Modern Vespa

Hey guys thanks for stopping by, I'm planning to move to Edinburgh and I love vespa's stopping by the factories of lambretta and vespa getting to know we'll known collectors.

Anyway I am looking at 1976 maroon red vespa 90 all original (2000km) and need to push top speed from 45mph up to at least 55mph cruise on flat roads. Yes I understand there are many 130/135cc kits however I'd have to pay over £800 to get the correct licence for only 5cc more, is it possible to fit a 125 primavera (non et3) with the same stroke into this engine? What kind of modifications to the case have to be done to make it compatible? (exept for smoothing out, easy proccess)

Other modifications I'm planning to make: 19.19 sbhc dellorto, surflex 4 plate reinforced clutch, replacing crank bearings( depends on condition of others too)/all seals, 24-61 primary drive (what's suitable for light person for versitile acceleration and speed?)

This is simplified but I've seen 20 hours of people working on smallframes but never been able to find someone on this forum and Internet attempting it do this conversion.

Thank you and sorry if I don't have specifics correct.

I did exactly this conversion w/ no problem on my favorite smallie in Greece. Stock but port matched 125cc Primavera top end on stock 90cc case & crank w/ a bigger carb and better pipe but stock clutch and I retained the stock 90cc primary gears which are midway between the stock 50cc 'granny' gears and the higher speed 125cc gears. I do some offroad riding and like the gear power the 90cc gears offer, but I'm not sure I can hit 55MPH. Look here: https://modernvespa.com/forum/topic123613.14#2323450



Setup for offroad - no muff or centerstand dangling and a 16 ga bashplate w/ reinforced edges plus that gearing.

Appreciate reaceate your reply, port matching in this case only involves taking material away or is it adding and removing? Also what 125cc kit would you recommend, one such as this :
:
https://www.sip-scootershop.com/en/product/racing-cylinder-pinasco-125-cc-25030790-for-vespa-50-125-pv-et3-pk-s-xl-2_79400000

Or original replacement, fitting one for stock primavera 125

Nah, nothing major and I only removed material. It's the SECOND motor that's painted black I posted in this thread.Cannot recommend... The first engine is now much the same but started as a 50cc so also needed to change crank and primary gears.

Also here https://modernvespa.com/forum/post1904591#1904591.

Sorry, I'm the wrong guy to ask about best smallie kit, I've been lucky twice getting free stock Primavera top ends for these two motors when friends upgraded to better kits.