Join Date: Mar 2018
Motorcycle: Suzuki GSF1200SZ
GSF1200S Weird AFR with dynojet stage 3 and KN
I have 2005 gsf1200s bandit, europe version. I've removed system that injects air into exhaust (plugged holes on engine block with special kit), installed aftermarket muffler, K&N air filters (RU-2922), Dynojet stage 3 jets spring and needle kit (E3351). I had to play around with needle setting and idle adjustment screw in order to get it working normally, first it was done according to Dynojet manual and it was awful because it had no thrust and was terribly firing (i.e. with real fire) from exhaust pipe...
I had different feeling compared to what it was before, however I considered everything was ok. I had to make myself confident about opening full throttle very fast - it was not working good, I've found a solution for rapid bike acceleration by opening throttle bit by bit relative to speed, full throttle result in not good thrust and opening it as RPM are growing allowed faster accelaerations that it was before.
This week I've installed Haltech WBC1 wideband O2 kit with gauge. I've calibrated it on open air as per instructions.
Now the problem is that with warmed up engine I'm getting 11:1 AFR while crouising (<4000rpm), then it gets to 14.1 at 6000rpm and then rapidly falls to 17:1-18:1 above 7000rpm.
I would expect bad tuned carb to be rich only or lean only througout the rpm range and there are methodics described over the web on how to deal with that, however I can not find information on how to deal with part rich part lean operation. Could someone give me a link on how to tune carbs in this situation?