Fine tuning my Polini 177

[morbin]

Hi all,

I'm building up my engine with Polini 177, 63,5 GS piston (180,5cc), SI24 little ovalized, ori puff & GSF kopf.

I measured the following data without fudi and calculated the others:

Which timings do you think I should go for to obtain best results?

Gruss

Matt

[freakmoped]

are you sure your calculation is correct?

i get these figures with normal stroke 57mm

1fudi A174 Ü118 V28

1,5fudi A176 Ü123 V 26,5

[morbin]

are you sure your calculation is correct?

i get these figures with normal stroke 57mm

1fudi A174 Ü118 V28

1,5fudi A176 Ü123 V 26,5

I doublechecked my calculations and my values seems correct.

Ü value for 1,5mm fudi keeps coming 120,2°, all the others are about the same...

later on I'll try to measure values again...

[Brosi]

Your calculations are correct. I´m not quite sure wich timings fit the ori puff best, but i guess 1,5 mm fudi´s timings might be to big (esp. 120° transfers). So i would rather go for the 1 mm...

[freakmoped]

yes. i would also prefer the 1mm fudi

for drehschieber

[morbin]

I'll go for the 1mm fudi then!

I tried measuring with a 0,5mm fudi and data is ok. I measured again einlass period and measured little longer than before (113nOT-63vOT).

Gravedigger told me that 1,6mm of squish is fine but for best results I should go for 1,2mm... Now, to do it my way I'm considering to go for 1,4mm

In this case I have to mill 1mm for the fudi + 0,2mm for the squish = 1,2mm.

The Malle head has only 0,8mm of headroom so I think I'll have to mill the whole 1,2mm from the top of the cylinder...

With this squish and my calculations RC should then be around 12.

Quite high for my experience, will temperature increase too much?

After looking around I'm thinking about 160-BE3-125, min 55/160, timing 18°, spark B8HS, correct?

Any suggestions about carburation, timing and spark plug?

Matt

[freakmoped]

correct yes

i don´t know the exact data of the cylinderhead

but i prefer 1,6mm squish for drehschiebertuning

less is often more

[morbin]

correct yes

i don´t know the exact data of the cylinderhead

but i prefer 1,6mm squish for drehschiebertuning

less is often more

I should mill 1mm then...

Very well then, I'll keep you informed!

Thanks a lot,

Matt

P.S. should I change jetting with an adapted T5 ori puff and\or a RZ Right?

[morbin]

At last I had the cylinder milled for 0,8mm (I took away the 0,2mm Polini gasket and used a 1mm homemade gasket at the bottom) and closed the casings.

Latest results say 173°-116° timings, 1,6mm squish and 11,8 RC...

Here some pics:

I'm really looking forward to turn it on, hopefully during this weekend...

[KTy]

I would have enlarged even more the admission... But you're going the safe way

[Johnny13]

So whats up? It's tuesday already !

[morbin]

So whats up? It's tuesday already !

It's Wednesday and no chance yet... (

KTy, safe sex for me

Anyway enlarging the admission where?

[morbin]

I put it in and gave it a short ride.

Carburation seems correct and after heating up engine feels quite mild on temperature. At idle it is shaking a bit like a P200.

Low rpm power is ok, probably with such an inlet time the high RC helps a bit, mid power feels good but then stopped revving...

So far a nice engine to ride

[Johnny13]

Congratulations !

[scorpion]

Hello, my name is Michael.

[freakmoped]

Hello, my name is Michael.

nice to read from you mike :wasntme:

[morbin]

what's up Mike?

[scorpion]

zur Aufklärung:

wollte damit nur meinen Respekt gegenüber denen signalisieren, die so gut englisch können.

Das war der einzige Satz, den ich kann! (

[morbin]

zur Aufklärung:

wollte damit nur meinen Respekt gegenüber denen signalisieren, die so gut englisch können.

Das war der einzige Satz, den ich kann! (

[KTy]

what's up Mike?

What's up with the unique Italian Spark Magnifier user ?

[morbin]

What's up with the unique Italian Spark Magnifier user ?

Doing good

What's up with you Brilliant French Electronic Mind??

OT Right now I'm not using it, it has been giving me troubles on my P200 lately... Right now I'm using an homemade sparkplug wire (a "geology" wire) with a mask around it connected to the ground... KTy you should give it a try

Bearbeitet 11. August 2006 von morbin

[KTy]

OT Right now I'm not using it, it has been giving me troubles on my P200 lately...

It is almost sure that it is related to the connectors or wires, it happens to me too... Check this out: http://www.germanscooterforum.de/index.php...t&p=1288154

You can also try to slightly increase the spark plug electrode gap...

Right now I'm using an homemade sparkplug wire (a "geology" wire) with a mask around it connected to the ground... KTy you should give it a try

I will certainly when I have more time... !

[morbin]

Damn! I had a little heat seizure today.

Was riding with my girl on little uphill and engine turned off... it was only a little heat damage, but damn!! damn anyway!!

Maybe I should've checked jetting better; now I have put in 50/140 min, and 128 max just to be sure... didn't try it yet, but I'll have to be more careful... :(

Life's so hard sometimes my friends...

Btw as I don't have a BE2, is 140-BE3 fatter than 160-BE3?

[freakmoped]

Btw as I don't have a BE2, is 140-BE3 fatter than 160-BE3?

yes

[morbin]

I believe I should change the title of my post into "learning my Polini" at this point!

Practically, when the engine is hot it is very hard to start it, even pushing the Vespa downhill. And when eventually it turns on, it stays on only with throttle wide open. At this point it gains rpm only by tilting the Vespa on the left side...

Moreover there is a disturbing sound coming from the engine that fades a lot when pressing the clutch...

Mmmm... :uargh:

[morbin]

I disassembled the engine but could not see a defective clutch oilring... the crank came out too easy from the clutch side bearing though...

Here some pictures I took, the engine had about 150 km...

http://img227.imageshack.us/my.php?image=dscn2784ym8.jpg

http://img55.imageshack.us/my.php?image=dscn2785vx2.jpg

http://img55.imageshack.us/my.php?image=dscn2790bq6.jpg

http://img140.imageshack.us/my.php?image=dscn2791sz4.jpg

http://img225.imageshack.us/my.php?image=dscn2794wc3.jpg

Was it burning gearing oil too?