Fuel Mileage after THE mod

[MAXIMAN]

For those who have done the final drive mod post your mpg results.

Then tell us about your bike. The best mileage at highway speed of 70 I had seen in Zilla pre mod was about 33-34. After the mod at 70 I realized about a 5 to 6 mpg gain with a max mileage of 40.5 mpg. I repeated this twice to confirm the kill.

On my road trip to west Texas at 88 mph on I-10 I saw 37 and 36 mpg on two tanks. For those that may not know it...Zilla is a full dressed bike with bags and trunk and lowers. He has a lot of wind drag and weighs more than locomotive. I am very please with these numbers and for long distance cruisng this mod is the DE FACTO standard in coooooooooool!

Please DO NOT respond if you haven't done the mod.

Thanks.

[xschop]

mod miles

I average 44-45 mpg's now and I don't baby her....before the FD Mod I averaged 37 mpg's....No windshield, No Frills, just 210 lbs of me.... I also stay at 70-75 mph in 5th on the long hauls...

[DiverRay]

I was getting about 38mpg on my commute. I now get 42mpg, sometimes a little more. My commute goes from sea level, to 1800' elevation, and back to sea level in 35 miles. I do this twice a day, once each way. I almost always hit 100mph+ on the way to work in the morning, just to make sure the bike will still do it.

[underdog57]

Glad you put up this Poll Max ...
Really a worthwhile mod ....
I'd like to get 20 plus miles more out of a fill up !!
get about 36 mpg stock ........

Bob

[John]

Depends on what kind of driving I'm doing. Slow country rides, I ge about 40 mpg, and on the freeway, I get about 34. I can now get over 110 miles on a tank.

[red bandit]

I get 36-38 once in a while I get 39 mpg. Stock 79 standard, windjammer hard bags and truck. Gas mileage didn't change any after FD mod. 60 mph, 3100 rpm steady country cruising around here. Any faster than that and you get to talk to Mr. policeman. I'm guessing I'm not pushing the engine enough to see any milage gain?? I figured up the rotations the crankshaft isn't turning and the numbers were significant in 1000 miles, course I can't remember what the numbers were but it's an engine saver.

[underdog57]

The faster you go the worst the gas mileage should be ...
no matter which drive you have .

Bob

[MAXIMAN]

Originally posted by underdog57
The faster you go the worst the gas mileage should be ...
no matter which drive you have .

Bob

Not entirely true in all instances. Generally that is indeed the case but here's an exception to the rule.

I found this out for a fact and have two witnesses to testify.

In west Texas the speed limit on I-10 is 80 mph. You can actually ride 85-90 and the DPS won't even notice you.

We rode rode in west Texas for a couple days. At 70 or less I get the best mileage...about 40 mpg. At 75 to 80 Zilla was getting about 34 to 36. But 85 to 90...if I held my speed about 87 or 88 mph....the bike would get 36 to 38 mpg. I repeated this 3 tanks. We (me and two other XSives) were all amazed but apparently Zilla is an anomoly. There is a sweet spot on that bike that likes 88.

If I push him into the low 90's mph he'll drop back into the 34 and under range.

The bike is tuned. The AF ratio is correct. I've had that machine on the dyno/sniffer just a few days before we left on the trip. So I know it was spot on when we left.

[pggg]

You people are sayin' you're getting 35mpg, US gallon, thats 42mpg here, imperial gallon, at 80 and 90 MILES PER F## HOUR!!? Means you're doin way over 50 mpg(imperial) at 55 - 60mph?? On the notoriously thirsty gas gazzling Yamaha XS1100?? That's incredible...

[xschop]

mpg's

I am really curious if the folks at higher elevations (above 3000 ft)would be better off with 4-2 pipes rather than 4-1....because of the HP loss as you go up in elevation....

[MAXIMAN]

Imperial gallons!?!? 50 mpg?!

The "King" always was aliar. That's why we parted ways.

But seriously...I took extreme caution and paid specific attention to detail when I refilled the bike on the trip.

On the three tanks I spoke of I always put the bike on the center stand and made sure the bike was level. A quick way to do that is look at the oil level in the sight glass. Everytime I filled it ...the oil level was in the same position. So all variables were fairly constant.

The first tank I went from Brady to Ozona 157miles on 4.06 gallons.

The second tank I went from Ozona to Ft. Stockton 111 miles on exactly 3.0 gallons.

The third and final tank was from Ft. Stockton to Alpine 68 miles on 1.75 gallons.


I took notes if you noticed. Anywho...all three legs of this part of the trip we were cruising about 85 to 90. The other guys were not getting anywhere near this mileage at that speed. I think my hopped up Eleven obviously got much better fuel mileage than there stockers. Miles was on a stock '81 SH with a fork mounted windshield that has the aerodynamic design of a 4x4 sheet of plywood. He was getting 29 to 31. He doesn't have the mod installed.

Bohn was on a stock (pristine I might add) '80 SG full dresser. He does have the mod and he was getting 32 to 34 at that speed. But he has no performance mods like Zilla.

When we slowed down to 70-75 Bohns bike would jump up in the 36 to 38 range. Miles would jump up in the 34 range and mine would actually fall!!! back to around 35 or 36 mpg.

[trbig]

I have the mod, but honestly my gas mileage didn't change at all. As Underdog57 wrote, you should get better mileage the slower you go.. BUT... I have found that on the freeway when I keep the bike between 80-85, I get the best gas mileage.. @40mpg. At 70-75, it drops to @ 36-37.

Even though I didn't realize the fuel savings like others have, the bike just cruises so much easier now. I don't find myself at freeway speeds trying to grab another gear periodically like I used to. So the money isn't saved on the fuel, but this has to be easier on a motor, letting it last longer. How much money is that worth?? That's the savings I'm looking at. It dropped my RPM's by 700 at 75mph.

Tod

[MAXIMAN]

Chop

We are going to find out! After the following mod I'll be taking a trip through the rockies and into California...average elevatoin will be about 4000+.

I am waiting on some megaphones to be re-chromed. Once they are finished I have dreamed up a SuperTrick Supertrapp exhaust.

I bought a slick 4-2 Jardine Spaghetti pipe that flows into megaphones. This is the version with the cross-over tube between the megaphones.

I pulled the mechanical baffles and did some measuring. I found some 2" straight flow through baffles from Supertrapp that are wrapped in ceramic fiber. These baffles look identical to the baffle in the can of my ZRX thats flows like a river...but is still fairly quiet.

I also bought two Supertrapp difusser caps with 12 plates each to attach. So I'll have a 4-2 jardine megaphone flowing through two Supertrapp cores.

I plan on Documenting this deal and sharing what I find out. Once I get it installed I will have the bike dyno tuned again and see what I lost or gained. I'm guessing there won't be much change but this exhaust should be more quiet and much more aesthetically pleasing to the eye being it is dual chrome megaphones.

[Rubin]

41-42 mpg post mod, this has been confirmed after three tanks so far. I was originally getting 34 mpg consistently, all using the same roads. I cruise around 75-85 on the freeways in the US, and around 65 in Canada. I used to switch to reserve at 220 km (137 mi), and can stretch that out to 265 (164 mi) these days. I think I might be able to reach 300 (186 mi) with reserve, but I really don't want to test that one out if I don't have to. 285 (177 mi) km has been reached so far on one full tank with partial reserve used.

This is by far the best mod I have done to this bike. Not a full dress, but she has a windscreen and hard luggage and will soon have a trunk. Many of the above miles have been attained 2up, though between the two of us we are only around 260 lbs (118 kg, or 18.5 stone).

[Shuriken]

Chop,

I've had a tough time getting my XSs to run well at my elevation no matter what pipes or mods I've employed.