One more fuel injection question

MsHap · Post by **MsHap** » Sat Feb 16, 2008 2:20 am

ok the TBs I got have a vacuum activated valve hanging off them.

Is it for the return to the tank? Is the idea that the return releases the pressure from the rail when the bike is off?

Oh, also, they have a second set of butterflys with what appears to be a stepper with it's own board attached. What is there actual purpose? Cold starts?

sickle44 · Post by **sickle44** » Sat Feb 16, 2008 2:45 am

Can't answer the Vacuum ? for you Chrissy, but the second set of flys are to basically smooth out transitions. After apexing a turn and you then are getting ready to stand it up get on the gas, if you're riding agressively you hammer the throttle while it's still over part ways. With the precision of FI this would have you either in a high/low side after the violent jerk you caused youself with the throttle hand. Of course, bike company's don't like law suits so, the second fly valves are told to open progressively or shut slowly(in throttle chopping incidents) by the ECU to smooth that whole transistion out and make it feel like a good old sloppy carb which could never supply air and fuel nearly as fast as an FI unit because of the vacuum that's gotta build and increase?

Get it, got it, Good?

You never did tell me what kind of TB's you got, but I'd be buyin' a manual from the bike they're from which hopefully should tell you what your mystery vacuum line is? They weren't from a Cali bike were they?

MsHap · Post by **MsHap** » Sat Feb 16, 2008 2:59 am

they are from a gsxr 600 I think.