Mallossi 177 kits on PX Discs

ok, im a young-un to the scene and am looking to do my first modifications i have ever done to an engine so’s as you can understand, im a wee bit nervous.

just wondering how easy th kit is to fit, how long it will take and considering that im not a spanner-monkey, will it be easy to fit?

im looking over at curare and hoping he’s got piccys hiding somewhere that’ll show me how…

any help and advice would be very much appreciated.

cheers ladies and gentlemen

i mean mallosi 166 kits by the way.

thanks curare, i appreciate it very much.

im probably going to get a new exhaust too but as i use my vespa daily as my work horse, it sits in the rain also so im going for a stainless exhaust. i was looking at the scootRS and JL stainless steels, any preference or difficulties in fitting etc?

thanks again.


oh, and plesse remember that i am a complete novice so you willl need to go into detail with technical aspects. i really want to learn and experience it all so i as unintelligible as i may seem, i am researching up and working things out as i get informed


Scuse my ignorance… (as usual) , but what’s the squish band ?

Check the squish band with the solder cable through the plug hole. You should have at least 1,2mm. If you don’t have this space you have to put a gasket under the head

oh and i hope your coming along nicely following your crash.

all the best,

Hi again,
The squish band is the area inside the cylinder head. It can be vital to modify this when tuning an engine. Some kits, especially the aluminium kits, tend to run more reliable with a slightly lower compression. You can remove a small amount of metal from the inside of the head to give a more ‚centralized‘ plug. Also, you may need to open the head slightly to accomodate a bigger piston.

I personally do not rate the Simmonini, especially for a kit. If you are going to kit the engine, get a pipe that will allow the engine to breathe properly, the Simmonini is really only for a standard motor. Still, there is always someone who will say differently!

Good luck.


hello xeres,

no need to be nervous, just do it slowly, and if you find some difficulty or not sure, before making a mistake just ask in this forum where somebody of more experience will answer.

1- I don’t advice you the Malossi 166 kit.
It is a good kit but if you don’t do heavy tuning it just doesn’t make sense.

2- Get a Polini 177 or a Pinasco 177. Polini is sportier and cheaper. Maybe pinasco last longer, but for the price difference when times come you can buy anothe rpolini.

Now how to mount it.

take the cylinder cowl off.
take the head off from the top end you are using.
take the 4 cilinder stud out. put two nut on and screw them one against the other… you know the method.
When the studs are away, take the cylinder out.
Put something inside the carter. Things tend to slip inside expecially when you are carefull.
Take the piston out and replace it with the new one that you find in the kit. CHECK THE PISTON IS ON ITS CORRECT POSITION WHEN YOU MOUNT IT. It will either have an arrow that points to the exhaust port, or consider that the window in the middle of the piston is opposite to the exhaust.
Then put some oil on the barrel and while with one hand you keep the ring on their position (there are two pins on the piston)
slide the barrel on the piston. If is the first time you do it you could find some difficulty. It will just take longer but you will do it.
Put the 4 cylinder studs back in and the head. Screw the head nut in a cross way, never thightening one but all proportionally. If you have a dynamometer set it at 18Nm. If not tight it well but not with all your strength.

Check the squish band with the solder cable through the plug hole. You should have at least 1,2mm. If you don’t have this space you have to put a gasket under the head.
DON?T SKIP THIS PART (as many do since they took it for granted they have the right squish band).

If you use the standard carb and standard exhaust get a 108 main jet.

Check the ignition time on IT mark or just slightly before. No more advanced then 18.

Start the engine and enjoy.

Hi Xeres, Have you spent all your hard earned cash yet? The advice you get from one person will be different from what you get from another, so talk to more people.
I have recently tuned a friend’s PX to Malossi 166, it is very relaible and can reach 80mph (that is approximately 130kmh). I have also known the Polini kits to blow up. The Malossi will not run at high speeds without the ports being matched to the kit. This is because the cylinder gets too hot on the exhaust port area.
I would suggest you talk to a number of people, especially those with years of experience.
I always use people like Taffspeed to get my tips. Taffspeed agreed with my tuning work for my friend’s PX.
It all depends what you want from your scooter. If you only use it for work, leave it standard. Or why not get a used PX200 engine instead. Cheap and reliable, and will sit at 65-70 mph ALL DAY LONG.
Good luck with what ever you decide, and reply if you want more info.
Mike (Happy House Scooter Club)[:)]

thanks for the advice Mike.

im actually a university student so i don’t have much cash to go round buying new bikes and expensive tuning but i just wanted to get a little more power and torque out of the existing engine.

curare reccomends the simonini with the polini 177 kit, what advantages does this system offer me?

my vespa is my only means of transport so’s i need this to be reliable too. i want to drive to Germany with it henec why i want the extra torque and/or power to carry the luggage and maybe an extra person (i live in the south of england so its going to be a fair distance).

its annoying as the vespa is used for both transport as a necessity and enjoyment.

i spend hours every week making sure my chrome-work is protected from rust and take it allof for the winter months. a timely drain on my studies i must admit but one full of pleasure to see her gleam on a bright summers day!

either way, at the moment im weighing up the odds of doing engine modification so i need to hear as much bad stuff as well as the good. if possible, could you talk me through a couple of other options, benefits and difficulties with setups?

thanks guys,



mikecollum correctly told you that you are going to get different answers from different people, and this is true. I just don’t understand how you are supposed to choose from all this different answers.
I personally know people with polini177 doing thousands km with the kit set with too much advanced timing and didn’t have any problems. Others in this forum (our friend Stubsy) had endless problems, and the same for the Malossi 166. For the big PX200 kit is the same story.
If your choice is going to be a choice dictated from an average survey, without considering all the other variable and mistakes often made by the people mounting the kit (not enough squish band, not the correct timing, not the correct spark plug grade, not the correct carb set up, and last but not least cronic bad luck) then the kits that are more reliable are made from Pinasco. They are made from alu, they cool better, they are less powerful and so they give you a wider margin of set up error.

Or you could ring:

In England: Taffspeed, PM…
In Germany: Worb5, Scooter&Service…
get all the answer and then choose the one that convince you (for any reason) better. So again it is you, the one with the less experience choosing from the answers all given from people with much more experience! Strange…
And another strange thing is that accepting or following one shop advice is like saying they know better then people who made the kit? How come?
So you see that if you really should do it well you shouldn’t do anything at all?!

Or make a survey on this forum. At the end whatever choice you are going to do if you will end up having no problem you will say you did the right one but if you will have some problem you will say you made the wrong one.

…I would be more concerned doing the right set up though whatever kit you will end up using.

I just will not choose Malossi for its power band that I don’t think it is good for the use you are intending to and because it needs case porting and bigger carb to really work the way it is supposed to.

And for whatever reason even after a miracoulous correct engine set up , for some woo-doo or bad luck you will break the kit you will choose, yes it will be sad, but it is not a life, you could save for another one contributing to the lives of people working at Pinasco or Malossi or Polini, that it is not a bad thing, and you will live with less stress and with less space for nevrotic synthoms.
You could break your engine even if you don’t touch it.
You don’t know how many times I saw a standard barrel sizing for the breaking of the oil pump device…

great stuff, thanks curare ill get right on it.


Mike-where are these cheap 200 motors?

I agree the 166 is a fine kit that can simpley be bolted on.However,I have also known of them to go tit’s up too.

I think it come’s down to the prep.As for the Polini 177 being crap?Well a straight bolt on,it’s far from ideal.But a little tidying up and careful building and it’s a far better bet for most than the Malossi.

For minimum work I’d go with a Pinasco.

As we’ve all conceeded tuning is a practice that’ll alway’s open debate as we’ll all have experiance of differant success and failure.

If they’re was the perfect set-up then we wouldn’t even be here talking about it,we’d all just point to X kit with Y exhaust and Z carb and jetting.[:look:] [;)]

oh, and does anyone know if the kits come with instructions?



I don’t advice you to spend money on a JL or other of this kind of exhaust if you are not doing the case porting, if you are not using a race crank and a bigger carb. Yes you will have an improvement but they cost a lot of money. Instead, expecially if you are using it for everyday, stay with the standard exhaust or a Simonini. The Polini 177 it’s preatty powerful bolt on unlike the Malossi.

good stuff, thanks for the advice guys!

just keeping my ear open is all, most likely, im going to be buying the polini kit, slamming on ScootRS stainless steel along with the bigger jets and what-not. (that or possibly the simonini pending peoples reccomendations!)

any adviceor problems fitting this? any other reccomendations on exhaust and how reliable is the kit?

cheers guys