Torque engine for PAV40

[edumegacc]

i want to build engine base in px125 cases. is to carry pav40. 1 or 2 person

 

I wanto to use Pinasco crank 62mm , box exhaust and carburator S.I 26/26 or maybe S.I28.  I allready have pinasco flytech in engine.

 

i need you help to decide to choose good torky cylinder. in my head i have this:

 

- pinasco magny cours : will land in +- 126/176 timings. i allready made one in 60mm crank and is really power in low and medium rpm

 

- Vmc stelvium : really power in medium and high rpm in 60mm stroke. will have good timing in 62mm stroke

 

- bgm 177: never install

 

- malossi sport: never install

 

what you choose? why? if you have dyno fantastic please show!

[Nakkl]

Stelvio no experience so far, but will built my next engine on and us a SIP 60/110 crank.

BGM with 60/105 and BB Touring exhaust has power everywhere and from below, pretty sure this will easily handle such higher load;)

What gearbox setup do you have?

[Angeldust]

BGM177/187cc rotary valve with 60mm PX200 BGM Touring crankshaft (casing milled for wider 200cc crank web).

Cylinder with opened up transfer ports at the base, matched casing. 
Exhaustport and diameter NOT modified.
Raised compression (12.3:1)
Std. port timings (~172°/122°, no base gasket, only 5mm Spacer to equalize longer rod of 200cc crankshaft)

Exhaust BigBox Touring (BBT)

Measured in 3rd gear.

Pulls easily a 24/62 straight primary gear on PX125 EFL gearing.

 

 

 

Compared to some Polini221 setups

RED: BGM177 rotary valve

GREEN/BLUE: Polini 221 rotary valve

 

 

 

 

 

Bearbeitet 27. August 2020 von Angeldust

[BerntStein]

i would reduce to BGM vs Stelvio.

Had both. both o.k.

Most Important is to do the setup carefully. Not just throw parts into the engine !

if you want slightly higher revs and more ground clearance, the polini exhaust will be handsome to setup.

page 33.

the small lth box , i had first , wouldnt fit your purpose. then i took the polinibox.

the rotary valve had 117 and 67 deg

cylinder timings slightly altered.

23 65 is optimum for me. you could choose 22 65 gears.

si24 carb and optimized the intake channel.

standard bgm crank with 5mm cut off to be open longer. 21 hp at 6800 rpm roughly with the vmc. and 122 176 timings.

the bgm will be similar.

 

[style63]

You could gain even more torque with a reedvalve inlet and 30mm carb without too much finetuning (as needed with rotary valve).

60mm crank is good für reasonable timings.

[edumegacc]

thanks for your reply

 

 angeldust : 26nm is amazing congrats

 

I like RR box but is not switable for this Project, i agree.

 

i see in fórum one engine with pinasco magny cours and crank 62mm and 23 hp and good curves but can not find it....

 

the is some dyno with bgm and crank 62mm?

 

regards

[style63]

You can achieve this with BGM and 60mm crank. I think 23PS/25 NM is no problem.

[edumegacc]

Polini box or bbt? what will go better with 62mm crank and timings +- 175/125?

 

regards

[edumegacc]

After open engine i see that valve is scratch... so reed valve will be...

 

In my mind quattrini m1xl with 60 crank... but what? Full circle or bell or like original?

 

Thank you