46.9 mpg!!!


Today, I took a solo ride of exactly 80.2 miles, with two rest stops along the way, including a place to get lunch. The ride was over a variety of good roads about half of which were on the interstate at the speed limit with a few FULL throttle blasts in high gear of several seconds each. I didn't notice my actual top speed, but judging by the freeway traffic conditions, it was probably around 90 (+/-5) mph each time I cracked the throttle open.

The other half of my ride was on a mountain roads, about 15 miles of which was almost continuously up hill at about a 15 degree incline.

The average OAT during my ride was in the low 70s on a near windless day; a perfect day to go riding! My bike has a Summer Windscreen, (which of course increases aerodynamic drag), and I weigh 260 lbs.

I reset my trip odometer at a Chevron gas station and precisely filled up with 87 PON to ~1" below the top of the gas tank filler neck. When I got home, I filled up again to exactly the same level. It took 1.711 gallons, so my average fuel economy was 46.9 mpg. Not too shabby!

A few other observations:

If not for more "spirited" riding on the freeway, I probably could have average 50 mpg!

Based on this measurement of my EFI Bonnie's average fuel economy, a full tank of gas should be good for just over 200 miles per fill up.

My TORS really "wake up" and make themselves heard with a somewhat throaty sound at around 5500 rpm.

My engine oil temp heated up to a WHOOPING 270F by the end of the 15 mile up hill grade mostly shifting between 3rd and 4th gears at a leisurely pace.

I only saw three other Bonnies (two vintage) during my entire ride, all parked up at Alice's Restaurant on Skyline Blvd (at the intersection of CA Highways 84 and 35).


It's a fairly new bike and I'm just over 500 miles, so I have yet to change the factory fill's so-called "break-in" oil, but I share your concern. I absolute do plan to change the oil after my next ride with the "good stuff".

Remember, the oil temp sensor is located on top of the oil cooler (LHS) at the "inlet" port. This is the hottest point in the lubrication system, because this is where the oil flows from the engine's cylinder heads to the top of the cooler. On the other side of the cooler (RHS) at the bottom is the lower temp, oil return line to oil sump at the bottom of the engine.

I'm not sure why Triumph designed the engine so the oil flows this direction. The heads are already at the hottest temp, but receive the least cooling from the oil cooler. Can anyone else here comment on this?

Also, I have no idea how accurate the temp sensor is on these bikes, or the tolerance band. Mine could be way higher than actual. Nevertheless, when I got over the crest of the hill, parked at a rest stop for about 30 minutes to have lunch and let the engine cool off. Then, resumed riding for several miles on a slight downhill grade, at ~45 mph mostly in high gear. During this part of my ride, the oil temp dropped substantially to a cooler range of between 200F to 225F.

However, if OAT was much warmer, during the hottest days of Summer, I think my max oil temp could easily reach 300F on that same uphill grade. Needless to say, I generally avoid riding on warmer days!
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Two Stroke
As was stated, change your oil to a full synthetic. As you put more miles on the motor it will run cooler. The tolerances are still tight. Don't lug your motor in any gear.


I just realized I have the capability to "log" a whole slew of fuel economy statistics using my BT OBD2 dongle connected to the ECU (see topic called, DASHBOARD here for more particulars), which is feeding data to my 7" tablet computer mounted on the handlebars. I can continuously log mpg, fuel qty used, mileage, avg speed, top speed, day by day, and total "running" mpg. I'm getting seemingly very accurate mpg calculation based on ECU>OBD2 scanner logged data. My fuel economy using regular 87 PON Chevron gasoline is in the high 40s over a wide variety of different riding conditions, i.e. much better than expected since I'm a 260 lbs and have a full size Summer windscreen on my Bonnie.
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58.6 mpg 2016 T120 bonneville

Just got back from a ride across US and after 41 tanks of gas got 58.6 MPG some times as high as 70 MPG some as low as 45. Most of the time on back roads got better MPG in 5th gear than 6th. Fred V Bonaire, Ga.
On my very first ride-which was from the dealership to home-I measured the fuel consumption at 51 MPG. Looking forward to many future rides.


Street Tracker
I don't even want to know what my bike currently gets. Maybe 30 if I had to guess. Maybe.

That's about were I'm at. Even before mods I don't recall ever getting 40. Might be a problem with my throttle, as it's just to damn tempting to keep rolling it open.


I'm gettin' about 37mpg on the Thruxton...I can live with that. Damned if I know the oil temperature :poke:


I was getting 45mpg before I started fiddling with my bike ('06 with carbs). After removing the AI and installing TORs it dropped to about 42 or so.


My 2016 Street Twin averages 65 mpg in city/open highway riding, it's gotten 72 in open highway riding on one tank before, I found a station that sells ethanol free gas and that's all I ever run in it.