Modern Vespa

Is there a way to make the throttle response a bit more linear, more analog on a modern Primavera 150? The bike has a very touchy throttle response from on and off throttle. What I'm trying to say, when you are trying to ride at very low speed in particular, it is very heky jerky. I thought it was just me, not used to riding a modern CVT bike, not having a ton of miles under me, etc. But my riding buddy has also noticed it when he has ridden it.

Is this a "feature" of fuel injected Vespas in particular? I know fuel injected bikes are more herky jerky than carb bikes. My last motorcycle was a Yamaha SR400, a 399cc single, fuel injected. But it didn't have such an abrupt difference between off throttle and on throttle. If it a simple matter of how the Primavera's fuel injection is mapped? If it is, is there a way to change it, to make it mimic a carb bike more closely? I'd rather not violate the warranty, but this really annoys me, especially at lower speeds.

As it is, it is really difficult to barely get on the gas with this scooter without it lurching, even for much more experience riders.

Sounds like the point where the clutch is engaging/disengaging. But of practice to get the feel of that point

We had that problem on my wife's Primavera (Mia) and solved it by increasing the free play on the throttle. A small adjustment at the throttle body was all it took. I think there's about 3mm play now and low speed control now exists.

This does sound clutch related.

One workaround that motorbikers use to crawl in traffic is to apply a little bit of rear brake while on the throttle - but this is only for walking speeds.

How many miles on scooter? Last service done? May be glazing on clutch?

It has about 570 miles I think. I didn't think about the clutch being the issue, except to wish I had a manual clutch to feather sometimes. When going really slow (think motorcycle driving test type of driving), I try to drag the rear brake. In fact, it's the only way I can go walking/jogging speed smoothly.

I got stuck in traffic the other day (school was letting out and it was stop and go) and the problem was really evident. It was an issue when I went to get my M endorsement on my license too. My friend, who has been riding for a dozen years or more, rode my Primavera and he commented on it too.

My first thought was that the fuel injection was just giving it too much gas off of idle. But I suppose it could be that the clutch 'suddenly' grabs making it lurch.

Could it be that it is just a really small capacity bike? What I mean, is that it revs more quickly than a larger engine with more moving mass? Just thinking.

I will pay closer attention next time I take it out to see what the RPMs do. So I'm thinking that if they jump with the slightest bit of throttle movement, it's the fuel injection mapping. I'll try it on the center stand to eliminate the clutch as a possibility. And if it is smooth doing that, then I guess it is the clutch.

Does that sound like a good way to problem solve it? Anything else that I can try to narrow it down? I guess this is going on the list of things to ask the service guys to check!

What year is your Primavera?

My LX125ie is smooth accelerating from a standstill but trying to keep it at around 20mph in 20mph zones and it becomes lumpy and doesnt respond well to throttle, sort of hesitating. At speeds of 25 to 60 plus mph it will run well at constant speed. My GTS 300 on the other hand seems to be able to do 20mph well. My only other issue is both speedometers favour kph and only a night can I read the mph scale well!
So I just caress the throttle when at 20mph because a twitchy right hand will cause laggy hesitant response.

It is a 2023 Primavera 150 (155cc).

Visit to the dealer to fix if not hour's away being under warranty still.

My LX would do that in the rain, clutch shudder. A good high speed run would clear it out somewhat.

Yeah, it's in another town, a ways away, kind of a pain in the derrière to get to.