miles per tank load

[oldyam80sg]

I don't even want to post what i get.If i get close to 80 that's pushing my luck.Dynojet kit in the carbs,stop and go traffic,some lights on the way to work and if i hit an open stretch of road and no cops i will push it.I don't think i ever got good mileage and my attitude is no matter what the price of fuel is,the bike wont run on anything else but gas so be it.Almost at 70 miles and have not switched to reserve and no red light-yet!

[Gyrogearloose]

Well, I guess I'm lucky, but I do keep'er tuned up: keep an eye on my plugs, have shimmed the valves and put on a new cam chain this last year. Yah, that's 40-43 mpg consistantly, if I don't get the adrenalin bug, and try to stretch my face. Ha. Only mod I know of on my 80SG is a 4to 1 exhaust (brand name ukn). I try not to pass a gas station after 120 miles.

[Craigaboy]

40 mpg @ 60-70mph through a mountain pass - with a little throttle here and there. 128 miles to fuel light.

[Mendizale]

I've been averaging about 30 miles per gallon for the last several tanks.

I'll climb on the back of this forum to ask: how big is my tank, anyway? I have a 1979 XS11 Special that seems to take just over 2 gallons at each fill-up, which seems small. Also, how much is in reserve when the light goes on?

Thanks,

Mendizale

[tcoop]

The special's gas tank is 15 Liters. I don't know the conversion rate but I think that about 4.3 to 4.6 gallons. Is your low fuel indicator coming on after 2 gallons?

[CatatonicBug]

15 L = 3.96258 gal(US Liq)

If you're only getting 2 gal when your light comes on, something's not quite right. How high do you fill your tank? Do you watch the fuel level come all the way up to the fill hole? Remember that you can't fill bikes like you can with a cage and just stick the pump into the fill hole.

My light comes on after about 80-90 miles (depending on how I twisted the throttle for those miles), and I have to switch to reserve within 1-2 miles after that. I can then get about another 10-15 miles out of it. Maybe more, but I've never been brave enough to drain it completely.

The fuel sensors in the Special tanks have no moving parts (no float or micro-switch). It's a thermistor that, when submerged in fuel, stays cool enough to not turn on the light. Once it is exposed, it heats up enough (with electrical resistance) to trip the circuit and light up the warning light.

[Bonz]

My 80 SG for most of it's life with me, had the low fuel light coming on at 107-108 miles like clockwork, then reserve at 115-117 miles, at which point I'd have .6-.7 gallons left based on carefully filling the tank to the same level, at the same gas pump, parked in the same spot repeatedly over many, many tanks of gas.

I did the Final Drive swap about 500 miles ago, and now the low fuel light comes on about 120-121 miles, then reserve at about 131 miles.

I'm really pleased after the swap with the extra mpg the lower rpm gives me, as I run up and down the interstate for a 34 mile round trip commute back and forth to work. The 500 rpm reduction at 75 mph has the bike feeling much more in its element, as well as giving a nicer spread between all the gears.

[tcoop]

15 L = 3.96258 gal(US Liq)

Wow. I didn't realise how small the special tank is. My wifes XJ750's tank is bigger.I was thinking of putting the special tank on but now I think I'll stick with the standard tank (at least for long rides).

[Bonz]

Yeah, it's a bummer to have a relatively small tank at 4 gallons on a bike, especially the Special with the improved suspension relative to the Standard which makes it a really good bike for the long hauls in terms of comfort.

I have mine set up with a Plexifairing 3 windscreen, which is a great addition to a Special or Standard if you want protection on longer rides and higher speeds, and I guess the final drive swap is the equivalent to adding 1/3 of a gallon to the tank capacity because of the increase in mpg, all else being equal.

I've owned a number of bikes, with the smallest tank being on my 80 SG at 4 gallons, the largest was 7.7 gallons on my Honda ST 1300, with 5 gallons each for the '97 Bandit 1200s and '01 ZRX 1200, and then my '03 VStrom 1000 at 5.8 gallons.

The Honda could inhale 300 miles easy in one sitting if you could sit there that long.

My personal preference is a tank around the 5.8 gallon capacity. That'll getcha' at least 200 miles to a tank with some room to spare.

[cywelchjr]

I'm not aware of any significant differences in suspension between the standard and special. They both run the same shocks on the rear, the forks are different, but 80+ both run air shocks. Both have the same wimpy 37mm forks. I think the slightly larger 17" rear on the standard might if anything smooth out the ride ever so slightly on the standard, and XJ air shocks smooths out the ride a LOT on either model and are dead easy to install and allow almost infinite adjustment of the rear suspension sag. I'd like to pick up a special for an around town bike, one to fix up to showroom quality, and another standard to setup as a hack. Three ought to be a good start anyways.

[Bonz]

Hey Cy,

Here's a snippet from one of the period magazine tests found on the forum, talking about suspension differences. January 1979 Cycle Magazine.

Maybe by 1980 the Standard had the same shocks in the rear and the air fork up front (but without the leading axle found on the Special), but at least through 1979 (first year for the Special) the Special had better components.

Here it is:

"This characteristic was noted on last year's Eleven, and while it is certainly no worse on the '79 Special, it seems more noticeable because the rest of the bike is substantially more at home humping through the hills than the '78 Eleven was (and the '79 Standard Eleven is). With the Special, Yamaha has followed Suzuki's lead and has fitted an air front fork (an update on last year's adjustable fork spring preload feature) and adjustable damper rear shock absorbers. The front fork itself is similar to the unit fitted to last year's (and this year's) 750 Special. It has sturdy 37mm fork pipes, 175mm of gently damped travel, uses SAE 10W20 oil and dual-rate springs (the second rate takes over after 4.3 in.- 110mm - of travel). The fork is completely different from that used on the Standard Eleven in every particular except travel. It has a forward-mount axle, 750 Special-type single-piston brake calipers which use an insert fitted to a boss on the slider to locate the upper portions of the bias-beveled brake pads (this is done, we're told, to better control brake squeal), and is designed to function with additional springing provided by compressed air. Standard recommended pressure is 5.7 psi; maximum is 36. Our test model was delivered with 13 psi in each leg (measured with the front wheel on the ground) and experimentation revealed that, for all practical considerations, 13 is just about right.

In keeping with the SFs trick-o front fork there is a pair of adjustable damping shocks attempting - with some success - to keep things under control at the other end. Thumb wheels located beneath the upper shock mounting bosses have four click-stops, numbered one through four. The higher you dial the stiffer the damping becomes. For all-around riding we set the spring preload in the third of five notches, and the damper adjustment on click number two.

We were a bit confused by all this, to tell the truth. Why would Yamaha fit these technically advanced suspension components to a motorcycle whose layout was not really conducive to the kind of riding which would most benefit from their superior action? There are several answers. The first has to do with value, real or implied. Last year's Eleven cost $2989 at its introduction: the '79 Special will whack your wallet to the tune of $3699 - a breathtaking $710 differential. The forward-axle air front fork and the superior rear shocks are the only components which significantly improve the function of the Eleven. Without them the price hike would be more difficult to swallow.

Second, the Special Eleven is a new model, and factories like to apply new developments to new models-especially if those new models are top-of-the-line. Third, the suspension components serve to distinguish the Special from this year's standard Eleven, which at $3449 is $250 cheaper. Fourth - and far from last in importance - the new parts work better."



I replaced my worn out stock rear shocks with Showa shocks off of a Shadow 1100, and despite the Showa's not having any damping adjustment, they made a great improvement in ride quality and handling compared to the tired stock shocks that were finally giving up the ghost as noted by the thin dust film that would accumulate on the shock body. Just didn't control the ups and downs as well anymore. The Showa's rock!

[bikerphil]

FYI-

The Standard uses KYB forks and the Special uses Showa forks. The Showa's have 4 teflon slider bushes internally as to the KYB's 2 bush setup. Less stiction on the 4 bush setup, JMHO.

Both my Standard and Special average about 40MPG with the 850FD mod. Special 120 miles till reserve, Standard (running only left petcock) 155 till reserve.

[Mendizale]

Is your low fuel indicator coming on after 2 gallons?

The bike sat in its own juices for five years, and I've only cycled through about 8 tanks of gas in the past few weeks. Each tank is an improvement over the last. This time around, the light came on, I stopped almost immediately to fill it, and the tank took 3.10 gallons. Sounds like there should be about .5 gallons to spare, which would make my tank a 3.6. Obviously that's not the case, so I'm assuming the .5 gallon reserve is approximate, right?

[SFSPECBIKER79]

79 spec

i was getting 135 mile before the reserve light came on,40 odd miles to gallon. then i had a carb float needle leak, i rebuilt the carbs useing kits from georgefix now i'm getting 33 miles per gallon. hitting the pump at 100 miles now, have changed tanks and no reserve light. mileage suxs now and dont know why rebuilding carbs would have negative effect on mileage. and they are no changes in performance and plugs are tan.

[Bonz]

Mendizale,

What you reported in terms of the light coming on, and immediately filling up with 3.1 gallons is spot on where you should be with the Special's 4 gallon tank.

My low fuel light comes on, I have about another 10-12 miles until reserve, and when I fill up as soon as it hits reserve (literally pulling into a station as it starts to sputter), I put in .6-.7 gallons. At an average (before my final drive swap) of 36 mpg, that fits perfectly with a 4 gallon tank.

So, in a nutshell, when the light comes on there is about .9 gallons left based on my experience as well, and when reserve is needed, .6-.7 gallons are left in the hold.

Only caveat I'd share, is can every bit of fuel in the tank be accessed once reserve is switched to? Based on taking my petcocks out and cleaning them, looking at the tank shape and position of the petcocks internally along with the fuel screens, I'd say you can get most of what's in there out when on reserve.

So, .5 gallons like you say probably would be a safe number to use for what's useable in the tank once you hit reserve.