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poor gas mileage

8K views 25 replies 19 participants last post by  JRWalker 
#1 ·
my 03 vee gets about 150 miles per tank. I'm assuming thats NOT normal. Any ideas why? or what to check to fix it ?? I'm not that concerned about filling up more frequently but a longer range would be nice!
 
#2 ·
It would be more useful to keep track of miles travelled per gallon consumed over several tanks. I'm not sure range is particularly meaningful, given that no one can know how far you run it down or how much you fill it (which varies each time -- hence the need to calculate over several tanks).
 
#16 ·
Ditto. If you're only putting in 3 gallons for 150 miles, you're refueling too early because your fuel gauge isn't indicating properly. I rode a summer and a half with no fuel gauge and usually started looking for a fuel stop at about 200 miles. Only ran out once, and that was my own dumb fault (had 240 miles on it). Didn't leave me stranded.... Coasted about 1/2 mile to the next off-ramp, blew the stop sign at the top of the hill, hung a right, coasted down the approach, hit the starter at the entrance to the truck stop, goosed it up through second gear (it's a long entrance drive) and coasted the rest of the way to the pumps. :) Got lucky... If it had happened another 100 yards down the freeway, I never would have made the off-ramp.
 
#7 ·
I've been averaging around 33mpg. I do have several mods including K&N filter, secondaries removed, two brothers exhaust and PCIII. I attribute my mileage to my riding style. I generally ride in lowest possible gear to take advantage of engine braking and maximum torque when needed (5000 to 7000 rpm). I used to get better mileage when I had just purchased the bike and rode it like a cruiser and shifted into a higher gear as soon as possible. I found that the bike maintained a better MPG average but suffered performance wise when riding this way(3000-4000 rpm). I only ride in the 4000 range when on the highway for long distance travel. FWIW
 
#9 ·
I was only getting about 150 per tank also. About 35 mpg. The mileage was bad enough but I am used to going over 240 per tank on the Beemer and for a back road bike 150 per tank is a little low for me. I have the aftermarket exhaust, K&N, everything tuned properly. Changing the fuel maps in the Power Commander fixed it! Mine was too lean which actually hurt mileage. Way more power now and I am at 40-41 mpg. That helps the miles per tank a lot! BTW, I am running the 16/43 sprockets.
 
#10 ·
realshelby, I would be very interested in your map for the PCIII. My vee is getting about 32 or 33 mpg on every tank. I am a fairly aggressive rider but I would like to squeeze a little more mpg's out of the bike.
 
#11 ·
Been getting 40+ all summer - then made a mad dash from SD to WA on I90. Dropped to around 35. Then on hwy 14 along the Columbia, it dropped to 30. Fast driving on the slab hurt, but that damn head wind was brutal! Riding two up with gear - around 1100lbs.

Mechanically stock bike except for the cans. Keep the Anakee's inflated to 42.
 
#12 · (Edited)
Does the exhaust smell rich?

If the exhaust smells rich, then the rear intake cam is off by one tooth. Also, your mileage would drop from 40 mpg average to 30 mpg average. Drastically in other words.

Did that, been there, unfortunately. There is a way to tell decisively. After accessing the rear cylinder head:

Turn the crankshaft to align the "F|T" line on the generator rotor to the index mark of valve timing inspection hole & the exhaust cam lobes should be
at the 3 O'clock and the intake cam lobes should be at 12 O'clock position exactly from the right side of the bike.

If the intake cam lobe is instead at the 11 O'clock or 1 O'clock position then it is off by a tooth, correct by removing the intake cam and setting it to the 10 O'clock position exactly.

I can even show you a picture of this on the internet. Go to this web page:

Engine valves adjustment: Can you help me understand the procedure?

Scroll down to the bottom most picture. Notice that the Exhaust cam is exactly at the 3 o'clock position? Notice that the intake cam is at the 1 o'clock position? The intake cam is off by one tooth. It should be at the 12 O'clock position and not the 1 O'clock position.


Suzikawa

DL1000K2 (52K miles) and running smooth and strong.
 
#13 ·
If the exhaust smells rich, then the rear intake cam is off by one tooth. Also, your mileage would drop from 40 mpg average to 30 mpg average.
In the interest of scientific rigor, I feel compelled to point out that

B = A

does not imply that

A = B.

In other words, that your particular problem resulted in a particular symptom does not mean that everyone who experiences that symptom has your particular problem. :)
 
#20 ·
I calculated my mileage for my latest tank of fuel - 20 l for 240 km, or about 29 mpg. That was an unusual tank, though, consisting of a lot of low speed, stop and go dinking around combined with several higher speed highway runs, at least one of them against a strong headwind, all of it 2-up. I don't think I've ever seen much better than 40 mpg - maybe 45 mpg if "babying" it (by my standards).

I did just recently do a valve adjustment, but I don't think my intake cams are off (wouldn't having the front intake cam off by a tooth affect the bike the same way as the rear?). I don't see the need for looking at the cam lobes however - there are the alignment marks on the cam gears which indicate pretty clearly if you're on the right spot or not. Tricky to see on the rear exhaust, particularly - I found laying a small straight edge of some sort (like one of the stiffer feeler gauges) across the cutout in the head made it pretty clear to see, though.
 
#22 ·
I don't see the need for looking at the cam lobes however - there are the alignment marks on the cam gears which indicate pretty clearly if you're on the right spot or not. Tricky to see on the rear exhaust, particularly
It's important to check not only the cam gears but also the lines in the cams themselves. With the spring loaded split gears, the gear marks can be correct but the cam off by 1 tooth.

I had this happen to me on my 1st shot at reinstalling the rear exhaust cam. Rolled the engine through by hand twice to double check and it was definitely off. I removed and carefully reinstalled it and then all the marks & lines aligned as they should on all cams.

I just started using the Commander and tried a couple different maps, the last one I leaned out a bit myself. I'm still not breaking into the low 40s' mpg range yet, hmm. I have not had a "good" easy freeway run yet without head winds etc. so that may not be helping. I'm running 17:43 gearing. I generally ride with a pretty light throttle hand.

The bike is all stock other than the PC. I've sync'd the secondaries and primaries. I'm running a speedo healer calibrated from my GPS so the mileage count should be quite accurate.

I started with the "Jett" map and was in the low 30s with soot in the pipes, way too rich for my bike. The map I'm currently running is "custom dyno tuned" which I manually leaned out in a few areas after reviewing several other maps. That got me into the high 30s. Seems like I'm still not quite there yet.

For those routinely getting in the low to mid 40's what maps are you running? And have your speedo/odo been adjusted? or do you use GPS? If the speedo reading is fast it will record more miles than actual giving better mileage figures.
 
#25 ·
Wow, I must have a super Wee, mine has got 58 to 63 mpg over the last 4 tanks, and that is in the mountains, not running it all that easy.
its only been getting better and better as it breaks in, about 1300 miles on the bike so far.
~John
 
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