Hi Guys,

I'm located in Australia and recently got my CBR650F de-restricted with a ECU flash and tune.

They also removed the 02 sensor and the restriction from the velocity stacks.

I got a full Yoshi system and DNA air filter installed as well.

Now, I love the power it's making (nearly 80hp) but have noticed something that's bothering me.

No matter what rpm I fully twist the throttle at, the response is very jerky like it has to think about it.

This doesn't happen if I slowly twist the throttle however, only if it's suddenly snapped back.

I told the dyno shop where I got it done and he seems uninterested and said the process comes at a cost.

Does this sound right to you? Should I take it to another dyno shop for a second opinion?

Does anyone know why this could be happening?

Thank you in advance.

Benyamin.

 

Why did they remove the O2 sensor? That is a crucial input to the PCM for fuel control. When you crank the throttle the throttle plates open and the motor takes a huge gulp of incoming air, making the mixture very lean. The PCM has to quickly respond with fuel/timing. What is the tuner using for fuel control other than MAP, TPS, IAT, ECT?