Re: 95 CBR900RR carb, need different needles
Bladeracer: pressure gauge would do no good, in order to test if the engine is flow limited I need to be able to run at full throttle. As I mentioned, it's leaning out and falling on it's face before I even get the throttle blades half open. Does that sound like air flow limited to you?
Gang two cylinders per carb: a 38mm carb is too mall for an IR on a 289, you need at least a 42-44mm to not be flow limited. Also ganging two cylinders is tough, to do it RIGHT you want to gang cylinders that are 180 degrees apart in the firing order, which on a V8 is tough due to the odd firing order.
Two banks of carbs: again 38mm not big enough to do IR, and twice as many carbs means twice as much tuning, synchronizing carbs is a hassle, lots of reasons to not go IR period.
Four carbs feeding a plenum, think of it as an inline four-barrel Holley. After all, the four barrels of a Holley all have their own metering circuits, it's effectively like four carbs with each pair sharing a fuel bowl.
I've considered taking the needles out, but seems like a pointless exercise, as it won't run right (will be way too rich down low) so why try it?
Rustedroot: Yes I shimmed the needle as much as possible, it did make an improvement, but not nearly enough. This helps lead me to believe that the needle is the problem.
Slothman: Yes the 289 makes more power than the CBR900, meaning more fuel and air. One important limiting factor here is needle and seat area on the fuel inlet valve. I have already considered that problem, and concluded it's not a problem. The CBR900 is gravity fed, the fuel level being 1ft above the carbs would yeild about 0.25PSI of fuel pressure at the carb. Liquid flow is proportional to the square root of the pressure difference. If 0.25PSI is enough for 200HP, then four times that (1PSI) will flow enough fuel double the power (400HP). I've tested these carbs up to 4.5PSI with no leaks/problems, so I'm running them at 2 PSI to have a margin of safety and still have plenty of fuel flow. If I do have fuel starvation problems, they will not show up until I've had my foot to the floor some time, not as soon as I tip the throttle in.
The second part which again you don't seem to be grasping is that on the bike each carb is only feeding one cylinder, and each cylinder is only drawing air on the intake stroke, and doing nothing the other 75% of the engine revolution. Therefore, these four carbs can feed a 200HP engine (your number) while only flowing air and fuel 25% of the time. With a common plenum intake like my tunnel ram, they are feeding air 100% of the time, so they can feed 4x the power (800hp). I think judging by the size (38mm) and some other research I've done, these are well suited for up to 400hp. If that doesn't click, think of this, on a V8 each cylinder draws air 90 crank degrees apart, with an intake stroke duration of 180 degrees, so at any given moment only two cylinders are drawing air, and when one is at peak airflow the other is just getting started or finishing. So I effectively have four carbs feeding 1-2 cylinders, that's effectively over 2:1 carbs per cylinder, that's over double the 1:1 carb per cylinder when it's on a bike.
I've had a Holley, I know more about Holley, Edelbrock, and Quadrajet carburetors then most people know about any one carburetor. Because of what I know about these carbs, their limitations, their 60 year old design, is one of the main reasons I picked these more modern carburetors.
My main reason for starting this project is I wanted to run a tunnel ram intake manifold, but didn't want to cut a hole in the hood and deal with two Holley carburetors. I started looking at side-draft carburetors, most of what's typically used on cars like Webers are uber expensive, and still ultimately old designs. I picked up these carbs from eBay for $20 with shippping, and they were in perfect working condition.
Trust me, I've put far more thought and research into this than any of you guys, so how 'bout you stop questioning my intentions and just answer the question, if you can that is. Your arguments are all things I have considered, thought through, and concluded that there is no fundamental problem with what I'm doing. I'm open to honest curiosity, but if all I'm going to get is nay-sayers then obviously I've come to the wrong forum for technical information.