Sprint mit Pinasco 177 Gaser Frage

[KTy]

Alloha

I have a Sprint 125 engine casing, the 3rd transfer has been grind, Pinasco 177 (the old one, not in alu), SI20/20D, original PX exhaust and points ignition.

I have tuned the carb with the jets that I had, but I find the result quite surprising;

Main jet is 160 BE5 112

Idle jet is 45/140, bigger will make the engine rattles a lot !

And the mixture screw is unscrewed for only 1 turn !!

What surprise me is the size of the idle jet,... If I unscrew the mixture screw for 1.5 turns, the engine rattles more at 1/3 throttle... :uargh:

mid and high RPM is fine, low-mid to high rpm is smooth and powerfull...

Any advices for my carb setup ?

[crazyduck68]

Alloha

I have a Sprint 125 engine casing, the 3rd transfer has been grind, Pinasco 177 (the old one, not in alu), SI20/20D, original PX exhaust and points ignition.

I have tuned the carb with the jets that I had, but I find the result quite surprising;

Main jet is 160 BE5 112

Idle jet is 45/140, bigger will make the engine rattles a lot !

And the mixture screw is unscrewed for only 1 turn !!

What surprise me is the size of the idle jet,... If I unscrew the mixture screw for 1.5 turns, the engine rattles more at 1/3 throttle... :uargh:

mid and high RPM is fine, low-mid to high rpm is smooth and powerfull...

Any advices for my carb setup ?

hi there,

first of all congratulations to the second place

please give us more details, for example, the sprint casings, when are they made?

why?..., a pre 1970 built engine is to small for the pinasco and your barrel will always get extra air!

do you use an original air filter on the carb or one with extra holes or non...?

the be5 is much to small you should use a be3, the 112 main jet sound too big for me, a rally 180 uses an 107...

[KTy]

hi there,

first of all congratulations to the second place

please give us more details, for example, the sprint casings, when are they made?

why?..., a pre 1970 built engine is to small for the pinasco and your barrel will always get extra air!

Interesting... It's GT VNL2T from 1967, what do you mean by "engine is too small" ??? The intake ?

I forgot to mentioned that I have enlarged a little bit (3mm+3mm) and smoothed the intake, and that it has also a home-made racing crankshaft (~15mm)

.

do you use an original air filter on the carb or one with extra holes or non...?

the be5 is much to small you should use a be3, the 112 main jet sound too big for me, a rally 180 uses an 107...

It's a carb from a PX, so it has the long air filter, with the extra-hole made ("heart").

I'll get a BE3, as for the main jet, I can put a 110, even if it's not so different.

What about the idle jet ? what about the air corrector (160) ?

Thnks

Bearbeitet 14. Juli 2006 von KTy

[crazyduck68]

Interesting... It's GT VNL2T from 1967, what do you mean by "engine is too small" ??? The intake ?

I forgot to mentioned that I have enlarged a little bit (3mm+3mm) and smoothed the intake, and that it has also a home-made racing crankshaft (~15mm)

the mounting for the barrel, there is a smaller gasket place, which means, that the transfers from the pinasco are bigger and get wrong-air there.

.

It's a carb from a PX, so it has the long air filter, with the extra-hole made ("heart").

I'll get a BE3, as for the main jet, I can put a 110, even if it's not so different.

110 sound more reasonable to me.

What about the idle jet ? what about the air corrector (160) ?

the idle jet is not bad, and the air corrector also.

[KTy]

So, back on this one,

I am now running 160 BE3 110 and 48/160. The mixture screw is about 0.75 turns, BUT it is an old SI20/20D with the "small" screw, not the one found on the more recent PX. The tip of the mixture screw is shorter and also less conic, I hope it explains the 0.75 turns.

Altougth, from 0 to 100% throttle, slowly or fast, the engine is very smooth and "feels" good, there is a little rattling if the throttle is *constantly* opened to 15-20%.

Going back to BE5 is worse, so I may want to check the timing...

Does anyone know what is the recommended timing for the old icast-iron Pinasco 177 ?

Spec is: GT engine with 3rd transfers, SI20/20D, original PX exhaust, points ignition and cast-iron Pinasco 177.