Rejetting will likely be the next thing I do to my bike, if I don't go with the heated jacket first (just ordered gloves).

Since there are so many factors in rejetting, I was wondering how much it mattered which season, or what the weather is like, when this work is done. I am in CA and ride 12 months out of the year to commute to work. It is hot in the summer (90's - low 100's) and moderately cold in the winter (30's-50's).

I don't know if any of this matters, but then again.... that is my question.

From what I believe, the temperature has got apart to play in it as the density of the air and how much gets into the engine is related on the air temp, I THINK the hotter it is, the denser the air is, colder the other way round.

You could rejet on a day that is an avg temp over the whole year, this will give a bike with the best power at the mid temps (as this is what you would tune for) or, you could tune (shimming the needles) when the temps get hotter and colder, this will gove you the most power for that temp range, but requires shimming more often.

Note, take my advise with a grain of salt, this is what I believe and I am new to this, so I could be wrong, wait for the others to advise.

Thanks.

Cold air is denser, but I know what you meant ;)

NP :)

Well I had a 50/50 chance of getting it right, I guess I should have looked it up, just couldn't be bothered :p

It does make a difference. I am running one jet richer right now for the colder days. When the temperature drops below 55 or so there is a noticeable difference in power. On really warm days there is an obvious lack of power...

Once spring time comes around I aim on stepping back down one jet size, and then back up next fall :)

I had put a second washer on mine when the temperature was in the 50s, and when I rode at 36* it was still running great... we'll see how it does when it's warmer in the spring, but so far it seems to be just about perfect for me.

Does temp matter much for FI bikes?
I assume the computer makes all the adjustments.

Does temp matter much for FI bikes?
I assume the computer makes all the adjustments.

Are you talking about our bikes? You know ours aren't FI.

FI bikes have temp sensors which relay that info back to the ECU.

No, I know we don't have FI..... I was just thinking about a 650r at some point and like the idea of not needing to tweak it all the time. Of course there are those power-commander thingies for FI bikes, but that is totally different.

Yes, FI will automatically adjust.

Not adjust as well as you can, though. Increasing the fuel map is a lot easier/faster than a jet though... not that you really need to do it anyway.