Modern Vespa

I have a PX200 with the following mods.

* Ports cleaned up and polished
* 1mm shim under barrel and 1mm shaved off the head
* Electronic ignition reset to match shim
* Simonini exhaust
* Air cleaner drilled out with a 'heart' shape hole.

With the air filter mod I had to get to a 138 main jet before it stopped running lean.

However when I run it with the original air filter I only need a 125 main jet before it runs right.

So for all those doing this air cleaner mod beware because it leans out the engine quite a bit and you must up jet.


Air filter NOT DRILLED (stock)

Air filter DRILLED (modified)

I noticed something similar on my 150 a while back and decided against leaving it that way. Fortunately, I ordered a pre-drilled filter just to try this and kept my undrilled original.

What it does has long puzzled me too, it's like an air corrector in front of the two air correctors, and a sloppy one at that, given how poorly many filters seem to fit the top of the carb.

Last edited by pdxjim on Thu Jul 02, 2015 9:39 am; edited 1 time in total

Surprised you need to go up thirteen sizes just from drilling the filter... seems like an unusually large increase given the relatively tiny amount of 'extra' air that enters thru that unsealed opening. Something else might be in play, but I'm sure your mechanic has it sorted.

So which set up are you going with ... drilled or undrilled?

I'm using a stock filter which is not drilled. The mechanic also said I could probably go down to a 122 jet and still be OK but because I wanted to play it 'safe' he suggested just leave in the 125.

Over the past sixteen years I've done about (guessing) 45000 kms on px scooters four of them. .All with drilled filters and never had to go above a 122 jet with stock or sito plus exhaust stock 200 barrels on three of them and apolini 177 on the other.


so im not convinced

Yeah I'm with you Josh. This whole air/fuel thingy with 2 strokes is all black magic to me. I'm sure there's a proper science behind it but I don't think I'll live long enough to learn it all.

Sad part is I bought a $60 dremel to make the hole and ended up with a heart without love.

What temps are you getting from the CHT before and after the changes? You aren't doing exhaust or filter mods without first bench-marking the stock readings I hope.

SIP are selling this as a stock Piaggio filter for a 24/24.



http://www.sip-scootershop.com/en/products/air+filter+piaggio+_40250000

I'm thinking about one of these. Comes in 24/24 and 20/20

http://www.sip-scootershop.com/en/products/air+intake+system+polini+ve_20301520

I don't think I've ever done what you're asking. Mainly because I have no idea what you're saying.

All I know is that after the real experts finished with it it now runs great and safe.

It's now time to leave the darn thing alone and just enjoy riding it.

yeh im still sceptical manit,, your basicly saying some dude who worked on my engine told me such and such and now im telling everyone else because its my engine


who was it that told you that/ fixed darrens /marks work

dazza and mark know what theyre doing so who fixed it again man?

Werent the 'extra' holes standard in Europe? Only blocked in the usa? Think I read somewhere Oz as well but i am not sure. The filter on my rally has the holes already and that can from the UK albeit with a p200 engine. Just wondering aloud really.

yes your right mate, my first px which i bought as a teenager and rode home with no licence had the holes already and i did several thousand kms on it too,,,,
perth to bunbury twice and perth to pemberton once then perth to margaret river once then perth to nannup several times......

..no problems with the jetting it was only logging trucks and psycotic farm hands in utes i had to worry about. pre internet days really but i did know how to de-coke and look at plug colour,,,,,,,,the only problem i had was it being a fucking shopping trolley

oh yeh, that px200 that i did all those trips in had a 118



the px i have now has a dremmeled out heart and is still 116 which i think could be risky to be honest but my commute is less than 2kms each way so waiting on more jets and a few parts



how does the drill bit measurement go say i want to turn my 116 into a 120 what size drill bit is that? xx

A significant majority of the "maintenance" on a shifty Vespa is pure and simple voluntary tinkering. A significant portion of the remaining "maintenance" is as a direct result of that voluntary tinkering.

Yup, Monit, ride it.

I've yet to hear anyone on any forum offer an authoritative and convincing answer to the following...

1) Were the holes specifically for certain regulatory markets, such as the U.S, and unrelated to engine size?
or
2) Were the holes specifically for certain engine sizes and coincidently related to specific markets?
or
3) Were the holes specifically for certain model bikes, such as the Cosa and later adopted for other models?
and
4) How far back does that heart shaped cavity go on Vespa air filters?

Last edited by pdxjim on Fri Jul 03, 2015 7:13 pm; edited 2 times in total

No one 'fixed' it again. I sent just the basic engine to Mark. Once he did all the work he sent it back with a 122 jet. It ran crap and Mark would not have known the carby was bent. This was my fault because I replaced the carby base gasket prior to sending the engine to Mark and didn't realise there was a proper way to tighten it.

Then as a precaution I gave it to a reputable scooter shop (Scooter Style in Noosa) to tune the new carby. All they discovered was with the filter drilled out (even beyond just two holes) it was taking a 140 jet just to get a plug that wasn't white.
The undrilled filter ran a nice plug at 125 and would probably also run safe with a 122.

I did the filter mod about 12 months before Mark did all this engine work and it ran a very nice plug with lots of 100kph journeys.

They're the facts.

This is my opinion: It just appears that the combination of the work done AND this filter mod is not a good combination.

They are infractions of a mm, so you'd need a 1.2mm drill bit.

I jet my 150 like this. I've got lots of jets that are too small to be useful to me, so I take a 1mm drill but and ream them out till it's just right. With the simo pipe I'm guessing it's between 105 and 110. I'm a cheap bastard.

josh you can buy a set of micro drills for this purpose, for example...

http://www.ebay.com/itm/20-Titanium-coated-mini-Micro-HSS-drill-bit-set-0-3-1-6MM-in-dispencer-Case-/361296095255?pt=LH_DefaultDomain_3&hash=item541eece817

not exactly a reamed hole but they work

I noticed that after replacing my original filter and jets that the filter would not even fit with out the drilling holes. I think the heart mod is just the result of manufacturing differences that just so hapoen to let it breathe better.

I've drilled jets before. If you really want to know exactly what size you have drilled, get a tapered needle like the one below. It's for some kind of knitting or something, I can't remember just now.
Anyway you draw black on it with a texta/sharpie/permanent marker, then put it into the jet and twirl it a bit. Pull it out and you'll see a ring where the hole has rubbed the black off. Get your verniers and measure the diameter at that point.

This is some serious science man. I can't imagine the gap between what you know and what I will never know.

Love stirring you up

Couldn't find a 1-2mm drill bit at the hardware shop. Oh well I've got burl bowls to carve instead.


Box of jets hopefully won't be too far off. I got a trailtech Guage on its way so I will see how hot it runs with no heart and a 116 (for science )

Hahahaha. Ya bugger!

I have a problem with my P200 engine at the mo. With the air filter (non drilled) on, it struggles to start,but with the filter taken off, it starts within 2 kicks! I did have trouble with a stuck float ( fuel pissing out of the exhaust!) but that's been sorted. Could this be related??

Cheers

Graham

it's a modified crochet hook, you could make a hat first and then check your jet size

Hence the haberdashery department at the Dellorto factory... it's all beginning to fall into place now...