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

[Crusty Snippets]

Mpg

Fuel economy is awful, was 30 something to the big gallon.
Use the cheapest 87 gas for both bikes. Sidecar on Yami uses even more fuel.
Bikes in general have too much windage. Decent fairings would make a big difference.
Unkle Crusty

[KA1J]

Saw an interesting bike/sidecar at Rice-O-Rama in Oxford MA a couple of weeks ago. Looked like it was made out of metal plating, the kind you walk on with the raised "dutchmen". Very well built and looked to be military grade.

[Zeke on Wheels]

My bike didn't seem to do any better on the higher octane either. I burned the 93 for the first few tanks when I got her last year because it seems like I read that I was supposed to on a sticker or something. However, after finding this site and switching to 87 octane, she runs just fine.
If I ride it like I stole it, my mileage goes down a bit into the mid-high 30s.
If I take it somewhat reasonable (is that possible with these bikes?) I average 40 MPG.
I drive to work about 15 miles a day, averaging about 60 MPH, except for the 3.5 miles of gravel road that I have to travel. I limit myself to 25-30 on gravel roads, so that might come into play. Sometimes I do take the freeway home, which means that I drive about 75-80 for half my drive and then only 1 mile of gravel.

All in all, over time my average stays pretty steady at 40 MPG.

[fredintoon]

Wonder why ? Works for me and not for you ?

Hi Done,
perhaps it's because you believe in snake oil and he don't?
more likely it's because his winter temperatures make yours look like a mild day in autumn.

[Rasputin]

Hi Done,
perhaps it's because you believe in snake oil and he don't?
more likely it's because his winter temperatures make yours look like a mild day in autumn.

It was - 2 this am so maybe you have hit on an explanation for the variables!

[MPittma100]

Octane/Ethanol

I went to Bryson City Thursday of last week with a tank of regular ethanol gas in the tank. Got 36.5 mpg on that tank that day. Filled up with premium non- ethanol gas. Next days ride was similar and I got 40 mpg. There was a noticeable improvement in the bike's performance as well. So it was either the premium or the non-ethanol or both. But there was a big difference. Have not tried regular non-ethanol yet. I'm sold - no more ethanol for me in anything but cars.

MP

[jetmechmarty]

I'm sold - no more ethanol for me in anything but cars.

MP

Good luck finding pure gasoline in Roswell. The closest vendor to me is eight miles and it's 89 octane only. 93 octane is available in Suches and at Turners Corner. I have to go to Blairsville for 87. At a rally based in Townsend, TN three weeks ago, I was able to run pure gas all weekend.

[skids]

On other bike forums, it is claimed that the ethanol gasolines can gum-up valves and make the stick open. I suppose this is plausible because of the cooler burning.

[KA1J]

Something I find that doesn't make sense is I do get better gas mileage with the higher octane gas I get here in New England. What doesn't make sense is the XJ11 like all of our 1100s has a fairly low compression ratio so it doesn't require higher octane. And, none of the gas I can get is pure gas, it's all been adulterated with ethanol in my area of New England.

I mentioned I've gotten 43 MPG (42.97 MPG) with my XJ11 but it was with around 91-92 octane (I mix 93 & 87 octane, it's cheaper than buying 91 octane). I've never gotten those high mileages with 87 octane; all my high MPG is with higher octane than the minimum.

[jetmechmarty]

all my high MPG is with higher octane than the minimum.

You can tune for high octane. High octane fuel will tolerate more spark advance than regular.

[KA1J]

You can tune for high octane. High octane fuel will tolerate more spark advance than regular.

I've heard that but I haven't done anything to the ignition except dynacoils, 8mm wires, zero ohm mod to the plug caps & Iridium plugs. I've never touched the advance, I don't know how to with these bikes. Maybe a PO did that in the past and it now runs better with higher octane? No pinging with 87 octane though.

Yet another mystery I'll never know the answer to.

[ExcessiveBiker]

Mpg

Hi, Y'all,
I live and work south of Houston, and ride 27 miles to work, doing around 11,000 miles/year, just riding to work. I have two 11's (SH and a Venturer), that are basically stock, with IV Vetters. Both needed carb and brake work when acquired. Carbs were gone through once and bench synced, only. The floats were set by fuel level sight tubes, also on the bench. The SH has 60,000 plus, and the H has near 10,000 since the carbs were set. So far both run spot on, no falters and easy starting.
Now to the gas mileage. I run cheap gas with ethanol, and a couple oz. of seafoam in each full tank. If I run the p___ out of it, MPG is 33-35. If I old lady it, MPG is 30-32. This improvement seems to relate to higher rpm, rather than ultimate speed. There are many lights and cager passes on my route, so there are a lot high rpm takeoffs and dodging traffic. Some weeks the traffic gets wadded up, and I can't blast around properly (old lady days), the MPG suffers. Both bikes are geared to run 70 mph at 4 grand, so the only difference in MPG, seems to come from higher twisting between 1st and 4th gear.

More variables to consider.

ExcessiveBiker
81 SH
81 H

[natemoen]

Don't know how you get 70 mph at 4k, stock setup with the standards 4k is 60 and for the special it is about 4.5k for 60.

[jetmechmarty]

Don't know how you get 70 mph at 4k, stock setup with the standards 4k is 60 and for the special it is about 4.5k for 60.

It could be the tach. My first one had 55 mph at 3500 rpm. I found one with a better face and it shows nearly 4000 rpm @ 55 mph. The current one seems to stop at 6K, so I'll be changing it again. I always suspected the first one to be spot on because my XS650 with stock sprocket sizes turns the exact same RPM at speeds. So, maybe he has a slow tack and/or a GL1000 gearbox.

[IanDMacDonald]

I've never paid much attention to rpm ranges except one number: 80mph= 5200rpm on my bike.