Modern Vespa

I’ve had this project going on for a little while now, the concept is simple – a big bore water cooled 2 stroke auto engine into my favourite modern small frame, the Vespa LX.

All major components are Piaggio so everything’s reasonably compatible to bolt together. It’s straight forward enough project if you have the parts, time and inclination. My plan was to create a street racer with mid level tune, something a bit more aggressive than my daily ride.

Finished scoot is not much to look at with a mix up of LX and LX “S” trim parts.

The current tuning summary;
155cc 2 stroke auto
Full circle crank 55mm stroke, (3mm longer than stock)
Modified cylinder ports and timing,
60.06mm meteor piston,
25mm PHBL Dellorto carburettor,
Malossi reed block, manual fuel tap.
35mm modified exhaust
Modified Gilera runner airbox and Polini filter
Clauss Studio swing arm bushes
Mychron3
Custom wiring harness
Vespa GT radiators and custom water cooling system

Everything else is factory stock; clutch, gearbox, variator, brakes, suspension, ignition system.


Radiators tucked into Vespa LX frame. 2 stroke 155cc engine

From the side it looks like a poor example of any other Vespa LX, only it's a Frankenstein.


I don’t have a clue how to make a scooter look pretty, you can tell right? Instead, I just make it black.

This is how the project began.

I came into ownership of a black Vespa LX50 “S” 2T. The scooter had been dropped and dented and carelessly looked after by a first time scooter owner who wanted out of his painful experience. I was amazed it was a virtually brand new 2010 model, so after checking it wasn’t stolen, I took it off his hands for a bargain.

I discovered a 1996 Piaggio Hexagon which had been left unused for 5 years. This scooter has an engine that interested me, a water cooled 150cc 2-stroke auto. It’s Piaggio engine version is EXV1M. The following list of Piaggio auto engines are in this family,

Engine Piaggio Description
EXV1M 150cc water cooled 2 stroke auto
EXS1M 125cc water cooled 2 stroke auto
CSV1M 150cc air cooled 2 stroke auto
CSS1M 125cc air cooled 2 stroke auto

These engines were used in scooters such as; Aprilia SR, Gilera Runner, Italjet Dragster, Piaggio Skipper, Hexagon, Typhoon etc during the late 1990’s
Apart from the cooling method, mechanically the air and water cooled are identical. However the water cooled has variable advance ignition; 19deg at 1700RPM and 29deg at 7500RPM the pick up and CDI components are red in colour and labelled coil type 2. The air cooled scooters have ignition timing fixed at 22deg the modules are black in colour and coil type 1.


View of the other side. The Gilera runner airbox fits into a Vespa LX frame

Piaggio Hexagon. One hellova scooter

The Hexagon had 26,000 klms. I removed the engine, complete electrical and ignition system, the exhaust, the cooling system, and as many parts as I could reuse on the Vespa.

A closer look at the engine, one of the cylinder exhaust studs had snapped, to make matters worse someone had carelessly attempted a repair by drilling out the stud at a stupid angle which caused the flange on the exhaust casting to fracture.

I planned a complete engine rebuild. I pulled the whole engine apart, which was a learning experience. The piston and rings where heavily carbonised, crankshaft seals where leaking, the variator, front pulley, rollers, drive belt where totally worn. The clutch and gearbox appeared OK


Hexagon engine

Cylinder needed some repairs

Hexagon engine with cylinder removed, carbon build up at 26,000 klms

Oil seals needed replacement


Last edited by doniq on Tue Jan 10, 2012 3:36 pm; edited 1 time in total

The parts arrived from SIP, new main bearings, seals, water pump, pulleys, belts, complete variator, top and bottom end gaskets, piston and rings. I ground and polished the case halves in the induction and transfer areas and started putting the engine back together.

I ordered a full circle 55mm crankshaft from PM Tuning. I took the cylinder to Jason Tester of Precision Scooters who modified the port timing, sizes and transfer ports. He suggested and a 1.5mm cylinder base spacer.


engine rebuild parts

The original crankshaft, and the race crankshaft side by side. The full circle crank is counter balanced, and beautifully made, it has oil feed holes drilled in the small end.

case apart, transmission side

I decided to keep with the stock exhaust, but upgraded it by installing the SIP 35mm (inside diameter) stainless steel down pipe. I welded a bung for the EGT probe. This system has a good power band range it’s sporty up to 10,000RPM, It’s built with proper sound insulation and makes a pleasing exhaust note.


SIP down pipe and stock

Effin superb - love it

Rebuilding the engine


transmission side rebuild

flywheel side. Nice and shiny.

crankshaft going in

cases together now

rebuild pictures tell the story


Stator in place. Red CDI pickup is type 2 for variable advance

New Meteor piston

Cylinder in place

Cylinder looks OK

view of the intake without the reed block

Almost finished the engine rebuild


Piaggio EXV1M engine

Looks tough enough with the SIP down pipe.

I had to modify the Vespa LX swing arm to match the engine to frame.

This modification requires taking off 15mm in total length on the engine arm side, what I did was remove 7mm from each side to make a tight connection onto the bush. I cut a 4mm deep arc to fit the SIP exhaust down pipe.


Vespa LX swing arm is too long to match EXV1M engine points.

Engine arm width

Swing arm width.

I replaced the chassis side swing arm bushes with type from Clauss Studios.

Servicing the gearbox oil is tricky because the points are in a hard to reach place.
In order to refill and drain the gear box oil it’s necessary to remove the exhaust and rear wheel. There is no quick and easy way of checking the level. It’s one of the few things that I find annoying about the EXV1M engine design.
I never know exactly what the oil level is without removing all those things at which point might as well change the whole oil anyway.. I use motorbike gearbox oil 75W-80

The output shaft and rear brake drum of the EXV1M engine fit perfectly into the Vespa LX wheel, damn good thing too.


Gearbox oil is not simple like late model engines

Drum brake and output is perfect match for Vespa LX wheel. No modification. Too easy.

Got pics?

I knew they would fit.

GTS motor in LX is my next project.

I'd like a better shot of the radiator install too. Rad project.

Me too.

Yes indeed, pictures coming up.

I'll get to the cooling system, but in terms of steps in the project I did the electrics next which was probably not very clever since the wires got in the way later.


I modified the Hexagon electric harness to suit the Vespa frame, using schematic diagrams of Hexagon and Vespa LX for reference. Numerous cut and shut points to suit the length of the Vespa frame, switches, sockets, lights, fuses and connectors which I soldered and sealed with double glue wall heat shrink. In place of oil warning I wired a charge warning light. I kept the original indicator, brake, and lighting circuits but removed the main beam relay and connected the start button to a direct feed, I added an audible alarm for cylinder overheat.

I dismantled the thermo resistive temperature sender and modified it to become a K-type thermocouple. This gives an accurate cylinder head coolant temperature which the Mychron displays digitally. Sorry I did not take a picture while I was doing this mod.

The DC regulator went in the cavity space at the back left of the scooter, the fuse block mounted behind the leg shields, the starter relay, CDI module and ignition coil found their usual place.


hooking up electrics into the Vespa frame.

An nightmare of wires, but follow the schematics of both systems easy enough to hook up.

The cooling system.

I tried to recycle as much as possible from the Hexagon into the Vespa. I made a bracket to support the expansion bottle behind the top of right leg shield.

The radiator from the original Hexagon did not fit the Vespa LX frame, I attempted to size it up in different places, front, back, underneath the floor pan, nothing looked right. I started to wonder if two small radiators might fit into the space like they do in a large frame Vespa.


Hexagon expansion bottle fits into Vespa LX frame

Engine went in next - probably I should have cut the radiator space first, but I wanted to get some of the mechanical stuff finished.


Standing on it's own two wheels for the first time with the EXV1M engine in the Vespa LX frame.

I obtained a pair of Vespa GT radiators and measured the space left and right then used a Dremel to cut air flow rectangles into the steel leg shields. I made some brackets out of aluminum bar and used rubber bushes to secure both radiators nicely.

The radiators are pitched in and down and the exact position allows the floorboards to be removed.


Amazing what damage you can do with a Dremel

The cut looks rough here, I finished the job nicely with silver "U" moulding.

The cooling system interconnects – a frustrating task of the project. Lot’s of awkward angles and hard to reach cavity spaces, there is not much room in the LX frame with the radiators and pipes in place.

I got hold of a Vespa GT hose set which I modified. On the engine side I figured the routing from the thermostat housing using 20mm heater hose from a Toyota truck, it had perfect number of turns and switchbacks. The hot liquid travels through this to the front via 19mm rigid copper pipe inside the left floorboard space.

The coolant return from the radiator pair on the right scooter side with “Z” bends in the appropriate places to suit the water pump intake. The radiator pair connected together top and bottom of the expansion tank for supply and return.

During engine runs the cylinder head water temperature is stable around 60 Celcius without an electric fan and with the scooter stationary there is no overheating. I was impressed how efficient the Vespa GT radiators are.

In the future I will refit the glove box door with some cut away heat vents. I am currently using this space to secure the Mychron3 sensor hub. At some stage I will put the front wheel guard back on with a cut away modification or similar.

Finally getting it right, the finished cooling system does a great job of keeping the temperature stable. Job statisfaction.


Left side Radiator

Right side

Both radiators, from the back top view

Inside the engine bay, thermostat housing feeds hot coolant down and to the left of the scooter.

Floor boards can be removed with radiators in place. Positioning of radiators is important to allow this otherwise it is hard to gain service access.

horn cover access to top of expansion bottle. It's a tight squeeze in there.

bottom right of picture shows send as it comes down from the thermostat sending hot coolant through rigid pipe under the floorboards and to the front of the scooter. make sense ?

Coolant return from radiators via right side of scooter under floor boards and into the water pump

Looking good !

The original Vespa LX “s” leg shields where too skinny for hiding the radiators and expansion bottle and bits so I got hold of a standard LX inner leg shield and cut out both sides of the glovebox.


Vespa LX leg shields with glove box cut out and door removed

View of the radiator pair from the front

The carburettor I decided to use is the Dellorto 25mm PHBL. For lots of reasons, it’s a good balance of size and tune ability I wanted to match the intake manifold 30mm and airbox 40mm connections. The PHBL has manual choke control and easy to reach the 6mm main jet. I installed the Malossi reed valve block and a Malossi manual fuel tap and filter.

The Hexagon air box was too big and stupid to fit the Vespa frame so I got my hands on a Gilera runner 180 air box which fits perfectly into the Vespa LX. I am using a Polini filter element.

I wanted to run auto lube for simplicity but after a few test runs and a whole shit load of trouble with leaks and balancing it drove me mad, so it had to go! - I removed the complete auto lube system, tank, pump, control connectors etc. I am currently running 30:1 ratio.


Dellorto PHBL 25 - rubbish picture, brilliant carburettor

Manual fuel tap, makes things simple.

The battery, carby and cooling systems where primed and the post-rebuilt engine started and ran straight away, much to my delight. My initial impression from the first engine run is just how much more aggressive the engine sounded and felt.

With the engine running it was time to make sure the cooling system was cycling properly. I devised a way of bleeding air from the system by breaking the connection from thermostat to top tanks while holding it closed and letting the air escape past my thumb. Not an elegant method, but effective enough to remove air pockets. The radiators run warm evenly and by some miracle there did not appear to be leaks in other parts of the cooling system.

The moment I had been waiting for… that much anticipated first test ride.

Slowly at first, up and down the street near home making sure everything was safe and good. The brakes and suspension geometry all felt good. Back in the garage I went over everything double checking that all was tight and secure. No sign of leaks or things coming loose.

I started fine tuning the carburettor and airflow. I began with a 112 main jet, which was way too big. During trial runs I worked down to a 98 size main jet. The idle jet I have not changed. I combined all this with modifications to the air box using a series of 8mm hole drills which I opened and covered using gaff tape to adjust air quantity.


Engine bay - easy to access all the important bits.

The wife and daughter look happy the scooters running. "have you finished working on it now?" - "yes".... no.

I installed a Mychron 3+ which is a data logging dashboard that displays RPM, exhaust gas temp, coolant temp and wheel speed, lap transponder, etc. It’s a product from the go kart racing world that can be used on scooters too.

It’s very customisable for input types and alarms. It’s possible to view the logged sensor data into a laptop, which is a fantastic way of monitoring the engine, mucho useful in the final stages of setup. I fabricated a mounting bracket for the Mychron3 on top of the headset.


After each adjustment I made an identical route test ride, after which I download the sensor data from Mychron3 into “Race Studio” on the laptop, viewing the wheel speed, exhaust gas temperature, RPM and coolant temperature; all this helped me make tuning decisions.

The Mychron3 is a fantastic tool and a topic all unto itself, there are so many options and the manufacturer (AIM) has a massive product range.


Mychron3

Can store 1 hours worth of riding data for analysis

Along the way I tried to lower the gross weight of the scooter by removing things that I never use. For example, the kick start arm and mechanism, auto lube tank and connections saved over 1 kg of dead weight. Removing the kick start assembly also increases cooling airflow around the clutch and transmission.

If I say so, this scooter is quick. It’s got rapid take off from the line, the power band feels strong, hold the throttle wide open the engine keeps delivering. Without doubt the full circle crank makes a difference, at low RPM, or idle the engine feels slightly lumpy, possibly due to higher compression certainly the crank. Twist the right wrist and the engine runs smooth gaining quickly, at 5000RPM the power comes on in a big rush and keeps going. The maximum I have seen so far is 9000RPM and still accelerating. The exhaust makes a pleasing note a race exhaust system will produce higher RPM.

The scoot feels solid, it steers well and handles predictably. The brakes and suspension which are all factory specification do a great job. The standard LX front disc brake set up has more than enough stopping power. The rear drum does an OK job in conjunction with the front disk. The scoot keeps true to it’s small frame dynamic, light enough to make nimble switching turns, yet solid enough to keep a confident line at speed.

Like all scooter projects there’s always ideas for making things better. Things to modify and improve, maybe a Dr.Pulley race clutch and a whole long list of others, but for now I am enjoying riding my street racer.


Scoot safe.


The Vespa EXV1M - It’s a fast wasp.

Stunning

for this fabulous mod! It's great! Thanks for sharing.

Hi Donip,

I am from Viet Nam, I have the piaggio typhoon 125cc frame and now I want to set up the piaggio haxagon 180cc into typhoon frame. A bit confuse that is water cooler can put into this frame?

Thanks for your adv.

mail: binhpv79@gmail.com

Nice one !

nice project. what are the speeds your reaching?

Well, anything is possible if you have the time and money … and friends with a work shop and tools.
Your project idea is a good one, yes it would work but, it will not be a simple swap. You must consider the challenges, there will be a few to overcome.
The Piaggio Typhoon frame would probably have enough space to fit a radiator, the Hexagon radiator might be too big. You might need to use a fully custom built radiator, or two smaller radiators perhaps….You will need to design the airflow and make modifications to the panels, depending on where you decide to put the radiator. All the extra pipe work for the cooling system, and the expansion bottle, a few electrical things need to be added like a coolant temperature gauge.
The engine swing arm and rear suspension point dimensions are almost identical between the two scooters, the two engines also same dimensions.
You could convert your typhoon engine into liquid cooled by fitting an LC cylinder kit, Malossi 172cc for example, add water pump etc.

Hi Doniq,

TKs for your advise. I will buy the whole part of Haxagon 180cc engine from Cambodia or Beijing then bring it into Vietnam. Then put in in Typhoon frame.

Trouble is wiring and located the water pump and water cool.

Hope this project will be done soon. Im eager to tuning this into Typhoon frame.

U know, in Vietnam, the tuning part for bike is very expensive (Polini, malossi) so hard to buy it. I try to fix Typhoon engine but it seems damage all the parts that is why I want to buy another power engine to put in.

BTW, I m tuning the Piaggio Zip 4t 125cc and already change the cylinder (piston) 69. I want you advise how the weight of the roller should I set in. Currently, i do 3 rollers/9gr n 3 rollers/11.5g and also try 3 rollers/11.5g + 3 rollers/13.4g but the pipe shout very luod, it means the engine is power but the clutch is not fix wz the engine.

Let have a look my Zip my friend! http://www.bikervietnam.com/bfrm/showthread.php?t=280975

Tks 4 ur adv

Peaked 144 kilometers per hour, as recorded by the Mychron 3 using an electronic wheel pick up on a flat straight road, no other traffic around. I had about 3 litres of fuel in the tank and at the end of the run the light was coming on.

It’s not the sort of speed I attempt regularly as I am too old for fool stunts these days, however I was very impressed how stable and balanced the LX frame felt - not bad for a modern small frame, the scooter in its current configuration cruises easy at 110Kph – but being a modern 2 stroke, it loves a thrashing and it wants to keep going.

Recently I have been tuning for better rate of acceleration, I am at the limit with the stock clutch and saving for a Malossi delta, or a Dr Pulley if I can clear it with the financial controller (Mrs.Doniq)

The Hexagon 180 2T has an integrated water pump as part of the engine block, either driven from a belt off the crank accessible via the transmission cover, or from a bush in a housing at the end of the flywheel.
The Hexagon 180 2T was manufactured in small volumes, before they shifted the engine type into the Gilera Runner 180 2T and made it a proper sports scooter, and a very good one too. The Hexagon 1804T was produced in larger volumes. Make sure you get the correct engine for your project, and also make sure you receive the CDI module, regulator, wiring harness, air box and exhaust too.

What happens if the engine you import requires refurbishment ? You may consider the cost of rebuilding your Typhoon engine as cheaper option.

I can recommend you look at the forums on http://www.scootershack.co.uk which contain a lot of information of Typhoon 125 2T and Gilera Runner 2T with many owners tuning and modifying these scooters. I post there regularly.

[quote="doniq"] Peaked 144 kilometers per hour, as recorded by the Mychron 3 using an electronic wheel pick up on a flat straight road, no other traffic around.

in its current configuration cruises easy at 110Kph – but being a modern 2 stroke, it loves a thrashing and it wants to keep going.



Holy crap! that's killer.
See... I keep seeing awesome stuff like this, that makes my motors seem inadequate...
I love what you've done. The radiators fit so nicely tucked in there.
Sweet beans!!!

What rear hub is that?

Looks like a 10in split rim mounted to it.

Yeah, it's a 10 inch split rim.

I am currently running with the original LX rim.

Good project i am liking it a lot, but one thing i dont understand is why oh why did you not run a Malossi 172 bore for it as with you running a 55mm crank you weuld have a 183 in total, loads and loads of these setups are done here in the UK with the same speck.

Still it's a class vespa and no doubt will be fast, but that scooter is SCREAMING out for the that 172 barrel to be used in that, also with the parts you have in place you would get so much more gains out of them by running the tried and tested 172 bore.

But either way it's class, keep up the good work