Big bore on Saturno 500 Bialbero

[geronimo]

I am looking to go for a big bore conversion to my Saturno by using a Nordwest engine, so I don't have to mess up the original motor to do this.

Does anybody know if the Saturno head will fit onto the Nordwest cylinder barrel without engineering modifications and if so, what the resulting compression ratio would be? Also, I assume that the Nordwest head gasket would have to be used.

I know that the Nordwest cylinder head would be the ideal way to go but as this involves considerable frame and tank modifications to fit in the twin carbs, I am very reluctant to cut the bike about as it is in beautiful standard condition and I wouldnt want to move away from this.

I just want a bit more low down torque rather than sheer top end power and think that the big bore and a bit more compression would give me this.

Any help would be appreciated; thanks

[Joachim]

I am looking to go for a big bore conversion to my Saturno by using a Nordwest engine,

Good idea. So you will not have to modify the Saturno case or the Nordie cylinder.

The head will fit. Of course you have to take a Nordie head gasket.
But you also have to modify this one to make it fit to the Saturnos head.
The water channels are different. If you don't make some extra holes it will end in overheating the engine.
Have a look at the pics in this article

viewtopic.php?f=1&t=4059&p=26915&hilit= ... ung#p26915

There is a great article from HP about Saturno tuning in the forum, but it's only in german. Can you handle this?
And it may be worth thinking about also using the Nordies valves, rocker arms and cams...

ciao joachim

[geronimo]

Thanks Joachim, my German is not too good but the pictures are vey helpful,

Regards
Geronimo

[Joachim]

and you can always ask here

ciao Joachim <just wondering wether none of the real specialists has answered yet>