Pinasco 177 setup

Is there anyone who can help me with setup on my 125 VNA 1959. After installing Pinasco 177, SI 24/24 and racing cranckshaft (ignition and exhaust are standard) i do not think it goes any good (75 Km / h). Is there any adjustments that should be made.




Please allow the questions... what else did you do with the engine besides what you posted?


- You propably have a different motor case, because you mention a SI24/24 carb ...but on an original VNA1M-type engine you cannot fit Dell'Orto's SI-Type carburetors...


- Did you change the primary transmission in order to convert the extra power of the 177 also into extra speed? Unless you don't do that, something about 75-80 km/h seems normal for a VNA engine.

- did you put a modified bigger clutch/hardened cruciform into the engine?

- Did you overwork the original ignition (new points & capacitor) and check timing? This is mandatory in this case.


- An original VNA comes with 8" tyres...please consider that with 10" you can get a higher speed...

- also why do you keep the original exhaust? On 2-stroke engines you should always see the engine as system where every component from the bottom to the end, has to work harmonically with the others.

...speaking technically: If you put a bigger carb, a racing crankshaft with longer inlet timing and a bigger more powerful cylinder on the motor, it is only logical to fit an exhaust system which is suitable to the new components. With the original exhaust (throttling the whole system) you definitly don't let the horses run free...

Sorry, but only changing the carb box does not have any use, as the opening in the crankcase is still small and throttles the system(A system is only as strong as it weakest member) order to get a real effort of the SI 24/24, you must strip down  the whole engine and rework it, regarding the crankcase inlet opening.

But I meant something else: An original engine case for a VNA has no possibility to put an SI type carb on it, as the original VNA has a direct inlet into the barrel, whereas the carb intake socket is mounted...if you have a carb box and an SI Carb fitted, it means you have an engine case of a different type than a VNA...
so which is then the engine identification number of the casing you have?
Unless you don't get the SI 24 carb to really working, it might not be a big advantage to put a SIP Road (normal sized version of this exhaust) on it.



I have changed the carburettor casing so the SI 24/24 carb fitted and a new stronger clutch. and i will also change the primary transmission.

What exhaust do you recommend?