MPG & What octane gas do you use? - Take 2

[KA1J]

Regarding MPG, the earlier poll regarding tire pressures & mileage leaves a lot of questions unasked. Some of the unasked questions might could be differences in carburetion in that the BS34 had several different versions in the 1100 engines. Perhaps the YICS might translate into better MPG as well as the supposed lower emissions. electrical differences from zero ohm mods to plug caps & dynacoils, different advance systems, maybe even the mod to bring voltage directly from the battery to the coils via a relay. Heck, proper syncing, different oil being used, terrain is surely a part. & much more.

One variable thing we all can easily change is the octane rating we use and I wonder if that may have a bearing on MPG. Years ago I thought the higher octane rating meant it represented a more powerful gasoline. I don't know how many gallons of "high test" I wasted in the lawn mower because of that. - I've read it mentioned that higher octane gasoline may also have the added benefit of less ethanol added. May be true but nobody I've found yet who is "official" has replied to that in the affirmative.

If I put 93 octane in my XJ11 it doesn't smell like its running rich and if I put 87 octane in I don't hear it knock. I earlier decided to use 89 octane and leave it in-between the available 87 & 93 octane & pay a bit more than the cheapest gas but maybe cover all bases. - Since I am in Boston 4 times a month, whenever I drive the car I bring 5.5 gal gas cans with me & fill each with 3 gal of 93 octane and 2.5 gal of 87 octane which works out to 89.7 octane but works out to be cheaper than buying 89 octane (Yeah, I'm cheap). At home I never fill up from the local station & fill up from the tanks. Connecticut gas is 40 cents/gal more expensive than Boston Gas...

One of the things that has me curious is why I seem to be getting the MPG that I am; If I ride at 65-75 I am getting 41.7 MPG Today I decided to drive the same road but like a little old lady to see what MPG is possible and staying between 55 and 60 on the interstate I got 42.97 MPG (I'll round it up to say 43 MPG) Personally I'll take the 1.2 less MPG and the faster speed from now on But still, it has me curious. Perhaps using the higher octane makes a difference?

So, what is your Octane & your MPG?

[donebysunday]

City gas 87 w/ethanol, 23-25 mpg.. 20 miles out I buy the 93 non ethanol for an mpg. of 29-30. 40 mi. out 92 non ethanol gets me 38-40 mpg. all averages. Stock headers straight through dunstall reps, stock air box with K&N filter, main jets upped to 120, idle needles set 3 turns on 1&4 3.5 2&3. Pugs NGK BP6ES gapped at 30, near white nice and clean with the 92 octane. I did get better mpg. with the UNI pods and old 4-1 pipe/s, stock jetting.
I use the 92 from 40 mi. away now from my cans/jugs tilted so as to use them as sediment bowls. Wait till I'm almost out and drive 40 mi. to fill the car (it gets 3 mpg. better with this fuel) and fill 35 gallons of jugs to bring home for all gas powered engines.
This is on the LH the SH is still in the works but all stock.

[KA1J]

Nice you can get non ethanol gas! I've looked all over and it's not sold in CT, RI, or MA as far as I can tell. Ethanol has to reduce MPG. The gas I get does come from the city so I'm sure it's got all kind of EPA mandated chemicals in it & probably the max ethanol too.

I did replace the carbs with a dynojet kit in them with a totally stock carb rack for the XJ11. Replaced the throttle shaft seals on both carb racks. Don't think there's much if anything I can do to get better MPG. Going to see how the Dynojet rack does with the tires at 39 pounds in them.

It's good to hear how others are doing and what gas/tire pressures they're using.

[Rasputin]

All we have available to us in regular gas is the 87 with ethanol (10%) . I use it, have tuned to it and am mostly disgusted every spring when carbs need cleaning.
That said the tuning needed will return the mileage you want with the right carb tuning (or as best as you will get).
Still searching for the best fuel stabilizer for our northern winters and will be trying something new this year. Not yet certain if I will try mother yammys solution or an after market one but it will be new to me.

[donebysunday]

Seafoam was what I was using in the E-10, worked fine for keeping the fuel over winter with the tank almost filled to the top. Not to full though especially if your filling during a cold spell. Did that on an XS650 and my paint job which was very special had rivers of washed away paint when I lifted the cover off when it got warm enough to ride. Shame, never been able to duplicate that paint combo.
Forgot the say the power is great with this 92 from way out, as good if not better than the city gas and the change from stock air box and headers.

[Rasputin]

Tried the sea foam and the results were disastrious to say the least. Will noy go there again ever!

[donebysunday]

Wonder why ? Works for me and not for you ?

Next thing I tried was the blue Stabil worked well too and cheaper in the long run.

[KA1J]

Rasputin, a friend I play music with owns a marina on the RI coast and I asked him what people use in their boats regarding fuel separation, moisture & ethanol problems and he said to use Star Tron, that from what he's seen as of late, the people that use it have far fewer fuel issues than those that don't. He's not prone to pass along BS so I'm sure he means what he says about it.

http://mystarbrite.com/startron/

Here's an interesting video but I could do without the drums & dramatic music in the beginning.

http://portal.sliderocket.com/AUOTI/Star-Tron

I can't wrap my head around whatever it is that the enzyme works on, enzymes for the most part are proteins made of long chain amino acids & this is a large part of what makes biological cells work. There are another class of enzymes called biocatalysts that work on organic compounds & perhaps that is what Star Tron actually uses as ethanol and gasoline are for sure organic compounds. But to the best of my knowledge biocatalysts are confined to living cells.

I started using it this year and who knows, maybe it actually does help the MPG and gas to remain stable? I've been using it for 2 months now & will use it over the winter. I have already set aside two quart jars 3/4 full of gas; one is untreated and the other I added 2 CC of Star Tron. I'm leaving them in the shed where they'll get cold this winter. I want to see if there's any observable difference next spring.

[TopCatGr58]

Hey there KA1J,

We've had this type of discussion before. The mileage you are quoting is exceptional.....I'm lucky to get a bit over 30. I do have my bike jetted a bit richer, and I use 93 Octane because of the little big bore kit with slightly higher comp ratios than stock, and didn't want to take chances burning holes in my new pistons. Yes, alcohol is less power than straight gasoline, and so let MPG/Bang is expected when using ethanol. The speed that you are tryiing to push your bike/block thru the air is the major factor, don't recall the exact specs, but once up to like 50 mph or so, an increase in 10mph requires many times the power/fuel. When we run the twisties during our rallies, we are usually running a bit slower 20-50 mph vs. the 65+ hwy speeds, and even though I'm cranking mine up to 6+K rpm often and sustained, I was surprised to see higher mileage than my highway running!

Higher octane burns slower, but if needed, will help to burn more evenly within the combustion chamber from the flame front/plug downward vs. lower octane that can pre-ignite in another location other than the spark plug=knock, and could contribute to incomplete burning.

1179cc Wiseco kit, Stock carbs, 117.5 mains, 45 pilots, Indy Pods and 4-1 pipes, Dynatek hi output coils/no resistor caps. 81SH....modified!

T.C.

[KA1J]

heyya TC,

Funny, I always figured the 1100 series would be expected to get in the 40's for MPG. I didn't realize that was not the usual.

My XJ11 was getting 34 MPG at best 4-5 weeks ago but a friend came over to help me find the problem with my Maxim X on cyl #4 which showed as a heavily carboned plug even though compression was good and I had completely rebuilt the BS33 carbs. (The problem turned out to be an ovaled emulsion tube). He replaced my bad tube with a good one he had and he also replaced the pilot jets with new Mikunis. That took me from a max of 36 to a max of 48 MPG. That pretty much stunned me to get such a difference and I looked to the XJ11 to see what I could do with it.

I had been running in it, a set of XJ11 carbs I had cleaned thoroughly and put a Dynojet stage 1 kit in, including their slide needles and I drilled out the vent hole in the slides though the difference in hole diameter was almost nil. According to the dynojet literature stage-1 was for me because the only I/O mod at the time was a K&N air filter & I had stock exhaust.

I picked up a 2nd set of XJ11 carbs and they were waiting to be cleaned so I decided to make them restored as stock. I replaced all the rubber in the 2nd set of carbs except for the diaphragms and end of the enrichment plungers/dust caps, new Mikuni pilot jets, main jets, pilot adjustment screws/spring/washer & O-ring, went OCD in cleaning all the passageways. Emulsion tubes are unobtanium so I made sure these were all equally round and then color & carb tuned it. - At the same time I upped the tire pressure from around 34 to 39 fore & aft. To try and be as "original" as possible, this time I removed the YICS eliminator after syncing. (It runs rougher at lower RPM with the eliminator missing but runs great at 1300 RPM & up) I'll use the eliminator every time I check the sync and I usually do check the sync every 600 miles or so. It's easy to do and only takes a few minutes so why not, I like seeing all the bars at the same height.

This time when I took the bike on the highway with the stock carbs, I thought I could feel a little less power but it still had plenty of go. The mileage I got was around 40 but that was a combo of in-town & mostly hwy riding. When I took it on the highway for a 100 mile ride at 65-75 I got 41 & change in MPG. Driving the trip just below the speed limit got me that 42.97 MPG. FWIW, I felt buffeted by the winds more on the way back. Not sure how that works into the MPG numbers, the wind though was not at my back and my head was always correcting. It was easier on the way up.

I'm going to replace all the pilot adjusting screw assemblies in the dynojet carbs and then put them back in & see what happens. I'm thinking the loss of power I felt going back to the stock carbs is maybe the lack of the instantaneous snap I got with the dynojet carbs. All things being equal, it'll be interesting to see how much benefit/loss there is with the dynojet kit. For sure there will be more power. Perhaps I can drop the slide needle one level to not use as much gas and still have the snap & power.

[jetmechmarty]

I don't get those MPG numbers either. 30 mpg is the norm for me. 4 into 1 exhaust is the only real deviation from stock. I use whatever octane I can get without ethanol. Right now, the closest place to me has 89. Most places are 93 only, but my machine runs great on 87.

[KA1J]

Marty, I don't get why my MPG numbers are at the upper end. Since you never know what a PO did to your carbs and I installed all new Mikuni jets & kept the ones I removed. After seeing the difference between mileage in the Maxim-X after the pilots and worn emulsion tube were replaced I went on a bent to get the XJ11 carbs as "new" as possible. Perhaps that was a big factor?

I remember reading it was important to be sure to get original mikunis in that other jets have their own numbers and the sizes of the holes are different. I remember seeing a chart showing various jet numbers by manufacturer and their respective hole sizes. I made it a point to only buy OEM yama part numbers for the jets. Buying them may have been a waste of time as the old jets may have been perfect, I just did it so I knew the carbs would be as-new and unmolested when I put them itn.

I'd done the same with the dynojet except I used their jets. Definitely more snap with the stage 1 carbs. Like I mentioned, I am obsessive about the sync being dead on and I do check that every several weeks. I'm still asking basic questions I need answers to so I don't think I know a better mousetrap.

[BA80]

My bike hates the higher octane fuel. I feel a marked decrease in performance with higher octane.

I didn't vote on the mileage part because I didn't see that I was supposed to have 2 votes there. The best I've gotten is around 42 - 44 but normally it's around 33 - 35.

[jetmechmarty]

My bike hates the higher octane fuel. I feel a marked decrease in performance with higher octane.

I'm not going to go that far, but I certainly do not realize any benefit from higher octane fuel. If the performance is decreased, I can't really feel it. I only use it to avoid ethanol. When real gasoline is available in lower octane, that's what I buy. Ethanol may not hurt anything running the bike every day, but I like to encourage those folks who are keeping 100% gasoline in stock.

[BA80]

My bike just doesn't pull as hard with the higher octane fuel, probably because it's tuned to the 87.