View Full Version : Fuel Temperature

07-02-2007, 03:31 PM
I noticed recently that my bike always runs best in the morning and worst on the way home, after it has been out in the sun all day. This was never a problem before, but as I mentioned in other posts, my scoot is starting to suffer from old age. My running sluggish problem has improved quite a bit since I was able to get the injector head cleaner by spraying carb cleaner into the cylinder, but it still runs best in the morning.

Since the Ditech runs best when fully warmed up, I thought this seemed odd that it ran like crap at the end of a warm day. Then I was reading something about how F1 restricts the fuel temperature and doesn't allow any fuel cooling devices. I think it said that cooler fuel is heavier and therefore burns more efficiently. So when my fuel has been in the scoot in the sun being heated all day, could this make it harder for it to get through the injector?

If so, I guess what follows is a fuel cooling device, like one of those cooler inserts that you put in the freezer. I wish I could find a shady spot to park in at work, but there are none.

07-04-2007, 08:52 PM

33 views and no thoughts?

07-04-2007, 09:04 PM
Lighten up, TImmY! There are alot of variables to deal with, such as elevation, humidity, microclimates, ( I ride through atleast 3 micro's riding to work, and its less than 10 miles!), fuel type, mods, miles/age of scoot, etc, etc. I feel the same changes sometimes, but, then my theory goes to hell when it performs like a demon at 90degrees vs morning temp of 55f. Crazy.

07-04-2007, 09:43 PM
I agree with 06Spidey, TiminIndy, there are a lot of variables influencing bike's behaviour. In my thought the difference mostly come from two things, temp of the engine and temp of the variator area. The engine runs better when it reaches the proper temp, but the heat soften the contra spring and belt so the bike accelerates slower. So in hot days you have a better topspeed but a slower accel. The thing is to find a system to let the transmission breath better.

07-08-2007, 04:36 AM

I find that my 06 also likes the morning better than the afternoons during the summer. I think it has more to do with the air temps/ humidity than the fuel temp. You will find a much larger difference in the air density based on temperature while the fuel will stay the same through a wide range. When we run our snowmobiles, we are constantly jetting differently to keep up with changing temps and weather conditions. The colder air is more dense and contains more oxygen... therefore leaning out your mixture. I doubt the ditech's temp sensor is advanced enough to adjust the mixture much in our scoots...

My .02