Tire pressure & mileage question

[KA1J]

I asked this elsewhere but would appreciate the input from this forum. I'm assuming the XJ11 & rest of the XS11 family are similar enough that MPG is close to the same on all

I have just rebuilt a set of XJ11 carbs and I took my XJ11 out today for a very long ride, mostly on the interstate. I used to have my tires (Michelin Commander II) at 32 front & 34 rear and the carbs were set up with dynojet carbs stage 1. With that my best mileage was 34 if I drove like a little old lady.

With the #2 set of carbs set to factory specs, with new jets, a complete carb overhaul and with tires now at 39 in front & back I got 41.7 MPG US gallons driving between 65 - 75 +/- all the way.

A big difference but since I changed both the tire pressure and put in factory speced carbs at the same time, I don't know which made the most difference. I do know that almost 8 MPG increase is respectable & I still haven't yet driven it like a little old lady to see the max mileage I can get from the stock carbs.

I also haven't put the carbs with dynojet stage 1 back in now with the increased tire pressure to see if the MPG will change. (There's more power with the dynojet kit but nothing comes for free & I'm guessing the MPG will go down?

So I'm curious how much pressure people are putting in their tires and how they're doing for MPG with their XS11/XJ11. - If you wouldn't mind posting your tire pressures F & R and actual highway MPG as well as filling out the poll, it'll be interesting to see what comes up.

Gary

[motoman]

42-44psi front/rear of both motorcycles. Bias on Venturer/Radials on ST.

[CatatonicBug]

I think 44 is the standard pressure for both front and rear, unless you do any rough-road riding (unpaved access roads and the like). I haven't measured my MPG in a while, but I don't exactly baby it. the best I've ever gotten was 44 MPG right after I installed the dynajet kit, on a group 55mph ride for an entire tank.

[natemoen]

I run 40psi front and rear. I have heavy metal ammo can saddle bags on the back and a pacifico fairing on the front. I get about 36 mpg both highway and in town.

[JeffH]

I run 40psi front and rear. I have heavy metal ammo can saddle bags on the back and a pacifico fairing on the front. I get about 36 mpg both highway and in town.

+1
My 11E with Pacifico I run @40-41 psi front & rear. After rescue project rebuild last year was getting normally 37 mpg. Now after more work this year and new Dyna coils getting 38 mpg. Normally run at 65-70 mph everywhere and hard in the mountain twisties. 4,500 rpm gets me about 72 mph in top gear. I got bike setup for my riding style and bike runs good at all rpm's. I would think I could maybe hit 40 mpg just doggin' it at a steady 55mph, but have never tried that.

Jeff

[MPittma100]

11E Venturer

40 psi front and back. This past Saturday with ethanol in fuel got 36.5 mpg after riding in Deal's Gap and Cherohala Skyway. Sunday same tire pressure, similar riding conditions, with non-ethanol premium, got 40 mpg. Siginificant difference. Have gotten 42 mpg previously flat tracking (with ethanol fuel). Bike had noticeably improved performance (seat of the pants) with the better fuel. Not cheap, but very good gas compared to ethanol gas.

The fuel station (King's) that has non-ethanol fuel only is located on Hwy 74W at the intersection of the highway (forgot the number) that goes to Franklin on the way to Bryson City from IH. We went that route to Franklin at last years Rally.

I will use non ethanol gas in the future for bikes, 4 wheelers, chain saws, generators, etc. whenever possible.

Ethanol causes too many problems. Two motorcycle/4 wheeler dealers told me that 95% of all carb/fuel related problems that they repair is caused by ethanol. I have spent all that I intend to spend on ethanol related fuel system problems.

MP

[trbig]

It depends on the tire. Conti tires have a max psi of 60. The Shinkos I have now have a max of 40. The higher the inflation, the less rolling resistance, the higher gas mileage, the lesser braking/stopping power. The lower the pressure, the more rolling resistance, the lesser gas mileage, the more stopping power.

Find what's the best of both worlds for you that you can literally live with.

[skids]

It depends on the tire.

Ditto! It is per the tire make.

[KA1J]

Good heavens, 60 pounds is like a bicycle tire!

The Proper tire pressure still seems to me to be a matter of taste as long as it stays within the tire makers specs. Tire construction has changed in 30+ years and I've pretty much always felt the vehicle manufacturers ratings were more to create comfort and a cushy ride with wear and mileage not part of the equation. If a tire is "grippier" today than its counterparts 30+ years ago, why would you need to maintain the same tire pressure if it works properly at a higher pressure?

I came back from Boston today and thanks to an idiot ahead of me crossing two lanes to make an exit, I had to swerve and brake hard. Brakes worked perfectly and the swerve was under control, felt like I was on a slot car. I've got Commander II tires at 39 pounds in front & back (Think the max is 42 PSI if I remember right). I read in various forums where people are getting 25K miles with these tires but no mention as I recall of the tire pressure or weight of the vehicles.

O'course, the amount I don't know is impressive...

[fredintoon]

This is a spin-off of a tire thread and I think it's asking the wrong question.
XS/XJ 11s suck gas like a drunken sailor anyway, the average newer car gets better mileage fer chrissake.
What we should be looking for is what tire pressure gives the best handling.

[CaptonZap]

What we should be looking for is what tire pressure gives the best handling.

40 psi, front and rear.

CZ

[Jerry]

I ran the XJ (Vetter fairing and bags, Dunlop Elite III front and rear) at 36 front and 40 rear. I weigh 265. Run the '06 Concours, same basic set-up with factory fairing and bags, same Elite IIIs but different sizes, same tire pressures. Got about 32 mpg on the XJ, get 42 on the Connie. Carbs on both bikes are stock but the Connie has a 6-speed tranny. 75 mph freeway speeds on my commutes to and from work. Elevations range from around 5K feet to just under 6K feet, engines don't make as much power here as they do at lower elevations. Only fuel I can find has 10 percent Ethanol added, ethanol cuts your fuel mileage.

The Vetter fairing on the XJ cut my mileage by about 3 - 4 mpg.

So, lots of factors go into fuel economy, but if you are getting anything from the low 30s and up you are doing about average. Over 40 for an 11 is exceptional. Not unreachable but not common, either.

My Honda Accord gets about the same mileage as the XJ so I don't ride for mileage. Now the Connie gets much better mpg so I do ride it partly for mileage gains, but I run 91 octane in it instead of 85 or 87 so the price per gallon is higher and offsets some of the better mileage figures. I really don't save much over running the Honda on 85 octane versus running the Connie on 91 even with the Connie's higher MPG figures.

Bottom line is that I don't ride for economy but for the enjoyment of riding. If I can reasonably save a few bucks on fuel that is fine but is not a top priority.

[donebysunday]

Tires

I've been running 36 psi. front and rear and getting 30-39 mpg. I may up my pressure to see.

Not to change the subject but what all you all running for settings on the air forks and pre-load and damping on the rear shocks ?

Thanks ! Done };~)

[skids]

I run till they are flat and then pump them up again ... We'll, not really but I don't Check pressure often.

[mjpxs11sh]

+

frt 36 rear 40 on my 81 SH w Kerker and Unifilter in stock air box. my best hywy mileage was 49 avg is 40-45 and thats not nec takin it easy! may be hard to duplicate lol