAnRV]

I would try some seafoam gas treatment first . Use 1 oz per gal of gas . If a couple of tanksfull of that dosn't clear it up you will probably have to remove and clean the carburator . Good luck .

Just ordered a can. It should arrive on Friday.

[AgilityOnAnRV]

Started the troubleshooting possibilities today:

1. Added 1 oz Sea Foam to 1 gal of fuel in tank
2. Swapped out the old fuel filter for a new one

I'll give it a couple of rounds of fuel-ups with Sea Foam added each time and if the problem persists will probably look next to fuel mixture possibilities. I didn't see any loose fittings or cracked hoses when I removed the seat and seat well.