StromTrooper banner

1 - 13 of 13 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter #1
Howdy, folks! I've been doing some searches, but I haven't found much to go on beyond bits and pieces that I'm using to trouble shoot. I'm looking for some assistance in figuring out the cause of a dramatic decrease in my miles per gallon according to my onboard gauge.

Here's the deal:

I bought my bike in February with 14.2k miles on it. As part of the deal at the dealer I had them check valve clearances, and the tech said they were in spec.

I've put a little shy of 2k miles on it, and the onboard MPG has been clocking me between 42-50 MPG depending on how much highway vs city commuting I've been doing. Four weeks ago I cruised it to the top of a 9k ft mountain on the edge of town and back down to my house I was at 52mpg by the time I got back to my house. After commuting the rest of the month I was at 41mpg.

This past weekend I set off to Yuma, about a 230 mile trek, and I glanced down at my dash and saw the MPG was was 34. I was cruising at 75mph in sixth gear, right around 6k rpm. Confused, I reset the trip counter, and quite quickly my average dropped all the way to 32mpg. This stayed true all the way to Yuma. I dumped 5.1 gallons into the tank on the edge of Yuma, and had topped the tank off in Maricopa County maybe 80 miles in.

The return trip was much the same, 31.4 mpg according to the onboard gauge.

The bike is running fine. It seems to be running just as it did when I took ownership of it four months ago though it does seem to have more pronounced engine braking if I get off the throttle.

On the way to Yuma I bummed a paper clip off a gas station clerk and put the bike in diagnostic mode. It was not throwing any codes.

In a couple days I'm going to pull the tank and install a K&N filter, do an oil/filter change, and pull the calipers to reset the pistons to make sure they're not dragging. I considered spark plugs, but it seems highly unlikely they'd be due for replacement since the mileage is relatively low. I suppose it wouldn't hurt to pull them and have a look since I'll have the tank off.

Is my trouble shooting on the right track, or is there some other stuff I'm missing? For context, with gear on I clock in at 225 pounds. The bike has OEM boxes and racks on it, and OEM spoked wheels with Shinko 804/805s with about a thousand miles on them.
 

·
Registered
Joined
·
3,877 Posts
75 mph seems to be where the gas mileage starts to takes a hit.

With the boxes, 50/50 tires and you being on the large size there's a lot of resistance. Were you going into the wind? Hot weather will effect mileage also.

I saw low 30s when I had my 650 at 75-85 mph. On my 1000 I've seen low 20s in the same conditions.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #3
75 mph seems to be where the gas mileage starts to takes a hit.

With the boxes, 50/50 tires and you being on the large size there's a lot of resistance. Were you going into the wind? Hot weather will effect mileage also.

I saw low 30s when I had my 650 at 75-85 mph. On my 1000 I've seen low 20s in the same conditions.
On the way out it was in the low 90s at night, and on the way back it was high 90s and low 100s in the morning. I'm 6'6" so I can be a bit of a sail, but I guess I'm surprised by how dramatic the drop is from the tires because I was getting ~45mpg in similar conditions when I had 80/20s on when I put in a 300 mile round trip back in March.
 

·
Registered
Joined
·
1,528 Posts
Are you running enough air in your tyres? Low tyre pressure can make a difference both to handling and mileage.
Was there a decent cross or head wind on the trip? I noticed on a trip on my K9 a while back that the bikes takes a significant hit if I'm travelling with full luggage and there's much wind.
Have you recently invested in larger riding gear? If it's too loose it acts like a sail and causes a lot of wind drag.
Are you sure it's still showing miles per gallon and not kilometres per litre?
Put the bike on a stand and make sure the brakes aren't dragging. A small rock lodged in the brake caliper or the rear brake lever can cause all sorts of headaches.
 
  • Like
Reactions: Spec and Cryoman

·
Registered
Joined
·
173 Posts
Sounds like wind resistance and tires. Big difference in rolling resistance between tires and highway speed into the wind can drop the mpg quite a bit. Those are chunky tires and I noticed a small difference between Bridgestone T31 sport touring vs. Metzeler Tourance adventure tires.
 

·
Registered
Joined
·
2,054 Posts
My 2014 does this at highway speeds. My wife and I headed out to Utah 2 weeks ago and the speed limit on I15 north of St.George is 80 mph. It's slightly uphill and it was windy so my onboard mpg shows in the high 20's. Got up in the mountains at lower speeds (under 65) and temperatures, it goes right back up. I'm running Tusk boxes, Madstad windshield and Michelin Anakee Adventure tires. I also weigh 10 lbs more than you.
 

·
Registered
Joined
·
91 Posts
With panniers and tail bag and doing ultra legal "you're going to have to park that and walk son" speeds from south of Raleigh NC all the way out until I hit 28 to and Deals Gap, it definitely tanks the mileage. For the all highway parts I recorded about 44 MPG. For the all mountain parts from that weekend I ended up at 52 MPG. This is where the speeds probably averaged 40 MPH for the most part. On the way back to my house from the mountains at a much lower speed, about 5 over, it gave about 48 MPG. High speed with you and the attachments are just going to bring the mileage down in a hurry.
 

·
Administrator
Joined
·
17,094 Posts
Yeah I can see some pretty big dips once above a constant 70 MPH "or faster" and loaded up, never dip below 40 MPG though on my bike since buying it new in 2015. Tires do make a difference, bags on or off make a difference, temps make a difference, going into a headwind makes a difference, elevation makes a difference, so yeah some decent size MPG swings can be had especially on these 650's compared to the 1000's.
 

·
Registered
Joined
·
3 Posts
Discussion Starter #9
Thanks to everybody for all the feedback and personal experiences! This is all very helpful.

I'm wearing the same gear I always have, and haven't really been encountering much wind.

Commuting to work so far this week has me at 35mpg, but it's a lot of stop and go on a very short commute so that's to be expected, I guess.

After I do the filter and oil on Monday I'm gonna take a ride out to Bisbee for a michelada at St Elmo on Tuesday or Wednesday. I'll do state highways there and interstate back so I have some numbers to compare as far as 55mph vs 80mph cruising.

I'm guessing these blocky tires have a lot to do with it. I knew there'd be a dip, but I'm kinda amazed it might be this dramatic. Obviously I won't be saving myself any money swapping them out before they're burned up, but I doubt I'll do 40/60s again if it really is gonna eat up a solid 25% of fuel economy. They ride great when I'm cruising state trust and BLM land around Southern Arizona, but I only do that once a month and the rest of my miles are pavement. I chose this bike over a KLR or DR specifically for better highway manners on long hauls, and getting only 3 or 4 mpg more than my Ranger is kinda whack all things considered.

Y'all have any recommendations for tires with lower rolling resistance that still have acceptable traction on BLM roads and fire roads? I don't touch anything rougher than tame Jeep track when I'm out in sticks, mostly loose sand and dirt over hardpack.
 

·
Administrator
Joined
·
17,094 Posts
The big blocks never made that much of a gas mileage decrease for me, and they are the best all around tires for IMHO in terms of where/how the OP likes to ride.
 

·
Registered
Joined
·
55 Posts
With panniers and tail bag and doing ultra legal "you're going to have to park that and walk son" speeds from south of Raleigh NC all the way out until I hit 28 to and Deals Gap, it definitely tanks the mileage. For the all highway parts I recorded about 44 MPG. For the all mountain parts from that weekend I ended up at 52 MPG. This is where the speeds probably averaged 40 MPH for the most part. On the way back to my house from the mountains at a much lower speed, about 5 over, it gave about 48 MPG. High speed with you and the attachments are just going to bring the mileage down in a hurry.
Well hello neighbor, also South of Raleigh.
 
1 - 13 of 13 Posts
Top