Engine hesitates (back and forth) at higher speed???

[Scootermama]

I have a 2009 People 150.  When I first purchased used, I could get it up to 65mph.  It sat for over a year and took up to mechanic to get carbs cleaned, new spark plug, etc.  Got it back with jerky jolts when applying throttle from a stop position that went away after getting up to 5mph.  Also, when getting up to 40 mph, power just drops off in a repeated hesitation motion (back and forth).  Dealer and a different mechanic stated needing a new belt and rollers.  Had that done.  The jerking at first applying the throttle has stopped, but not the hesitating at high speed.  Dealer states they don't know what it is without tearing it apart.  Well that sounds like more than I paid for it.

Any clues?

[Iahawk]

hesitation at low and high speeds could be a sign of a carb that is still dirty. How many miles are on the scoot? If it ran well before storage...and then ran poorly when taken back out of storage I would be less likely to think it is belt and rollers and more likely to think dirty carb.

[Scootermama]

There is 12,000 miles on the scooter.

I took it back to mechanic and he did a thorough re-check on the carburetor and spark plug.  I also had the belt and rollers replaced that did stopped the jerky take offs.  He never drove it before at higher speed - and drove it this time stating, "It feels like it just cuts of power for a second and then comes back.  You can replicate what it is doing at a lower speed by hitting the kill switch quickly, then back on."  So his suggestion is electrical and wants to replace the ignitor box.

Earlier he stated thinking it was a limiter (Can't remember if that is the word he used, but like a governor that keeps it from going over a certain speed).  Called Kymco, they stated The People 150 doesn't have one.  Mechanic stated never seeing a scooter without one.

So, he suggested looking at some scooter race sites to get an ignitor box that allows a higher speed.

Any thoughts anyone?

[CROSSBOLT]

Sounds like your "mechanics" are taking you for a ride...

[Kansas kymco]

 You still have a dirty carburetor and only 50cc scooters are restricted to meet speed limitation laws for licenceing.  Happened to another poster on the forum that the mechanic said he cleaned the carburetor.  When taken apart was still dirty.

Another thing that will help is use only non-ethanol gasoline, especially if the scooter sits for extended periods.  You can add one  ounce of Seafoam gas treatment to a tank of gas as a fuel stabilizer and cleaner that might help as well.

I bought a People 150 that had sat for several years and the carburetor was so bad it couldn't be cleaned and I  replaced with new carburetor.

When ethanol-gasoline sits for extended periods it attracts moisture.

Your mechanic is incompetent.