EVO2 Piaggio cilinder

tiba_karotsu

OVERREV TUNING
I just went through the ports this afternoon & by nightfall it was finished, this's an EVO2 Piaggio cilinder tuned to stage1 & it's solely for road use, it's for MikkoR's Zip SP & he's the Polini distributor in the Philippines. i really like this cilinder better than the PR2 b'coz the EVO has bigger transfer ports as cast so this has better potential for power output, i shall post the stock port timings tomorrow when the shop opens.

here are some pics below for your viewing pleasure, enjoy!

EVO2%20001.jpg

EVO2%20002.jpg

EVO2%20003.jpg
 
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I do hope so b'coz they will be tuning the whole set-up not me, MikkoR just asked me to do his cilinder he'll be using this for touring (imagine that a race cilinder for touring), he'll also be using an EVO8 pipe (the whole set-up will be purely Polini) in conjunction with a 21mm carb that's why i didn't alter port heights.

now it will be a question of whether he wants his carter tuned as well.
 
....Hi tiba, i'm looking forward to see it perform on mikkor's project piaggio Zip SP....A full Polini spec touring Zip SP.... :) ....Btw i hope we'll finally get our hands on a Zip SP by next week, for sure you'll be working on it.... *D
 
you've done a really nice job on that block tiba......I have the same kit but for minerelli and I totally agree with you about the transfers being larger than the MK. The only thing that I'd do differently is what I did to my kit, which is make those auxillary exhaust ports a little bigger. I know you don't want to fuck up that block and that it'll only be for mid-race, but still. As long as you don't make them any taller than the main exhaust port, everything will be chilly. Damn I wish I could get this digital cam to work to show you what I mean. Anyways, pretty work, hope it runs nice.
 
can you show any other photos please?

i think that version is bad.... evo1 tuned go faster then evo2...
 
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evo1 v 2

ive ran the piaggio evo 2 50cc lc cylinder now for 1 ,1/2 years and have made bigger gains than with the earlier evo 1
i run enlarged auxillary exhaust ports which provide me with the required port area without running excessive port durations which still provides a wide enough power band for the transmission to hold peak power revs effectively throughout the speed range due to the lower torque the 50 makes
the transfer area also allows for lower durations to be more effective
ive taken moulds of all the ports and found the transfers from base to cylinder walls although large do have there faults that require filling rather than opening up although opening up at the case area helps resolve the problem and maintain a good venturi as the entry is almost the same size as the exit as standard
the auxillary exhaust ports also have problems,the cylinder window gives a false area calculation due to the narrow choke point as the port passes the cylinder studs casting area which are tricky to open up to the required size as its easy to break through
the cylinder spigot also interrupts high rpm flow from reed to lower transfers and needs work to open up the flow path
nice to see you resisted opening up the exhaust port to the manifold Tiba,
better to match manifold to port on this cylinder.
 
hey some of you may not know me very well but i'm not a noob when it comes to porting & tuning i always think things over first before i do the first cut on the cilinder ports & in this case all the ports needed a good clean up, when you look closely at the exhaust port you'll still see the overlapping nikasil plating intact but i just went over it with an oilstone to smoothen the surface but the transfer ports received a major clean up so removed some overlapping nikasil plating in there which takes up area (also with the aux ex).

the thought of opening up the exhaust port outlet never crossed my mind i always approach tuning cilinders with great conservation take a little step everytime you change something to try out but thanks for the reminder it's the thought that counts. :)

if this cilinder were meant for racing i will definitely change port timing. here's another shot showing the transfer ports.

EVO2%20005.jpg
 
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nrg69 said:
can you show any other photos please?

i think that version is bad.... evo1 tuned go faster then evo2...

which part do you want to see?

have you tested this cilinder on the dyno yet? do you know anyone? it's b'coz it's not a butterfly exhaust port doesn't mean it's not going be faster, ports alone won't make a scooter fast there are too many factors to consider.
 
Ok here's the list of the parts that im going to use:

Evo2 Cyl kit
Evo 8 Pipe
MK Pro Crank
Evo 6 Variator
Polini Speed Drive
Polini Kevlar belt
Dellorto 21mm carb
Polini Airbox
Polini Reed Cage
Metrakit New Ignition System with Lights
MK Pro Bearing and Oilseal kit

yes carters will be tuned to match the transferports.

its just going to be used for touring, as for the gearing, i think i will change this last.

My current set up now is:
Mk Sp2 cylinder kit
MK Pro Crank
Evo 6 Variator
Polini 2G clutch
Polini Kevlar belt
Polini For Race 3
Stock ignition, stock cdi
21mm carb with stock stock airbox with malossi airfilter

Right now its top speed is estimated at 115kmh with just the carter tuned to match SP2 transfers, cylinder kit is completely stock. I think with the new iginition at portings on the SP2 in can reach 120kmh easily.

But my target now is to reach more than 120kmh without reliabilty problems, so i opt for the new evo2 cylinder kit since im a big fan of that exhaust port design (VERY RELIABLE) . My MK SP2 is 1300km plus old and yet i havent replace any rings yet, power is still the same up to now.
 
that's right why don't you change gears? that way the engine doesn't rev too much when you're touring.

as promised here are the port timings on a stock EVO2 Piaggio;

main ex port 195deg
aux ex ports 192deg
main trnsfr 133deg
sec trnsfr 132deg
boost port 118deg

note that these timings are taken with the 0,50mm squish clearance subtracted from port height.
 
tiba_karotsu said:
which part do you want to see?

have you tested this cilinder on the dyno yet? do you know anyone? it's b'coz it's not a butterfly exhaust port doesn't mean it's not going be faster, ports alone won't make a scooter fast there are too many factors to consider.


i have on my scoot the old evo, and i was be crazy to pass 22cv on my dyno...
many different head, homemade exaust, very different port timing and dimension of ports ,many test with carter soluctions, valve ecc ecc ecc ecc

it is a very fast evo in my country, but i think that mhr is the best for the 70cc class

about polini evo2, i think that it isn't a speed cyl, its impossible to do 22cv with that cyl...
the transfer is egual to polini 1, the head is a bad polini 1...and the exaust with booster on scooter can't work well.
 
nrg69 said:
i have on my scoot the old evo, and i was be crazy to pass 22cv on my dyno...
many different head, homemade exaust, very different port timing and dimension of ports ,many test with carter soluctions, valve ecc ecc ecc ecc

it is a very fast evo in my country, but i think that mhr is the best for the 70cc class

about polini evo2, i think that it isn't a speed cyl, its impossible to do 22cv with that cyl...
the transfer is egual to polini 1, the head is a bad polini 1...and the exaust with booster on scooter can't work well.


"many different head"

Did you only trying?? Why don't you design it well, so you don't have any surprise..
You can even simulate exhausts before making them needlessly! You can save time and money!

"exaust with booster on scooter can't work well"


?????

Please explain to me?
 
Cylinders with auxiliary exhaust ports can have higher port area than butterfly shaped exhaust ports. This means that an cyl with "boosters" in the end will be more performant than the butterflyed exhaust cyl.

Tiba: why have you subtracted 0,5mm squish clearance from the port heights? That is not right, you should subtract only the cylinder deck clearance (from piston top at UDC till cylinder top).
 
roost said:
Tiba: why have you subtracted 0,5mm squish clearance from the port heights? That is not right, you should subtract only the cylinder deck clearance (from piston top at UDC till cylinder top).
On an EVO deck clearance is equal to the squish clearance.
 
Jasper V said:
On an EVO deck clearance is equal to the squish clearance.

Correct! EVO cilinder heads have no built-in squish clearance like MHR/MHR Team cilinder heads, MHR Team heads have around 0,15mm built-in & MHR heads have 0,60mm squish clearance.
 
Browni said:
"many different head"

Did you only trying?? Why don't you design it well, so you don't have any surprise..
You can even simulate exhausts before making them needlessly! You can save time and money!

"exaust with booster on scooter can't work well"


?????

Please explain to me?

i don't understand what you tell me...

at the moment i have tryed:
4 different head, different cr and emisferical camber ecc ecc
2 different valve, with a lot of different reed and many different internal insert.
6 different exaust, polini 5,6,7 malossi team 03 and 04 and finally the homemade that i have now on my scoot.
a lot of carter soluctions, different primary ratio, profile ecc ecc

on my dyno evo original do 17,5 cv... now my evo do about 22cv...


scooter isn't a bike for Gp... the exaust exit is small and there are the two "prisoners" (one by side) who limit the width of the culvert to the inside.
the booster cannot extend correctly in width, and do not work correctly on a cylinder for scooter.
the "double exaust" is the only solution for a scooter speed cylinder.



the 2fast has ""double exaust"" + booster, is all an other thing!!!
here we are comparing a cylinder with ""double exaust"" to a cylinder with exaust + booster!


ps: ciao roost, a te piace il nuovo evo?? secondo me è proprio una buffonata...
 
Tiba: Ah, I see. I don't really know the evo.

nrg69: you are right, the cylinder holding bolts limit the width of the boosted port exhaust, they limit even the width of the usual butterfly port.

Neanche io credo che questo evo2 dovrebbe essere il sucessore del normale evo. Praticamente hanno fatto un passo indietro, paragonato alla malossi che con il 7T ha fatto un passo avanti.
 
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