so with a 48 weber ida, you have a couple choices, 48mm 51mm or if you're nuts 58mm gene berg



when you switch to efi, 48is hard to find, they kinda start at 56mm and go all the way to 62mm



how do you choose the right one?



engine in question is a PP 12a, trying to maximise power under 8k, for reliability redlines going to be about 9, 9500...

 

The throttle body size has a minimal effect on fuel injected engines, as long as its not too small. ITB's make the engine even less bothered by big throttle bodies. The 750cc gsxr has 4 x 42mm throttle bodies. The only thing you really lose with too big of a throttle body is low rpm range. It may only take 25% of the throttle travel to give the engine all the air it can breathe at low rpm. Can be a little touchy to drive at low rpm, but thats about it.