Sorry for not perfect english- I still learning;-)
Im Balki from capital of Croatia/EU- Zagreb. Two years ago I bought my 1st "bigger" scooter Sportcity 250ie with 24kkm after my few 50/70ccm "rockets". In same time I started to follow Modernvespa and get idea for some "upgrades".
I made bigger valves in original head and piston machining, tuned airbox, rised fuel pressure to 3.5 Bar, put Polini Hi Speed... but nothing happens. ECU simply doesn't alow any significant performance improvement.
Then idea was born about engine swap and research started...
Since Beverly 350ie share the same 250/300ie engine without any chasis or body adaptation I found that "project" can start. I found used 350ie engine with wheel and support arm. Wheel still had original tire what means that runs about 10~max15 kkm;-)
On ebay I found starter, airbox, manfold, exhaust, lambda, harness... and ECU without keys.
Guy from local forum mojskuter.com programmed me key transponder like "master key" and gave me needed antenna.
Original SC harness have 26 pins connector so I cut 350ie harness, found 26 pin male connector from faulty Bev500 ECU and made interconnection cable 26->34 pin.
From 350ie injector i removed original "rail" pipe (wo flow) and put rail pipe from original 250ie injector with flow- on this way I didnt had to make fuel pump modification.
With antenny and precisely placed transponder new ECU "recognized" key what I seen by added blue LED with 2kOhm resistor...
I successfully put original SC engine supporter to engine with small effort but found that whole engine and wheel stays 17mm "offset" on side. Small cut and weldings + few washers solved this problem and now all stays perfectly alligned. I must say that previously I "filled" support silent blocks with "SIKA Tack Drive" car glass seal and they are now much more stiff. Bottom end of shock absorbers also asked for modification but side cutter and welding machine was my friend again;-)
Finally I get what I want- fun, quick and agile scooter for city and local roads what not shame from longer seaside trips;-)
After few weeks of testing I found that gear was filled with gear oil but I replaced it with Eni i-ride 15-50 based on manufacturer SVC bulletin since they found that "wet clutch" doesn't like high density gear oils.
Here are some photos what can help if someone want to make the same on his Vespa or other scooter with Quasar engine;-)

Last edited by balki on Thu, 05 Sep 2019 21:11:56 +0000; edited 3 times