Fuel Injected GPZ550

First off I know this has been asked a couple times and the general consensus is that the 550 is too small for the available throttle bodies. So please before you post up saying it can not be done read what I'm asking then answer. If you still feel strongly enough that it is not possible please explain why do not just say it can not be done because it has not been done.

Now that I have that out of the way. What I am curious of is whether using the 38mm throttle bodies off an early GSX-R600 or R6 would be feasible? My plan is to install the 615 kit in this bike with a set of aftermarket cams. Since both motors will end up roughly the same displacement it would seem to me the throttle bodies should work. Is there something I am missing as to why this is not a viable option?

I would rather not get into the cost portion yet so if we could leave that out for now I would appreciate it. I know it will not be cheap but I am not too worried about it yet as I am still in the planning stages.

Thanks in advance

Don't know if you could get your Head to flow the #'s of the GSX-R. That would be the Bottle Neck. But the engine will only use the air it can pump through. Since your not trying to get a signal in a carb venturi, you could Map the, what Micro-Squirt, to handle the Air. It might bog if you open the throttle at a lower RPM though. I'm sure you can Roll On and get it to run hard.

Maybe look into pulling the throttle bodies of of a small injected European bike. I am pretty sure the euro ninja 250 has been injected for a few years. They may be better suited for your challenge. Then lots of math research, more math, and a pile of cash it might work.

You have to look at the engine as an air pump which is exactly what it is. So knowing this we can assume a two things. The first being that two engines of similar displacement will have similar air requirements. The second is that the manufacturer of the donor bike has already done the math for you. These two assumptions go out the window when the RPM range of the donor bike is extremely different than your project bike. A 2012 R6, CBR, ZX or GSX-R is going to require much more air at 15500 RPMs than my GPZ will at 12000 RPMs.

Motor Head is correct that the GPZ head will have very severe limitations compared to more modern head designs. But if you can get the head to flow well and keep intake velocity high this becomes less of an issue. I am sure there are several very talented head porters and if anyone can recommend one I would be very appreciative. Hopefully whichever machinist I use will have some recommendations for cams and cam timing.

As for the fuel computer I will not be running a Mirosquirt controller. It was my original plan but I stumbled onto a forum for hacking ECU's. My plan now is run the ECU, wire harness and fuel/air delivery system from a donor bike. This will make the tuning process much simpler since I will just have to fine tune what is already loaded.

Check member Larry Cavanaugh for your head work and engine combination info.
www.cavanaughracing.com/