lambretta - Vespa oil ratio

FAQ tech questions, please check if the answer to your question is in here before posting elsewhere.
mick1
registered user
Posts: 1292
Joined: Sun Dec 04, 2011 7:43 pm
Main scooter: Li Avanti 225
Location: York
Contact:

can anyone explain why a Lambretta is designed to run at 4% when a Vespa is running 2% ? This seems to affect kits as well with the Lambretta still needing more oil in the mix.

I'd have thought the pistons and barrels are the same material so so why the difference ?
User avatar
Bofs
registered user
Posts: 391
Joined: Wed Jan 07, 2009 7:25 pm
Main scooter: Zundapp Betta 500
Location: Derry
Contact:

It`s to do with the way the fuel/oil mix is fed into the engine.
Vespa`s are crank induction so the mix lubricates the crank big end on the way in and then the barrel piston area.
Lambretta`s are piston induction so the mix needs more oil to ensure the big end gets enough.
Muffspeed....no muff too tuff
Bad Samaritans SC

1957 Zundapp Betta 500 Auto
1966 Motovespa Sprint 210 Polossi
1960 Lambretta Cutdown 205 Project
mick1
registered user
Posts: 1292
Joined: Sun Dec 04, 2011 7:43 pm
Main scooter: Li Avanti 225
Location: York
Contact:

Bofs wrote:It`s to do with the way the fuel/oil mix is fed into the engine.
Vespa`s are crank induction so the mix lubricates the crank big end on the way in and then the barrel piston area.
Lambretta`s are piston induction so the mix needs more oil to ensure the big end gets enough.

A fair explanation.....so why do some of the lambretta lads lower the percentage on kits ? surely the same amount of oil is needed to lubricate the big end ?

Thanks for the reply
User avatar
Diablo
Dealer
Posts: 614
Joined: Wed Jan 07, 2009 12:24 pm
Location: Nuneaton
Contact:

Because modern cranks have better designed conrods to aid lubrication and also better big end bearings. Also oil technology has moved on loads since the 60's
Post Reply Previous topicNext topic
  • Information
  • Who is online

    Users browsing this forum: No registered users and 8 guests