fuel milage went down

Hey all, looking for a few ideas on what might be my fuel mileage problem. 2007 WR450 and was going onto reserve at 90-95 kilometers last year. Upon using the bike after the winter I am now going onto reserve around 65 kilometers. Carb and tank were drained prior to winter and new gas put in for riding. I didn't change or modify anything. Bike is running good. Air filter is clean. It starts easy cold or hot. I am puzzled. Thanks in advance for any thoughts on this.

Do you have a filter on your fuel hose? Maybe some dirt is holding your floats open a slight bit allowing more fuel to come out of the vent hoses. I've even had the float needle develop a slight groove in it which allowed to much fuel into the bowl, which would do just that. Or maybe your just alot faster this year!!! Maniac

Thanks for the reply. no fuel filter on the hose and haven't noticed any fuel leaking out the vent hoses. I am thinking about pulling the petcock and checking for a filter or screen that may have some kind of blockage. This is a hard one to figure out. Unfortunately I don't think I am any faster this year.

I see you're in Canada, what are the odds that your area switched from pure gas to ethanol laden gas? That can have a big effect on mileage.

Getting premium fuel from the same station for the last couple years now. Haven't noticed anything regarding fuel change at the pumps. But I will check when I get some more gas this week. Thanks.

I see you're in Canada, what are the odds that your area switched from pure gas to ethanol laden gas? That can have a big effect on mileage.

Maximum allowable ethanol content in Canada is 10%. Has been that way for a while..can't see that accounting for a 30% reduction in gas mileage.

It's generally 1:1, 10% ethanol equals 10% mileage loss.

What I was thinking if Canada went with 20% (Becoming increasingly common in the US.) he's jetted it and is on the rich side then I could easily see the loss he's talking about. At least that was my train of thought!

But if it's been that way for awhile and the max is 10% then odds are that's not it unless there's something screwy at the station. Are you getting fuel from different locations?

Always getting fuel at the same station. I haven't changed anything with regards to the jetting since I got it dialed in a couple years ago. I did get the valves adjusted about a month ago at the dealer. They were a little tight.

What about the odometer being switched from kilometers/miles:excuseme:

odometer is still reading km's. Going to take it out today and run the bike right out of fuel and see what the odometer reading is then. I am hoping it is something wrong with the petcock.

Is there a screen of filter of sorts on the end of the petcock inside the tank?

It's generally 1:1, 10% ethanol equals 10% mileage loss

Don't mean to change the subject of this thread....but if the relationship of amount of ethanol to amount of mileage reduction were 1:1 as stated above...then an engine running on 100% ethanol (a legitimate fossil fuel) would then get 0 miles/kilometers per gallon.

It is my understanding that E85 fuel (85% ethanol 15% gasoline) can result in up to a 30% mileage reduction. http://en.wikipedia.org/wiki/E85

Interestingly..this is the amount of mileage reduction that Panda39 has reported.

Perhaps he is unknowingly filling up with E85?

I am using premium gas at Petrocan. I don't think they have changed their mix since last season.

Yeah...I figured the E85 idea was a long shot but thought I'd just throw it out there.

Once you fugure this thing out please post your findings. I'm really curious to know whats up.

Don't mean to change the subject of this thread....but if the relationship of amount of ethanol to amount of mileage reduction were 1:1 as stated above...then an engine running on 100% ethanol (a legitimate fossil fuel) would then get 0 miles/kilometers per gallon.

It is my understanding that E85 fuel (85% ethanol 15% gasoline) can result in up to a 30% mileage reduction. http://en.wikipedia.org/wiki/E85

Interestingly..this is the amount of mileage reduction that Panda39 has reported.

Perhaps he is unknowingly filling up with E85?

Please note operative word......Generally. Per my experience and per General Motors R&D data with common blends with a non flex fuel car it's pretty close to 1:1. Common being up to 20%. E85 is specifically for flex fuel vehicles so in a regular non calibrated situation the numbers will be different.

My 2010 flex fuel Impala actually loses only about .2 MPG on E85, I've got to admit that impressed me.

Back to the program.

Actually something I'm doing with my WR is running it on the road to establish a MPG number so that if something like this comes up I can evaluate it subjectively. Maybe an on road baseline could help with this?

Also if they screwed up your valve clearance that could definitely be the culprit. It might seem to run fine but a little can make a big difference.

I finally figured out my problem. When cleaning the air filter today I discovered the screen in the frame that the filter mounts on has become about 25%+ clogged with oil over the last couple years. The funny thing is that the oil on the screen was clear and didn't appear at first to be clogging it. Brushed it clean using gas and blew it out. Mileage back to normal, all is happy again.

Oh yeah, I also discovered that my tank goes to reserve with 2 litres fuel in the tank not 1.1 like the manual says. 85-90km then switch to reserve with 25% of my fuel still in the tank. bonus

Interesting! Glad to know you finally figured it out. Maniac

anyone know the optimum jet sizes????

I am looking to calibrate my milage on my WR450 '07. It has the stock pipe but without all the smog gear. I put in the recomended jet set etc when I did all that a few years ago (have the sizes written down) but my milage has always seemed low compared to others I ride with! I usually only get about 45miles before going reserve (stock 2.5 or .8 tank). I think once I did about 6o mile and ran out. anyone know the optimum jet sizes??

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