Seca owners; Fuel level vs what the gauge says. And MPG

So i'm wondering how the gauges work on your Seca's. I mean does the first segment equate out to about 100km then the next segment will be 50.

Or do you guys find that you get more on the first half of the tank vs the last half etc etc.

Also, how many miles or km do you guys get before hitting reserve.

 

On my '81 Seca 750, I set off on the usual 20 mile run in the country showing just one bar. I didn't make it home.
2 gallons will take it from showing 1 bar to showing 4.

The way to get the real figures would be to fill your bike completely, then, with a charger boosting the battery, (to simulate the charge of a running engine) slowly drain the tank and measure.

I did a trip using the throttle lock at 60MPH and got 46 MPG.
On a faster all highway run, I got 42MPG

 

My gauge has never ‘said’ anything, I must read it.

The specs on the Seca 750 fuel tank are 5.0 US gal total with 1.08 US gal in reserve.
I have found my gas gauge to mostly coincide with one segment on gauge per gallon.
I find it hard to judge the accuracy of segments displayed for gals 1-5, but I have found the - no segments displayed while on reserve with bright red warning light pestering me – to be about 1 gallon. I have totally run out of gas on a few occasions. I do that with most all my vehicles at some point if for no other reason than to test the limits of the gauge and my sanity.

I have dialed my aging petcock to reserve and left it there. The gas gauge and warning light are plenty of continual notification. The reserve switch is only a one-time notification. How many cars do you know that have a reserve gas switch? Also, because reserve is really just the bottom of the tank, if you rarely switch to reserve you could get a build-up of fuel contamination that gets flushed into carbs all at once the next time you switch to reserve.

 

I find that the first half or the tank goes slower then the last. The gauge will say half empty if open the cap the gas is just below the tunel. I will get well into the red of the gauge before the bike starts to stumble calling to be switched to reserve. I get about 225 km before swicthing to reserve on 550 Seca. The big question is how far can you go on reserve???

 

I haven't had a chance to run through a full tank with it running half decent. This week will tell the story tho i will be reporting what i'm getting as a go here.

As a note, i do have the sport fairing installed right now, so that may help a little with aerodynamics on the next couple tanks.

Here's hoping the week stays sunny

 

The 550 will need reserve when it hits the red zone; but then again I have NEVER put more than about 3 gallons in it and supposedly it's a 4.2 gal. tank.

It probably could be adjusted to be more accurate than pessimistic; and I strongly suspect each bike is different (my 550s are slightly different, one more "optimistic" than the other.)

I consider it to be more a form of entertainment than a precision instrument.

 

Well so far this tank i've gotten 250 km, and i haven't had the atari flashin at me yet.

I really think i'm gunna take the warning bulb out of it, i could see how that could be dangerous at night. Way too bright.

 

...or put some black tape over that *";~ing redlight, just leaving a sliver visible, I can get about 300k on a tank then gotta find a fuel shop real quick.

 

Tape just looks bad tho lol, i'd rather take the bulb out when i have the fairing off next.

On a plus, i got 300km to reserve this past tank. It was kinda funny, it started bogging so i switched over to reserve, and not 5 seconds later my low fuel warning went off, right at 300 km lol i chuckled to myself.

After i fill up tomorrow i can report back with the mpg or L/100km and find out how much i have in reserve and calculate how far i can go on reserve before runnin dry.

 

So i got 313km on 15.2L of gas, that's 4.85 l/100km or 48.5 mpg. Not too shabby!

BUT!

There's always a but lol...

I went for the first longish trip on the 401 yesterday (our version of the US interstate for those who don't know) And lemme tell ya, doing 120-130km/h sucks the gas back lol i got maybe 130-140 km off the first half of my tank. I got 200 when i was babying it to work last tank.

So looks like i get sub 40 mpg when i'm really opening her up and not caring about efficiency. But me likey the fact i can get 300km to reserve if i'm being leisurely.

I think that hour long running at 120km/h (5.5k rpm or somewhere around there) cleaned her out and loosened her up a little too after sitting for 3 years lol she seemed to run much more smoothly on the way home after that.

 

KrS14 – thanks for giving me a clue as to why my gas mileage was in the <30mpg range, while I read some getting >45mpg. I only ever measured highway mileage. I assumed highway mileage to always be the highest. (oh ya, now I remember – that’s why the Fed 55 mph limit)
I have not measured the mpg in years, but when I did measure, I was driving highway with the speed needle pegged at 85mph. (real speed was 90-100)
I can’t drive 55 !

(The MB SLR McLaren empties its 21gal tank in 19min when driven at 208 mph.)

http://www.youtube.com/watch?v=hwDEqLHwNwk

 

I broke my 85 mph speedo going over the Cajon pass, in third gear. I'm geting 33 mpg now at 75mph using 10% ethenol blend gas, and it is running way too rich for the highway. I got 43 mpg at 70 with 120 main jets going from Long Beach Cali-Vegas on real gas.

 

Thing with driving over 80km/h (50) is that the wind resistance goes through the roof. It's not a linear increase either, it's more logarithmic.

So the faster you go, the more throttle you need, the more gas is used. If i stay around 80 km/h for a whole tank and don't gas it when going through the gears, that's where i get my good efficiency. Not too fun tho lol.

 

Oh this is true a well, i think they're stickin ethanol in all the reg gas up here too. I was using regular in my test.

I should throw a few tanks of the good stuff in and see how it affects it. But it's $1.16/L or so for the good stuff lol that's why i tend to not get it when the price is dumb (When isn't it).

 

The speed limit on the local turnpike is 75 mph (thats about 115kmph) and mostly only big rigs stay below it. Its 90 miles to the nearest metropolitan area when I leave this town. Fuel economy is somewhere behind not getting run over to me. I had a windshield that I adapted from a HD glide, but I trimed it and changed the angle of it recently so it would have greater fuel econlmy and handle cross winds better (not act like a sail). The later (handling) did improve but fuel econmy did not. I suppose the frontal area remains the same, the largest obsticle is my 6'3" profile sitting on the bike. when I did my Long Beach to vegas run I had seca bars with no windshield, now I have maxim knock offs and it makes a difference.

By the way, the lower bars are more comfortable to me after about an hour at speed, but the higher bars are way more comfortable around town.

 

im using premium and averaging over 60 mostly riding like an idiot on the highway to work and back

 

Well me being over 300 pounds, plus the extra hundred or so pounds difference from the 550 to the 750, i'll never see 60 mpg lol.

@Padre: I'm 6'3" as well, so i feel your pain. Gunna be hard to find a windshield that will work for me sitting up so high.. and not look like a crazy HD shield. I'm finding it uncomfortable after 30 mins or so, crouching down to get behind the fairing.