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Fuel Consumption levels weirdness. Gauge/Monitoring?

1711 Views 10 Replies 9 Participants Last post by  v8eyedoc
Hi all.

I recently put my scooter into the TokyoMoto shop in SF for an oil change (also replaced my rear plate light, good catch). Was during work and I dont get much spare time to myself (family life) to do anything (or figure out where to recycle the oil etc.) so the money was well spent from my perspective (caveat caveat etc).

Before oil change = fuel consumption would be pretty quick to notice a change and responsive in how it portrayed fuel consumption. We are talking average of course, it does not provide instantaneous. Even though, it was pretty quick to update, and would climb pretty quickly once the motor and everything was up to speed and my cruise on the highways was settled down to an average 65-75 average depending on traffic (usually lots, its the Bay Area after all).

So, quick to update, and quick to climb pretty high to around 59 or so (after fitting the 20g Dr. pulley sliders) with brief sojourns to 60. Where it drops is in idling (drops steadily there) and in town use, or slow speed use.

Even so, the gauge would climb up fairly quickly, even towards the end of a tank of petrol - i.e. the average would still come up a bit.

After oil change - first thing I notice is that the average consumption is now at 53.9 or so, and heading home, dives a bit further in traffic to get to the bridge home and then on the highway, only slowly climbs up to 55 or so now.

Refilling the tank and resetting the meter resulted in a slow and unconvincing update, which is pretty much how things are now. I realize things change - ambient temperatures, tyre pressures, etc. variable after variable. But I was CONSISTENTLY getting similar readings before.

Now, what is consistent is that it is slow to update, and slower to climb back up to 59 - takes nearly a full tank of fuel, whereas before, it was eager to display that on the basis of a good steady run. NOW, no matter how I drive, it just doesnt seem to make much of an impact. Almost like it is reluctant to climb, even with my best hyper miling techniques..

Anyone have any ideas!?!?!?
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I've found that fuel consumption is dependent on many variable, not the least of whaich are quantity and viscosity of the oil in the system. I use Rotella T6 in the IceBurg which is a 5W40 oil. If the sight glass is at the low line on the sight glass and I add oil until it reaches the upper line, I'll drop 2-3 mpg off my indicated mpg. It is also more noticeable while warming up, less so once warm. Really notice it in the winter months. Finally got around to changing my final drive oil this weekend at 21K :oops: . That, too, seems to have made a slight difference. If I use 10w40, I lose a few more mpg when cold.

I also notice that if I fill up just before arriving home at night (park it with 10 miles on ODO2 and 68 or so mpg indicated), the next morning it'll drop to the mid 50's during warm up. The ambient temps are in the 70's. From that point on, due to the effect of having more miles a given tank, I'll be constantly nudging the indicated mpg higher (drops less during warmup and is a little higher when I park it). My final mpg for that tank will be around 62-63.

If I fill up on my way to work, and park it once I arrive with about 22-23 miles on ODO2 and 68 mpg indicated, when I head home in the evening, the indicated mpg will dip to the low 60's during the afternoon warmup. Ambient temps are now around 90. In this case I'll finish the tank with an indicated mpg around 64.

My calculated mpg in both cases is right around 65.

There have been a couple threads lately concerning Burgman mpg figures. From my experience, the 400 takes around 10 miles to reach what I term as the 'break even point' in the morning. This is the point at which my mpg returns to what it was when I started. In the afternoon, if I resist the urge to race the more congested traffic and drive like I do in the morning, the break even point is more like 5 miles. To the riders that wonder why their mpg isn't what others list, I suspect you make shorter trips. My work commute is 32 miles twice a day. I rarely ride otherwise so once I start my scooter, I'll be riding for about an hour each time in a mostly rural setting. Plenty of time to warm up and have 20-25 consistent miles before I park it. If my typical ride was less than 10 miles, I'd be hard pressed to reach 60 mpg indicated. If it was 5 miles, I'd expect 55 mpg. BTW, the shortest trip I typically make is to the nearest grocery store. It's 6 miles RT.

But back to the original post, depnding on the oil level indicated on the sight glass, and time of day, and viscosity rating, and miles on the current ODO... any indicated mpg between 60 to 65 would be completely normal. The best indicator, IMHO, would be to signup on and track your mpg consistently for a while. That'll give you a more complete picture and, after 10 or so tanks, a meaningful avg mpg.
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On any motorcycle the instant mpg figures are hardly accurate. Why not figure the actual mpg from usage over a tank or two, instead?
Because the mpg over a tank or two is hardly accurate. I've calculated 68 mpg for one tank and the next is 62-63. If accuracy is your goal, you'll need a larger sample.
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