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I don't know about this specific engine, but I have tuned a lot of 4 stroke 50s over the last 5 years.  Once you get the CDI sorted you should look to your CVT system.

Get a performance variator and replace your rollers with Dr. Pulley sliders.  I'd go a couple of grams lighter than stock.  Next swap your 3 small clutch springs and the big contra spring.  Go up one step.   Most 50's come stock with a 750 rpm spring.  Switch up to a 1,000 rpm spring.   I normally replace the stock belt with a Gates Powerlink belt when doing the clutch springs.   I don't know what the upgrade in belt would be for your scooter.  Thought I'd throw in my two cents.  :-).

You will end up with much better acceleration and a bit more top speed.

Thanks a lot Abner_Bjorn!

I have a couple more questions about your way of modifiying the scooter.
What weight should I choose the sliders to be exactly? Does 5.5g sound like a good choice?
And do I have to replace the clutch springs and contra spring with +1000 rpm ones? I'm not sure what the + means.
I don't have to the tools and experience to do that myself, so I thought about buying the parts myself and bring it to my scooter dealer and they can do the replacing for like $10.

Furthermore do you think it's a better idea to make all these CVT modifications instead of replacing 50cc with a 80cc cylinder?
How about the wearing of the motor, will it last shorter than with stock parts?

Redguard

Hello guys,

For 3 weeks now I'm a proud owner of a 2nd hand Kymco People S 50 scooter. I like it a lot except the engine power that could be better. So I brought it to my dealer and told them to boost up the perfomance. I discussed possible modifications combined with my prior research and we agree that they will install an unrestricted CDI and exchange the variator rollers. They tried everything but said in the end that it didn't make any difference so they put the original parts back in. They told me it's just the engine and the scooters weight which doesn't allow more performance.

I'm sure there must be a way to get more power out of that engine. They said the only way now is to replace 50cc with 80cc. Is it recommended or should I keep trying other ways? I'm not sure with what kind of "unrestricted" CDI they replaced the original CDI, but shouldn't it make at least a small difference if you put a proper derestricted CDI in there? As I read most restrictions on these Kymco scooter are on the CDI. And are there any other ways to boost the engine power?
At the moment I'm reaching a top speed of about 35mph and the acceleration could be better.

I'm pretty new to all this so I'm sorry if I'm maybe using improper terminology.

Thanks a lot!
Redguard