Hi can someone confirm the smaller inlet port /transfer?

[george1966]

If you compare the hole from the carb to the crankcases on yours and an early P range, this hole, the inlet, is smaller on yours so it's not going to flow so much fuel.
Inlet timing is determined by the crank web and the length and positioning of the inlet hole. Between them they control the duration of the the inlet of fuel into the crank case. Or if you like, the inlet timing.

It wouldnt suprise me if the transfers are smaller too, i dont really know tbh.

Changing the inlet timing would involve a full strip down and rebuild

Please remember i have no experience with theese cat'd motors. This is what i read from various forums.

Read more: vespa.proboards.com/thread/5257/px-125-euro-restriction-restricted#ixzz3qTPGkmbe


hi i have a chap that tunes and builds engines i need to find out all the ......cat restrictions,the exhaust ,carb slide,secondary air,cdi

i have all the info on them .............but i cant get any info on the inlet and transfer ports?

thanks
george

 

[henri]

transfers are similar ,an easy to enlarge/match to barrel. the inlet is smaller giving a later opening n earlier closing ,havent any figures as guys only ever post there finished specs not often there starting place . H

[sime66]

I don't know if this helps, or what relevance it has to a newer, restricted engine, but I did measure mine before opening them up – a 1982 standard px(150) casings and standard Piaggio (also 150, but off different engine) crank. - I don't believe the 150 makes any difference, but the age/restrictions might. You have to measure the cut-out on the crank, and where it is relative to TDC; and the opening on the inlet pad on the casings, where it is relative to TDC. I did a drawing ('cos my brain sees stuff better with a jotting):



This shows my original inlet timing to be 109/43. How much you open it up isn't a simple choice; for my needs I went to 125/55 for mine, like this (opening casings and cutting crank):



Hope that helps, but that's only what I found and what I did, just to give you an idea.

---

Likewise, you need to first measure your transfers, then decide what mods you need to do to get you transfers (timing/size/matching) right for what you want from your scooter - all of mine are here:

vespa.proboards.com/thread/4621/comparing-px-efl-gearboxes

[george1966]

Hi guys thanks for the info ,I have a friend thats suggested we build a 125cc engine to either 1982-1997 (8.6 BHP)standard specs or 1998-2008 (9 BHP)standard

en.wikipedia.org/wiki/Vespa_PX

I,m trying to find out if the inlet/transfer ports are different/smaller/larger on the crankcases on the 1982-1997....1998-2008 euro 2...2011-2015 euro 3 px,s ,he had what he describes as a bullet proof very smooth running quick and quiet 125e pre cat/euro
but we just cant get any info on any changes made to the crankcases over the years?i have contacted several companies that sell engines,crankcases etc but no response? is it a national secret lol


george

[george1966]

You are a star many thanks
george