i have searched and found may different answers that all conflict... i need some good info .

i need some ITBs in the 48-50mm range.. the bigger the better.. anyone have any ideas?

 

WELL, i just sold a set of cbr 954 itb's and they are 42mm at the intake side , so i would go with 929's or cbr 1000 itb's , from what i understand the only thing that you will find that are that big are going to be 1000cc and up .. hope that helps

 

yeah, i have some 954 tb's that are going on a b16.. way too small for what i need. from what i read 929 has 40mm.. i know gsxr 1000 and 1300 in that area, but noone can tell me for sure... and im not buying them to find out

 

the busa are 45or 46 mm at the plate and 48mm at the tip....there a few motorcycle shops that bore the itbs out to 48 at the plate butit was about 300 us or more to have it done

 

here's a list of all the Honda bike ITB's i could find . . . and it seems to me that 40-ish milimeters should be a decent size for most small-ish cylinders. think about it,

3019 square milimeters=area of 62mm ITR throttle plate
4536 square milimeters=combined area of four 38mm ITB's
5026 square milimeters=combined area of four 40mm ITB's
5542 square milimeters=combined area of four 42mm ITB's
6082 square milimeters=combined area of four 44mm ITB's
7854 square milimeters=combined area of four 50mm ITB's (like TWM)

also note:
1) itb's will flow quite a bit more than the stock manifold/throttle body setup, but at least in my research on the subject, 42mm seems to be a great size for medium to medium-hot b18 mills.
2) throttle plate area is not exactly proportional to flow, and most DIY ITB setups i've seen look like they would flow just a bit worse than a standard manifold+t/b at a given, low pressure, due to connections and joints used to mate ITB's to a stock manifold flange.

CBR600RR = CBR600F = CBR600F4 = CBR600F4i

CBR600RR 40
CBR929RR 40
≤'01 CBR954RR 40
≥'02 CBR954RR 42
CBR900RR FireBlade 42
CBR1100XX 42
CBR1000RR 44

most honda bikes were carb'd before about '98 or so, so make sure you're looking at fuel injection bikes. also, at some point around '01 or '02, Honda switched the CBR600's to 40mm plates; before that they were 38mm. somebody please confirm this as i seem to remember seeing it but i'm not sure.

 

remember that only one cylinder is sucking from the throttle body at a time wiht a normal manifold... so your comparison is kina flawed in its concept..

i know what im doing w/this and im not paying out the *** for pos twm itbs'' this stuff is going on an h22 btw

 

i just did that big post so that people would be able to search the info later, so no offence intended.

and yes, one cyl is sucking at a time, but it comes back to wave patterns/scavenging, which is probably really good on a stock engine, but i'd guess it's all messed up when we play with valve timing with cams and gears.

try hyabusa 1300. older ones i think are 43mm somebody said earlier that they've seen 45's, although i never have. other than that, maybe get a used set from a race team, or do individual carb's (maybe), but, i know, that's a pain in the butt. good luck to you.