Anyone know if

[naked-daytrader]

humidity affects the throttle response on a fuel injected bike? Yesterday the duke seemed a little lazy in 1st and 2nd gear, was hot and humid out (as you all probably know) could this affect a bikes performance?

[OreoGaborio]

yup, hot & humid means thin air.... thin air is less dense which means less air/fuel mixture is able to fit into the cylinders, which makes for less HP.

A cold dry day will have the opposite effect. Cold & Dry means the air is dense which means more air/fuel can get into the cylinders, making for more HP.

[naked-daytrader]

yup, hot & humid means thin air.... thin air is less dense which means less air/fuel mixture is able to fit into the cylinders, which makes for less HP.

A cold dry day will have the opposite effect. Cold & Dry means the air is dense which means more air/fuel can get into the cylinders, making for more HP.

I thought something to that effect but couldn't exactly remember. Thanks. I just picked the bike up yesterday with a new ECU and it seemed slower down low and wasn't sure if the weather was affecting it. The ECU was an upgraded performance one so that's why I was scratching my head over the sluggishness...Come to think of it, up in New Hampshire (where I picked the bike up) you could hardly breathe it was so damn hot. It felt like a jet engine blast up there. When I got closer to home the bike seemed to pep up a bit.

[OreoGaborio]

yeah, it wouldn't surprise me if it wakes up once this heat wave passes. Hopfully that's all that's wrong.

[RandyO]

my opinion is that the heat affects our new 10% ethanol fuel blend more than straight gasoline

I have always experienced sluggish running on hot days and ride in winter for the free horsepower you get, it's worse lately

my dealer told me they got a bulletin from Honda for small power equipment, generators/lawnmowers & stuff like that, if the item is going to sit unused for more than 5 days, drain the fuel completely from the system if it contains any ethanol , WTF

[OreoGaborio]

my opinion is that the heat affects our new 10% ethanol fuel blend more than straight gasoline

I don't really see how that would be the case. The way I see it, it's more a function of air density than type of fuel.

[ZX-12R]

Also, lots of fuel injected bikes have temperature sensors in the airbox. Depending on how the manufacturer decided to implement the system, the ECU can adjust fuel and timing to prevent detonation when it is hot out. When it's cold outside, the computer advances the timing and delivers extra fuel to take advantage of the denser air.

[OreoGaborio]

good point, forgot about that.

[RandyO]

I don't really see how that would be the case. The way I see it, it's more a function of air density than type of fuel.

just an observation over a thousand or more tanks of fuels in the past few years and a discussion with my mechanic that they are getting a lot more fuel related problems since the blend has become pretty much standard

[OreoGaborio]

Hmm, weird. Wonder why that is.

Not that I doubt you... I know heat & humidity affects all combustion engines & I know ethanol content can make for some weird symptoms in some engines.... I just don't know why temp & humidity would have more of an impact on an engine run on fuel w/ ethanol than a car w/ no ethanol.

Gonna have to ask TLRMan about that one, maybe he knows.... Hey Maaahk, wut tha fahk?