Malossi 166 vs Polini 177 for PX 125E

Hey guys! Just registred in the forum. My name's Ricardo and I'm from Portugal.


Here's the deal, i found some older posts in the forum but neither of them had exactly what i wanted to know so listen up:


I'm wanting to pump up my dear PX 125' engine, and i'm kind of undecided about the setup.

As here in Portugal almost nobody uses the malossi 166 kit i can't get enough info about.

I'm a daily rider in the city, but i do take a lot of long rides.

My goal would be an engine with a lots of good torque (rally 200, px200's like) because i usually take luggage and travel with two persons, that could make a nice top speed (70 mph - 120km/h) but balanced, this is, without excessive consumptions (6L/100km's max)

I've tried the Pinasco (same option about PX200's stock) but i think it's not sportier enough to what i like and i find it to be a little boring to drive around.


My setup plans are:

option 1:

Polini 177

dellorto SI 24/24 carb w/ autolube

23/65 gear

eventually longstroke crank and T5 pipe.


option 2:

Malossi 166

Mikuni 26 mm or Keihin 24 (hope to get better response with a carb like this) without autolube

23/65 or 23/64 gear

again, eventually racing crank and T5 pipe.


If you could give me some review info about the malossi it would be very apreciated! Setup, performances, consumptions, pros and cons ;)


So, again, torque, medium top speed, medium consumptions, what's my cylinder kit? :D


Thanks! Best reggards,


Thanks La Rocca, real helpfull ;)


I Think I'm going for the polini, for everyday use, and longs tours and all...altough I'll keep in mind a race project for the malossi eheh


Thank's again, Aufwiedersen[;)]

Well, as promised!


The engine runs perfectly! 


Polini 177

Serie Pro Longstroke crank (really well made, nice job!)

Keihin Powerjeted 26mm carb

Exhaust pending (still chosing one)


I have already runn in the kit, and the engine reveals to have lots of "go" power! Just yesterday it topped 120km/H on the GPS and got there pretty fast.

The stock exhaust must be replace or you won't be able to tune the carb properly for the idle and low revs and it will cut most of the high rev power.

Anyway, I'm satisfied and I'll update you when I get an exhaust!


Thank you for your time, cheers!


You´re welcome !


Let me know how the engine runs !



By the way, just one last question, what's the diference beetween this 3 products?


Mazzuchelli Longstoke crankshaft:, Art.Nr.46000000 :

Mazzuchelli Longstroke crankshaft: Art.Nr.46005000 :

And the Serie Pro Longstroke Crankshaft: Art.Nr.46003000 :


Is the second more polished and improved than the first? 

To the Serie Pro the con rod diferent?

what's the main diference from the Serie Pro to the Mazz?

So, I have came to realise that to take full profit of the Malossi I had to go into a High Tunning Project, and that's not really my goal. 


I'll have the Polini 177, match the cases and porting, and get an engine with a very nice torque and low mid's, with enough top end. A long ride touring, and daily rider with that bit of Sport driving to it.

I wanted to ask you guys about a longstroke crank: is it really worth it? I mean, i have driven a Polini 177, with longstroke and really enjoyed it, but is the diference that much for an optimized regular crank?

Either case, wich is the best upgear? 23/65? (again, with Cosa clutch or PX200's?)


Thanks to all answers ;)


Best reggards,


No one? come one fellas, give me some advice please!

Hi dude



Ok - i try it [^o)]



I dont understood exactly what your question is, i guess you want to know the difference between the 166 and the 177 ??



1. Polini 177 - basically it´s a tourqe cylinder. If you mount it you have to pay attention for all details like carb. ignition etc. because the 177 is very sensible. The risk of a piston jam is higher than the malossi.

With a longstorke crank you have more torque and more horsepower because you create more volume. Recommended gear Primary 23/64



2. Malossi 166 - This is a high ref monster ! If you build an engine with the right setup you have to pay attention that you´re not fly away when you push the gas [:P]

I recommend you  a big Carb. reed valve intake and an italian exhaust.    Recommended Gear 22 dents clutch.




hope this was helpfull

Hi dude


sounds great man !!!

I guess i`ll build again a polini 177 engine beause it´s so funny !!