Sure it is a good idea to add a little fuel even to a 100% stock bike but it will not change a thing if you do not.
This is just more of that urban anti E10 legend stuff but has No bases in fact.
Smitty, What you say is true. People won't watch a meltdown happen in front of their eyes. You are absolutely correct that no 1 change will hurt an engine. What I am going by is the accumulation of several factors which when added together will add up to enough change that would cause a person like myself to be very uncomfortable.
These are some of the reasons why I feel the way I do. Some are actual Facts and some are just very strong beliefs that I base on experience.
1) Even a 2008 bike (OP's model) has a factory tune (map calibration) to meet EPA standards at the time it was built. It was a closed loop tune and the A/F calibration was done with fuels of that day which were not E10 fuels.
2) The oxygen sensors used on our bike is a narrow band sensor that can only read a/f ratios in the range of + .3 to- .3 of stoich which for non- alky fuel is ~14.5:1. Therefore the window limit of adjustment for a narrow band sensor is absolute tops => 14.1 to 14.9. Pure ethanol is something like 9:0 stoich so when we run E10 fuels we must recalibrate our A/F ratio by .3 of 1 point.
What all that means is our stoich is now 14.2 and no longer 14.5 when we run E10 fuels. Just from the E10 fuel ALONE, we have reach the adjustment limit of our closed loop system. Everyone keeps saying "it will adjust", "it will adjust". But it can't adjust anymore than it has due to the E10 fuel .
3) Look at any HD VE map. The Front VE look up tables on our bikes are close to 10% lower than the rear cylinder VE tables. At any given time the front cylinder is running leaner than the rear cylinder by a bunch. HD can get away with it because the front cylinder gets better cooling so they push that cylinder to the limit to get the bike to pass with a factory calibration.
4) Looking at an A/F ratio on a Dyno pull is meaningless because it was done during wide open throttle. During WOT the O2 sensors are not even looked at and the A/F is based on a RICH set of "look up tables" only. Under WOT condition the A/F ratio should be in the 12's not 13's. Under part throttle 13's would be fine but not for under WOT conditions. That dotted line on the bottom of ALL dyno pull charts is the "allowable" maximum not the optimum A/F ratio.
What all this means is don't base you cruise A/F ratio on what you see at the bottom of a dyno pull. The dyno pull was done at WOT while in open loop mode. Therefore it is meaningless unless you ride all day at WOT. Why doesn't anyone ever look at that beautiful flat A/F line at the bottom of the Dyno pull sheet and say "13.5 a/f at WOT is lean. It should be in the 12's"? It seems like all they focus on is the Torque curve.
5) Pipes alone without an air cleaner will substantially increase your VE at PART throttle. The side by side comparison of a stock Air cleaner VS a Stage 1 air cleaner under WOT conditions will show a BIG difference in flow. BUT when used at 50% of throttle body opening, I would bet they are pretty close in the amount of CFM each can and will pass. It is not until a throttle body opening of 50% or more, does the stage 1 A/C really kick in. Therefore unless you ride all the time at butterfly opening of 50% or more I would bet (theory) that both air cleaners will pass about the same amount of air.
What does all this mean? I am not saying that from 0-50% of throttle the stock A/C does not restrict flow to some degree. I sure it does to *some* degree. What I am saying is that a Stage 1 A/C was really designed around WOT air flow. At PART throttle (cruise) the VE of the engine is almost the same regardless of which A/C you have on the bike but the pipes increase VE all the time. Therefore it is my belief that running "just pipes" at cruise speeds requires the same ECM calibration tune as having pipes AND an A/C.
So does any of the above really mean anything in the real world. Heck, I don't really know. The Fact remains there are thousands of guys & gals riding with no problems at all and they could not care less about any of the above.
With that said there is one statement I can always quot as FACT.... I have been known to overthink a topic. If I rode my bike as much as I tinkered with it, the tires would be bald!
So I guess it just boils down to each persons own comfort level.
