MeltDownZ
Registered
After extensive research, trial and error, I have virtually eliminated all of the low-end surge from my bike. It took about 2 months, and many, many hours. Most of my info comes from professional tuners and mechanics. I thought I would share what I’ve derived. The diagrams below give a visual for my info. Keep in mind that I use my busa for a lot of commuter driving so my goal was to get a smooth ride not horsepower or track times. Many folks ask about smoothing the busa out and there’s a lot of disjointed info so I’m going to summarize it all. I fully expect JohnnyCheese to say most of what I’m presenting is BS but his viewpoint is welcome. He’s got a lot of good info.
The main causes of surging are:
- the busa’s nature to roll on/off sharply at low rpms
- poor fuel mapping
- idle being too low
- excess throttle play
Sharp roll on – even with a well mapped bike, the busa likes to roll on/off hard. Huge performance engine, relatively light bike, it's in the design. This gives the uncertain feeling of not knowing exactly how the power’s going to kick in during low rpm throttle roll-ons. The TRE can help here by adding a short roll-on before the main power kicks in. It also smoothes out the roll-offs. This little amount of gradual roll on and roll of give you a much better feel for the engine at low rpms. So, I recommend the TRE as part of an optimal smooth setup. Explaining why it works opens a giant can of worms so I’m not going to touch that.
Poor fuel mapping – a poor fuel map will give you minor surging or sputtering through the low rpms. A good fuel map all but eliminates this but doesn’t address the sharp power kick in. Just the same, I recommend the PCIIIusb with a good map as part of an optimal smooth setup. The PCIII is better than the PCII because it controls the fuel jets directly and can map at 250rpm intervals. The PCII has only indirect control by means of fooling with the bikes computer readings of the engine conditions.
Idle too low – The primary surge effect comes from the engine quickly jumping from low rpm to the target rpm. By ensuring the idle is not too low, you’ll reduce the amount the engine jumps. Adding to this is that starting a roll on in low rpms is kicking in the engine where it has the least amount of torque. This also contributes to a kicking from the engine. With a higher idle, the engine has already built up a little torque and provides a smoother roll on. I like running my idle just a little bit higher than stock at 1,300 rpm.
Excess throttle play – When there’s too much play in the throttle cables, you’ll have a tendency to hit the surge wall too hard. Too much slack allows your roll-on motion to begin followed by a 'bumping into' the throttle pull. Your slight rolling momentum into the tension pull is what causes an increase in the kick. With very close attention to your throttle control you can avoid this. However, ensuring that throttle cables are properly snug, will eliminate this effect altogether. With the busa, you’ll always need good throttle control. However, proper throttle cable adjustment will ensure that the power comes on gradually from the moment you start to roll on without an unnerving delay.
A note on chain adjusting… Do NOT try to eliminate roll on/off surge by tightening your chain. A chain that is too tight will damage various, expensive, transmission parts. A well lubed chain however will make everything feel slightly smoother.
And last, correcting one of the above solutions without the others may produce a greater surging affect making the discovery of the issue even more ellusive. Although the TRE seems to work regardless of the setup if smoothing out things is your goal.
I’ve drawn up the following diagrams to show how these things affect the power curve.
<!--EDIT|MeltDownZ
Reason for Edit: None given...|1091714030 -->
The main causes of surging are:
- the busa’s nature to roll on/off sharply at low rpms
- poor fuel mapping
- idle being too low
- excess throttle play
Sharp roll on – even with a well mapped bike, the busa likes to roll on/off hard. Huge performance engine, relatively light bike, it's in the design. This gives the uncertain feeling of not knowing exactly how the power’s going to kick in during low rpm throttle roll-ons. The TRE can help here by adding a short roll-on before the main power kicks in. It also smoothes out the roll-offs. This little amount of gradual roll on and roll of give you a much better feel for the engine at low rpms. So, I recommend the TRE as part of an optimal smooth setup. Explaining why it works opens a giant can of worms so I’m not going to touch that.
Poor fuel mapping – a poor fuel map will give you minor surging or sputtering through the low rpms. A good fuel map all but eliminates this but doesn’t address the sharp power kick in. Just the same, I recommend the PCIIIusb with a good map as part of an optimal smooth setup. The PCIII is better than the PCII because it controls the fuel jets directly and can map at 250rpm intervals. The PCII has only indirect control by means of fooling with the bikes computer readings of the engine conditions.
Idle too low – The primary surge effect comes from the engine quickly jumping from low rpm to the target rpm. By ensuring the idle is not too low, you’ll reduce the amount the engine jumps. Adding to this is that starting a roll on in low rpms is kicking in the engine where it has the least amount of torque. This also contributes to a kicking from the engine. With a higher idle, the engine has already built up a little torque and provides a smoother roll on. I like running my idle just a little bit higher than stock at 1,300 rpm.
Excess throttle play – When there’s too much play in the throttle cables, you’ll have a tendency to hit the surge wall too hard. Too much slack allows your roll-on motion to begin followed by a 'bumping into' the throttle pull. Your slight rolling momentum into the tension pull is what causes an increase in the kick. With very close attention to your throttle control you can avoid this. However, ensuring that throttle cables are properly snug, will eliminate this effect altogether. With the busa, you’ll always need good throttle control. However, proper throttle cable adjustment will ensure that the power comes on gradually from the moment you start to roll on without an unnerving delay.
A note on chain adjusting… Do NOT try to eliminate roll on/off surge by tightening your chain. A chain that is too tight will damage various, expensive, transmission parts. A well lubed chain however will make everything feel slightly smoother.
And last, correcting one of the above solutions without the others may produce a greater surging affect making the discovery of the issue even more ellusive. Although the TRE seems to work regardless of the setup if smoothing out things is your goal.
I’ve drawn up the following diagrams to show how these things affect the power curve.
<!--EDIT|MeltDownZ
Reason for Edit: None given...|1091714030 -->
. Don't bet 
