Poor Fuel Mileage

Just read thread about 15 miles per gallon. I have the same problem. The only mods I did was take out baffle throttle stop and grey wire. It ran great, but it was a little lean, and got 26 or better. I did all the other free mods, jetted, fuel screw, A.I.S. removal kit, cut out air box. Now it gets less than 15 miles per gallon. Fuel screw doesn't seem to do much either way I turn it. I took fuel screw out twice to make sure the O Ring was in place. Runs like a raped ape. It still seems a little lean in mid-range. Lowered float height, still gets poor gas mileage. Do you have any suggestions? Any help would be appreciated.


You should be getting 25 mpg under the hardest riding conditions with those mods. :naughty: What jetting are you using? A very high idle will cause loss in fuel economy. :naughty:

i feel your pain i have been messing with float heghts also i think i will bag jd kit and try stock yzf needle and jetting or maybe even go back to stock stuff,i hace emailed jd and got quick responses but not much info

My idle doesn't seem to be too high. For jetting; 168 Main, JD Blue #3, 48 Pilot, 40 Leak, 68 starter jet, 1.5 turns out on pilot, temp is 50-60 degrees, elevation is 2000-4000 feet, trails are tight.

-Shorty87, 05 WR 450

Hey guys, I'm REALLY sorry about double posting, but I need to know any info you have to help me! Please, please!!! Thanks a lot.


I run pretty close to the same jetting. For trail riding I get ~24 mpg, and racing I get ~21 mpg (depending on the course). Here are the four things that I can think of that might be causing your problem:

1. Your not measuring your mpg correctly. I won't go there.

2. You are a "revver" and not a "lugger". I'm a lugger, and imagine my mpg would be much lower if I was always a gear lower and higher in the rpm's.

3. Where you are riding. You mentioned tight trails in your post above. If you are riding in 1st and 2nd gear all the time, your mpg is going to be lower.

4. Fuel leak. I've seen this quite a few times on four strokes (mostly guys that came from a two stroke, and thought all bikes were supposed to leak fuel). Make sure your drain tube from the float bowl doesn't leak when the bike is running.

I'm assuming there isn't any gas in your oil? Can't think of anything else, hope that helps.

Okay, thanks for all your information, guys. You've been a big help.

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