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Blizzo's Vespa thread


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Well that was dumb. Seems we lost the days posts, including the first new thread I've Started in like 4 years. Oh well ill start again.

So went something like:

Ive never really been a Vespa foamer, they are European and 2 stroke, that's two things that have never gone that well for me and both combined. 

About a year ago a fellow penny pincher, Ghalal got given a PK100s that someone had stripped to "modify" but realized they weren't even capable of undoing wheel nuts so gave up. unfortunately they lost all of the bits they took off (quite a few bits) so it sat in a sad state until it was given to G for free. It then sat in a sad state at G's place, he tried to get it to spark but it wouldn't so he gave up on it. Over lockdown I did a bunch of work on a C100 that PPSC and friends put together to donate to G after his bike got stolen. Being the bloody nice bloke that he is, and in lieu of his work G donated the Vespa to me. I didn't think too much of it and just poked it in the corner. This is how it arrived.



Que QCR Dirtmasters being announced with a 125cc limit, my other small bike is a 140cc and there was emphasis on least practical bikes as possible so I thought building this thing would be perfect. I did a bit of interwebs searching and found that the Italians build these smallframes (mostly PKs as they are "undesirable to vespa barry's) into 17hp hotrods and launch them around full sized MX tracks. that's my inspo sported.




So I needed to get the thing to run. i stripped out all the wiring and hooked up the 2 wires that the CDI / engine needs to run and whammo she fired. well after considerable push starting and start ya bastard down the street it fired. it was a slow as a wet week and ran like a bad of shit, clutch was also super weird, more investigation needed.


Before I got to pulling the engine I wanted to weld the frame brace in so did that out of some 25mm tube. She's a full 3/4 race scoot now.


Pulled the engine and started stripping it down, jeeze these things get grubby


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found out why the clutch was dicky, aside from having almost no cork left the locating tabs had been based to shit by the basket, there was about 60ml of oil in the poor bloody thing.



While I was at it I "lightened" the flywheel by heating up the ring gear and bashing it off. no need for electric legs when you have 3 ample sized real ones.


Next up on list of “wow check out how fucked this is” was the bolts holding the rear wheel to the hub. They had obviously been left loose and the wheel had been chattering for quite some time. Photo below was one of the better ones. Someones lucky they didn’t die.


So I got talking to a bunch of Vespa dudes about how I can make this go “well enough for a bit of fun at dirtmasters” but I didn’t want to go dropping several hundred dollars on a Polini/Malossi cylinder kit. I was wanted to do some barry mods and bolt some second hand shit on to get it going well enough to be a bit of a laugh to ride. Spoke to a bloke named Matthew Brookes who’s now down in Milton and is well versed in these things. Less than 200 dolarydoos later I had a new seat (the single seat was shit) a PK125 3 port barrel and head, a new piston and rings, an alloy packer (will get to that later) and all the gaskets/seals and shit id need to rebuild. I thought about changing the primary gears too but the low 100 gears which top out around 80 would be better for around town / on the dirt.

First thing I did was strip the cases and port them to match the transfer ports on the cylinder. This was easy using the packer as a template.


The thing was pretty bloody grubby on the inside. I ended up completely stripping the cases and bead blasting them.


On the flywheel side of the engine these things use a weird 2-piece bearing that makes it easy to split the cases. Sadly, for me this thig was koozed, was all carboned up and super grumbly, so off it came.


Unsure if it’s an Indian PK125 copy or something but I havn’t seen one that either uses a copper headgasket or Oring like this does. Ill grab a viton Oring to use as a gasket anyway.



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so, like all things I do, I couldnt really do this vepsa thing in halves, and one wasn't going to be enough. 

I had been talking to one of the blokes in the Palmy SC about various smallframe vespa bits , has a cool hotted up SS90 replica. He mentioned a local old girl that was selling a 60s smallframe 90 that was "all there" but in a few bits and pretty straight. He said what she wanted for it which sounded pretty reasonable so I had a ponder on it. Was a sunday afternoon when @Sparkle was around at my place and he convinced me to go check it out, which we did. Unfortunately were son had pulled it apart and ruined the orignal paint by giving it a barry rattle can job but other than that it was surprisingly OG. I had just brought another smallframe but it was nothing like this so decided to flick on the ratty one and grab this. I struck a deal with the old girl "Trish" and that was that.

Went and picked it up a couple of days ago, its quite the honey and my wifes already in love with it.


So the story is, its a 1966 vespa 90. Some will say that no its a pre '65 Vespa 90 because its a "Small door" model, but ill get to that later.

The Scoot was sold brand new to A Judith Brown from Kaponga in 1966. Patricia (Trish) Martley purchased the scoot off Judith in 1967 when it was a year old. Trish had owned it every since. This is some of the kack that it came with, along with another big box of spare parts




The clever eye will notice the absence of a Piaggio frame number here, under the engine door where its usually located.


And this little tool/rego holder opens up another neat bit of history


Discovered this through the interwebs:

"Up until 1984 NZ had a heavily regulated, central government controlled economy, (on reflection) and in short it was a democratic, benevolently communist environment. As such import licencing was very strictly controlled to protect local manufactures and markets.

Airco, an Auckland based company held the NZ licence to import Piaggio/Douglas Vespa scooters in CKD (completely knocked down) form which they assembled and distributed. The licencing regulations required that a certain amount of local materials/manufacturing/labour/etc went into any imported product to further support/protect NZ businesses and markets. Airco made the seats locally which they badged after themselves and assembled the frames which were stamped with their manufacturing number code (sometimes not stamped at all) .They were then distributed and sold as Vespas to a waiting list of buyers...new, foreign made anything always sold at a huge premium (tariff loading) and had an air of exclusivity.

Models available over time were early wide-bodies, early Douglas Vespa 125 variants, GS160, SS50/90's, Douglas Sportique 150, Super 150, SS180 and Rally 200 and some other models from time to time along with the odd, VERY expensive, privately imported machine (and you needed a very large stash of foreign funds to get passed the authorities).

They were available in an almost Henry Ford rainbow of colour options...Roma Red, Peacock Blue and "appliance" White.

NZ never had a VIN system back then (pre golbalisation/Americanisation). Vehicles were registered at the Post Office by chassis/frame number and engine number. Registration had nothing to do with a certificate of ownership (no one ever had such a document), it merely documented vehicle information as cover for a Government tax. Airco stamped the frames with a manufacturing number (4 digits) on the frame which became by default the frame number. I had one SS with no frame number at all (probably a replaced frame at some stage) but the rego paper had a frame number recorded. It wasn't until the late 80's that NZ adopted the VIN system, registration papers became obsolete and everything became computerised to the global standard"

So yea pretty rad.

Not too sure what the plan is, I like the OG poverty pack look of the steel wheels etc. Will likely build a nice torquey polini 130 engine for it or something with a vintage looking faco pipe. dumb thing is the 90s are 3 speed so could either leave it that or convert to 4 speed. but yea, all original build but with a bit more boogie, bit of a sleeper etc. Its down on the project list so will have to wait. its a shame its had the respray, because of that I might have it blasted, properly panel beaten and resprayed in the original color. wouldn't use base/clear though, i hate stuff that's restored shinier than what they were new!

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The dirt PK100, now affectionately names "the chuddy" had gross indicator holes on the front legshield and and rear pods, as PK vespas do, so I decided to do a quick slap up job and fill them in.


and a quick one swipe bog smear and she's golden



then a bit of a buzz with the orbital sander followed by a quick hand sand and its good enough for a race bike



its quite convenient that VHT silver wheel paint is almost the exact same colour, so the entire bike got the treatment of one can, no way I was splashing out for two. 



Cut out an alloy blank plate for the left hand rear pod. this will get a race number painted on it eventually. whacked the seat on and its starting to look like a bike again.

I hate checker plate but couldnt think of an easier way to get some grip on the floorboards, so hacked some bits out with he jigsaw and riveted them on. Also ran some rubber trim around the legshield to save severing any limbs.


Filled the headlight in with a piece of alloy, thinking of painting something on it to get away from the blandness, jury is still out on that, was thinking a KC daylighters cover or something.


vespas are rotary valve inlet, opposed to reed. unlike most rotary valve bikes that use a separate disc with a hole in it to set the inlet opening / closing and duration vespas do it a bit of a whacky way. they use one web of the crank to control the inlet, so to modify the inlet timing you "cut the crank" or modify the rotary valve sealing pad that the crank web rotates against.

the photo below shows the "cutout" of the crank, the edge on the right closest to the big end bearing dictates the closing of the inlet ATDC, the edge on the left dictates when the inlet starts opening BTDC. the current timings of this crank, which as a PK100S already has the longest duration of any stock crank is closing at 55degrees ATDC and opening at 110 degrees BTDC.


The science behind inlet timings confuses me, ive read the jennings and G. Bell books but still failed to accurate formulate what my ideal timings would be. talking to Vespa barrys they reckoned leave the inlet closing at the 55 degrees that it is already at in order to not sacrifice mid range power, and have the inlet opening a little earlier. the Jennings book gives a general rule of thumb for "a broad range of power" of having the inlet open "at the same point the transfer ports in the cyl are closed". this results in zero overlap. more peaky engines can run up to and over 10 degrees of overlap. I have cut my crank to now have the inlet opening at around 122 degrees BTDC which is when the trans ports close on my modified stock cylinder.


the image below is the rotary sealing pad of which he crank web with the inlet cutout rotates against (with a very precise fit) to form a seal. You can see there is extra "meat" on the inlet closing ATDC section. Porting this out can have the inlet closing much later, peakier race engines will close around 70 degrees ATDC. im going to stick with the advise of the british vespa barry's however and leave this as is at this stage.


For reference the last two stroke bike I owned, a suzuki GP125, which go bloody well at around 14hp stock but are a little peaky have an inlet that opens 145 BTDC closes 55 ATDC.

O well, hopefully it works.

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  • 1 year later...

Hey @BLIZZO I saw your vespa for sale on trademe, for other reason I couldn't afford it and the ad was gone,  I tried to contact you but couldn't find any info on trademe and now I finally found it again, unreal!

Is the vespa sold?  I do have a 144 pinasco coming to NZ from back home (italian here) and that bike would have been an awesome start for a race bike, hoping to bring a vespa to a victory in a bucket race!

 I'm from Picton, still looking for one so if is still there in your garage, keen to have a chat! albo.sacco@gmail.com or answer here! 

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