I need porting advise

[Mexicano]

I got a new Malossi 120 c.c. cylinder and piston, I will use my 48 m.m. crank again, I have the port map (from stock cylinder) and all the info related to ports opening and closing.....I need help to port my cyllinder and get more HP's...I will appreciate advise from EXPERTS here, I'm willing to pay for the "job"...please P.M. me.

Or better if some one (stablished tuner) want to receive my cylinder, do the job and send it to Mexico by UPS or FedEx.

Thanks!

 

[roost]

What are the port timings?
What kind of exhaust port you have? (single, butterfly, ausiliary exh. ports...)
Because the exhaust area is the one that tells most on the state of tune of the engine.

 

[Browni]

What are the port timings?
What kind of exhaust port you have? (single, butterfly, ausiliary exh. ports...)
Because the exhaust area is the one that tells most on the state of tune of the engine.

I think it has got a simple oval exhaust port. And the standar port area is really very small.

 

[Mexicano]

Yes, the port is a round small one... bore is 57.5 m.m. and stroke is 48 m.m.

Here is the port map:

http://i34.photobucket.com/albums/d101/MomoMexicano/PortMapMalossi.jpg

Exhaust Port STARTS opening at 80° (going form TDC)

Transfer Ports STARTS opening at 105°

Transfer Ports FINISH opening at 135°

Exhaust Port FINISH opening at 145°

Exhaust Port STARTS closing at 140°

Transfer Ports START closing at 135°

Transfer Ports FINISH closing at 100°

Exhaust Port FINISH closing at 75°

 

[roost]

Are you sure? By the data you gave you should have like:
Exhaust port duration; 202°
Transfers duration; 148°

So this would be killer port specs.

 

[Browni]

Are you sure? By the data you gave you should have like:
Exhaust port duration; 202°
Transfers duration; 148°

So this would be killer port specs.

SOmething is wrong, or this is a high-end cylinder!

 

[Browni]

Yes, the port is a round small one... bore is 57.5 m.m. and stroke is 48 m.m.

Here is the port map:





Exhaust Port STARTS opening at 80° (going form TDC)

Transfer Ports STARTS opening at 105°

Transfer Ports FINISH opening at 135°

Exhaust Port FINISH opening at 145°

Exhaust Port STARTS closing at 140°

Transfer Ports START closing at 135°

Transfer Ports FINISH closing at 100°

Exhaust Port FINISH closing at 75°

How long is your conrod? 100 mm??

 

[Mexicano]

Roost & Browni:

I'm possitively sure about the measurements on ports...I did it 4 times to be sure, and took the port map twice, my conrod is 86 m.m. from center of small end to center of big end.

The cylinder is Malossi M3111374 stock....the exahust port is very small compared to a 70 c.c. high end cylinder, isn't it?

 

[Browni]

Roost & Browni:

I'm possitively sure about the measurements on ports...I did it 4 times to be sure, and took the port map twice, my conrod is 86 m.m. from center of small end to center of big end.

The cylinder is Malossi M3111374 stock....the exahust port is very small compared to a 70 c.c. high end cylinder, isn't it?

47-23 mm=24 mm is very much for an exhaust port height! Even if the top of the piston is in a 2-3 mm heighter position than the bottom edge of the port!

These type of big bore cylinders are made for max 10000 rpm, for example, the 180 cc Runner, has a 6500-7000 rpm maximum power and it has got approximately 20 mm heigh exhaust port!

If your exhaust port opens 80 degree from the TDC this is very much port duration!


Usually a high-end 70 cc cylinder (stroke=39,2 conrod length=80 mm) has a max 20-22 mm heigh exhaust port!

 

[lilplaya_bm]

what i would do to this cilinder if i needed more power and rpms from stock would be from the widest point of the oval and up i would squar to the hight of the exhaust now...then raise the center of the exhaust port up to around 20 degrees. this will give your more rpms and alot more torque especially at the lower rpms.... the transfer port openings look cool but may need redirecting of gas over piston...the exhaust port modification should be enough... using hte right pipe would be the main thing though...i would use c16 or hebo r4...i think it will work perfectly...aswell as a 32mm pwk or makuni...and a great crankcase....

what does your crankcase look like? that would be a nice thing to look at before u port your cil...and how much compression is there above the piston...and is the cil iron or aluminum?

 

[EGT]

The 70 cc pipes like the C16 and Hebo R4 will definitaly NOT work on this cilinder!

Why not buy the pipe made for this cilinder of Malossi, or maybe take the Jolly Moto big bore version.

Don't you have a higher resolution of the pic?

 

[Mexicano]

EGT:

Here is a higher resolution pic:

On the pipe side....there is not in the market a pipe for Aerox 100 but Leo Vince ZX, which I have now(derestricted), the Jolly Moto for 125 c.c. is for Gileras and do not fit my engine, unless I cut the downpipe and make it fit but not sure about it.

My compression ratio is 11:91:1

Any advise is wellcomed

 

[Cruz_e_Silva]

what i would do to this cilinder if i needed more power and rpms from stock would be from the widest point of the oval and up i would squar to the hight of the exhaust now...then raise the center of the exhaust port up to around 20 degrees. this will give your more rpms and alot more torque especially at the lower rpms.... the transfer port openings look cool but may need redirecting of gas over piston...the exhaust port modification should be enough... using hte right pipe would be the main thing though...i would use c16 or hebo r4...i think it will work perfectly...aswell as a 32mm pwk or makuni...and a great crankcase....

what does your crankcase look like? that would be a nice thing to look at before u port your cil...and how much compression is there above the piston...and is the cil iron or aluminum?

Please read above and what you wrote also...this is a 48mm stroke 120cc engine not a 39,2mm stroke 70cc. I think what you meant 20 degrees is 20mm and that would give 214º degrees exhaust timing...crazy timing for a scooter that doesn't have a specific exhaust.
Raising the exhaust port doesn't give lower rpm torque...instead it takes it from the cilinder.
And I can't see how you can see inlet port angles to say the gas needs redirecting...
I don't know much on the engine subject but I try my best...when I see a post from you on this forum the first thing I think is how much crxx you will write in a line of text. You don't need to reply to all posts on engine tuning, please learn something on the subject and read some books like 2stroke performance tuning from Graham Bell and some of MacDizzy's pages.
Then come and discuss it with the rest of the people.
Best regards and sorry to be so direct.

To Mexicano...
I think you are missing something (measure piston to deck clearance) or that cilinder will revv the well of your crank and pipe.

 

[Mexicano]

Cruz e Silva:

My deck is "0", I mean, the piston has a dome and the dome comes out of the cylinder, the head is shaped to accept the dome, the cooper gasket gives it an extra room for the dome but deck is "0", cylinder head volume is 12 c.c., head gasket thickness is 0.020", top ring land height is 0.045", piston dome volume is 1.92 c.c.

Thanks!

 

[lilplaya_bm]

Please read above and what you wrote also...this is a 48mm stroke 120cc engine not a 39,2mm stroke 70cc. I think what you meant 20 degrees is 20mm and that would give 214º degrees exhaust timing...crazy timing for a scooter that doesn't have a specific exhaust.
Raising the exhaust port doesn't give lower rpm torque...instead it takes it from the cilinder.
And I can't see how you can see inlet port angles to say the gas needs redirecting...
I don't know much on the engine subject but I try my best...when I see a post from you on this forum the first thing I think is how much crxx you will write in a line of text. You don't need to reply to all posts on engine tuning, please learn something on the subject and read some books like 2stroke performance tuning from Graham Bell and some of MacDizzy's pages.
Then come and discuss it with the rest of the people.
Best regards and sorry to be so direct.

To Mexicano...
I think you are missing something (measure piston to deck clearance) or that cilinder will revv the well of your crank and pipe.

the degrees and mm thing ar right..i wrote wrong thing...but i didnt say that gas definetly needed redirecting, i sadi it MAY need redirecting....
if u did know anything about cilinder or two stroke tuning then u would know that if u raise the center of the extaust port higher then the rest and make a triagle shaped port then when the piston is on its downstroke that when the gas flows out of the exhaust port in the center first then it will push the pistone down hard then having the exhaust port open all at once... all at ounce is for a late power band... opening center will give better throttle responce and lower to midrange power....but if u use a good gearratio then the power can be be broader then normal...also if u open the exhasut in any area then it will increase rpms....but this directs the rpms to low end and midrange....

also i post on the scooter section to help people with technical questions so they would have to listen to someone like u trying to be a dick...
and fuck your books too...i have read any books about wo stroke tuning except a book about cilinder porting...every thing else is easy...i have one of the faster bikes were i am from...so y question me? it just makes u look like an ass!!!
good luck in porting mexicano!!!!dont listen to this ass!!!!

70cc or fabrizi 90cc pipes would be fine for the amount of rpms u will be putting out...and that jolly moto pipe only has to be cut twice...its notto hard if u wana go that route!!!

 

[Eoin70]

lilplaya its a known fact that raisning the exhuast port will result in less torque

you are decreasing the length of the Power stroke hence your reciprocating force is much less

also Mexicano:

did you take into account the length of the stroke into your port duration calculations?

 

[Cruz_e_Silva]

Mexicano...you should definetly make a specific pipe for you engine.
Browny calculations are correct and in a 120cc you will be getting arround 12000-12500 peak power rpm...it's a lot for a 48mm stroke streetbike.
I can see you have the know how to at least design a better pipe for your bike.
If you want help please PM me as I can see that some "pro" are only making conversation..

 

[Eoin70]

from my calculations i can see he only has 174 degrees exhaust port duration

the size of the port is 23mm right?
so divide it by his stroke 48/23 =2.06
then 360/2.06 = 174 degrees

or maybe im doing it wrong

 

[Mexicano]

Nuno: thanks for the advise!

Eoin70: Yes I took into consideration the stroke, in fact my numbers come from a degree wheel mounted on the crankshaft, piston and cylinder mounted too.

Thanks to all!

 

[lilplaya_bm]

lilplaya its a known fact that raisning the exhuast port will result in less torque

you are decreasing the length of the Power stroke hence your reciprocating force is much less

also Mexicano:

did you take into account the length of the stroke into your port duration calculations?

eoin - it is a known fact that if u raise the WHOLE top of the exhaust port equally then u will definetly loose lowend power and move your powerband to be later....it is, also, a known fact that opening your exhaust port in any area will increase rpms to different areas of the powerband...the difference between me(someone who has a little experience and a few trial and error cilinder) and u(someone who dont know fuck all about tuning exhaust ports except for what he hears online in a forum) is that i know were to open my exhaust port and around how much i have to open it to achieve my desired powerband.... i am not saying im the best in the world but i sure as hell know more about it then u and cruz_e_silva... so when u both get some experience in tuning cils then try and question my ideas and help people interested in tuning...untill then piss off...
mexicano- if u dont believe me then ask a friend of yours who does tuning...your a mechanical engineer, u should be able to explain scietificly what i am trying to say...i dont go into to much of he science and theory behind everything...i jus buy really good parts, modify thing that need to be modified, and then tune everything together...the porting of this cilinder looks fine anyway and doesnt really need to be touched unless u want a little more power out of it(what i said to do)...alls u really need is a great pipe, in your case would probably be a 90cc fabrizi or a handmade pipe..i still dont like leovinci with that cil....
good luck!!!!