Vespa CATERPILLLAR!! i love torque....

[knoker]

Hi guys!
now, i try to explain my new project that i'm going to realize......
at last time, my totally original Primevera motor doesn't run correct, it has some problems....so i must realize a new travel motor for city use! i'd like to realize a motor with a lot of torque, a motor that not rev too high, but has power and torque at low rpm.

this is the component that i'm going to assembly:
- 130 DR
- crank Mazzucchelli like special lip (it's a mine realization) and 53 stroke! so, it becomes 135cc and has a little timing increase.
- reed valve Polini with 24 carburetor
- Parmakit ignition (1,6 kg)
- 27/69
- exhaust Proma

what do you think? i'd like to receive your advice....
bye bye.

P.S. soon photos

[Juan]

53mm crank?Are you swapping the 'rod or using an eccentric pin?

My thought would be the use a Malossi reed block as I think the Polini ones are rubbish.I'm not familiar with Proma exhausts but the chaps on ET3.it seem to rate them highly.

[knoker]

i use the eccentric pin!

proma il a little better than a polini "banana"...do you know it?

i think that Malossi reed valve il too expensive for city use....i prefer polini....

[Juan]

Yes I know the Polini banana,a good little pipe for the money but ugly.Does the Proma look similar?

Out of intrest,where can you get the eccentric pins?

[knoker]

Proma is very very similar!

i find the eccentric pin here:
www.uvageneration.com/denis.htm

this is an italian tuner, he produces also some pinios for vespa gear:
23 and 25 for 24/72
25, 26 and 28 for 27/69
28 for 29/68
so there are possible a lot of variations in ratio
he produces also a 3rd and a 4th gears short

[curare]

hello knocker,


I am not sure about this configuration.
I love torque too, but it is not that with a 125 or 135cc you can have a lot of torque and a good street engine at the same time.
Let's put this way: 125 or 135 is a small engine, trying to get out of it as much torque as you can is ok but at the end will definetly be missing some breathing and loose power.
The DR has simple design transfer and giving the option of reed intake I don't feel is a way to go. Reed crankcase inlet is better then rotative only if you fully take advantage of it expecially on the cilinder configuration ( boost port/s).
My absolutely personal view is that this would not be a globally satisfying engine.

[Juan]

Thank you for the link unfortunately I can't read Italian. :-[I think Denis has helped me on ET3.it before so I shall message him over there later.

Congratulations Max,do you have any pictures from your French adventure?Was the Lambretta from RS tuning?They produce stunning looking machinary.

[knoker]

Hi curare! Congratulations for your winning!

i understand your perplexity, but i think that i have only one way: i have to try this configuration, because i had just buy a lot of this components...

do you have some advice or modifications that i have to do, for this components?

i'm going to modify the transfers of crankcase like the transfers of cylinder, and i'm going to enlarge a little bit the exhaust port (1mm for each side and down until to the top of piston);
53 stroke (1mm beetween cylinder and crankcase) increase timing but also a little bit.

only in a second time i'm going to change cylinder.....now i have to use the 130 DR.....

what do you think about?

bye bye. thanks for attention.

[curare]

tank you juan and knocker, I don't know if you red this in other forum since I wrote for 20sec, and then modified my message, I can't beleive you have had even enoughtime to reed i! What I wrote was in this subject for 20sec!!
I don't have pictures of the event, was a climbing mountain race, but, I can't really say anything except for the engines that we made. I just know from what they told me, I dI don't know anything about the others and maybe we won the first, second and third places just because the other competitors did not have enough engine?on't really know, for this reason I cleaned my writing after 20 sec.
What I can say our engines were highly tuned but absolutely not race spec.
The first place was won by a Polini177 longstroke reed... second was M1, reed, hammerzombi modified, third another polini 177.
For what I know the race starting was given by another scooter the other following, pace car style. For what I was told there was a good lambretta with a good pilot that unfortunately crashed out very soon. It was a kind of opened class for any kind of tuned engine lambretta included. I really don't kow anything more. Just made the engines for two clients (got first and third), have to say the one got first was a better specification. The second place was done by my young meccanic (on M1 ). First time on vespa and on small frame. (only 200km with it).

Knoker: since I don't have experience with your configuration and mine are just considerations maybe the good way to go is trying and then modifying according to the results? Then just start from what you have reported.

[knoker]

at first, thanks for your advice Curare!

i have others question:

- what do you think about a modified exhaust port like this ?
on the left the original form; on the right the modified form


or is better the traditional enlarged form?

- and about the carburator, is it too big? i think no, but what do you think?

- some advice about crankcase modifications?

i take this photograph from your site Curare, i have to do this modification (green zone) in my crankcase?
i use reed valve

bye bye. thanks

[MiNiKiN]

I would not make the top edge that straight, piston rings will not last long.
I would suggest something like this:

with a small transition radius of 0.5 to 1.0 mm around all edges, to ease the ring slipping in again. The more oval you shape it the smoother the kick @ reso, when the pipe starts loading. The more rectangular the more dstinct power increase will be (but likely less band)

[knoker]

i had this idea for the exhaust port because i see this file on web:
www.vespaonline.it/download/cil._2ves.pdf
take a look...
this file refers to a 102cc but i think this modification could be a good idea

[curare]

OK juan, open another topic for the GS.

knoker, I can't say better then minikin.

The T or eyebrows port (even though is slightly rounded on top), it is true that in the past was used by many manufactures but today is extremely rare. The advantages using this shape are really questionable but it is sure that this shape is very arsh (the worst) on rings and piston too.

The 24 for your using I think is too big I would go for a 21-22 at the most.

[knoker]

to Juan, this is a photo of my Proma...


ok Curare, i have understand that the T exhaust is a bad solution because it is dangerous for piston rings and also for piston.
how much i have to enlarge the exhaust port at the top?
i think about a width of 36,5mm.

bye

[knoker]

knoker said:

- some advice about crankcase modifications?

i take this photograph from your site Curare, i have to do this modification (green zone) in my crankcase?
i use reed valve

bye bye. thanks

[MiNiKiN]

The pipe is pretty good, in fact it was the best you could get in the early 80ies. Exhaust width around 36.5 to 37 is still very safe.

I cannot see a need to go for the full machining ala curare on a DR130. But who knows, maybe not that much. Just cut the corners...

[tony]

minikin said:

I would not make the top edge that straight, piston rings will not last long.
I would suggest something like this:

with a small transition radius of 0.5 to 1.0 mm around all edges, to ease the ring slipping in again. The more oval you shape it the smoother the kick @ reso, when the pipe starts loading. The more rectangular the more dstinct power increase will be (but likely less band)

how i do em too minikin.

[Juan]

Just been looking on Italian eBay and there's an old school Proma listed.The old style look much better.My problem with the snail systems was always the muffler on the end pipe.They look shit but the plain exit pipe looks fine.

All about aesthetics here I'm afraid.

[knoker]

knoker said:

knoker said:

- some advice about crankcase modifications?

i take this photograph from your site Curare, i have to do this modification (green zone) in my crankcase?
i use reed valve

bye bye. thanks

Hi....anything else about this question?
like Curare said, i think i'm going to use reed valve with 19 carburator...
bye

[knoker]

at now, this project is stoped because i'm waiting DRT gear products....
when i receive all the products i'm going to start to assembly the motor...
bye