I was wondering if anybody else was experiencing this phenomenon and if so, does anybody know what the cause of it is?

If i ride my bike (stock 99 F4) almost everyday for commuting purposes, i normally get about 50 - 52 mpg. However, if i ride it only every so often, for commuting purposes as well, let's say once or twice a week, by the time i have to fill up, I calculate about 40 mpg.

When i first noticed this, I thought that i might be leaking gas, but i haven't been able to find any indications of a leak (smell, liquid, etc.)

Has anybody else noticed this? Any ideas why this may be? I don't ride the bike any harder when experiencing 40 mpg as compared to the way i ride when i average 50 mpg.

 

possibly just the gas vaporizing from the heat while it sits around?

 

I'd blame the gas your buying.

 

kdub627- that's what i thought at first, but the gas cap is a pretty tight fit and there is no gas smell. I figured that if it was seeping out of the gas cap that i'd be able to smell it.

Nauree- I wouldn't think it's the gas that i buy because I buy the same gas almost all the time. If it were the gas, i would think that i'd get the same low mpg or high mpg based on the brand of gas i get. I have found that there's no correlation. ( I normally fill up at Costco, but will occasionally fill up at Shell or Chevron. I have seen no difference in mpg based on where i buy the gas.) The only correlation i've been able to observe is more frequent riding translates to higher mpg.

It's not a big deal to find out what going on, it just really stumps me and picks at my curiosity.

 

Dont know where you live but heat does have an effect on fuel. Depends on what time you fuel up and when you are riding. Even though the tank cap is tight there are vent hoses that will allow vapors out. Fuel expands under heat, hence dont top off when hot because fuel will not have anywhere to expand in the tank except out the overflow.

 

Liquids do not expand nor compress. They vaporize.

 

sounds like you just need to ride more

 

Riding more...win-win situation! I have been riding more frequently latey-Weekend rides whenever i find the time and now i try to use my bike to commute atleast 2-4 days a week if not the whole week. Sometimes i just get lazy though to gear up for work if i'm running a little late or if i have errands to do at lunch or right after work and i need the cargo capabilities.

in any case, i was thinking about upgrading to an 04 rr sometime in the near future, but it looks like people are getting mid to high 30's for mpg with them. I think that may keep me on my 50 mpg F4. One of the big points i use to justify having a bike is saving $. I lose that justification if i'm only making a couple mpg's more than my car!

 

wow I didnt realize the rr got such crappy mileage, mine gets a solid 50mpg, my car gets around 40-42mpg.....couldnt imagine having a bike that gets worst than my car...