How low is low MPG?

[XJSRider]

New to me 93 1500A that I have put about 100 miles on, currently ripped apart for full overhaul. During those first 100 miles I had seafoam in the tank and was doing 95% city. Also gas for the first 30 miles was older, I got it to a low level then added more seafoam and topped it off with fresh fuel. I got 32.x mpg. I was ripping on it a bit, not just put putting around at 1500 rpm. I've since searched mileage threads and seen people into the 40s.

Is my mileage indicative of a problem with the bike? When I pulled the plugs to replace they all looked really good. I did not do a compression check but when running I pulled each wire individually and could hear the engine slow down a bit. Sound of the change was pretty consistent for each plug wire I pulled and the bike seemed to run great when tooling around town, power in every gear at every rev range.

How much does your mileage vary based on riding style? Thanks.

[blupupher]

100 miles is not enough to get an estimate of actual mileage, especially if you had old gas and seafoam in it.
Around town mileage is usually much lower than highway. I have gotten worse than you around town (I like the go stick).
I have gotten over 40 mpg with all highway driving keeping the speed below 70. Once you start going faster than that, you start dropping mpg quickly as well.

[XJSRider]

Thanks for response... I figured that my test may be bunk but I get paranoid about stuff like this, thanks for reassurance. I'll run a whole tank through in a few weeks when I get it put back together and sleep soundly in the mean time. I like the "go stick" myself

[AZgl1800]

the only way people are going to get 40 mpg out of the 1500s is to never exceed speeds of 40 mph or so, and to stay off the throttle.

I have owned two of them, and year end and year out, the AVERAGE for the year is 33 mpg.

I have a spreadsheet that documents over 5,000 miles for a 98SE and that is exactly what it showed with me meticulously keeping records. That spreadsheet has MPG readings from 22 mpg up to 40 mpg

the spreadsheet has a column for "Conditions" where I wrote in what was going on for each tank of fuel.

So, your one tank experience is not out of line.

Attached is a pix of just one page of it

[CrystalPistol]

On a GL1500 Lehman Trike with passenger, sometimes even a trailer too, I rarely got less than 34-35 mpg, but I seldom ran Interstate highways if other alternatives were available. On rare occasion, I even saw 40 mpg on a tank, but that was because I was running 40-50 mph on non interstate highways & roads, just loafing along.

I had a buddy pulling a trailer with his GL1500 two wheeler out west like Oklahoma, Kansas, NM, Utah, see his mileage in the mid to high 20s.

I once had a group of riders ask that we hit the interstate and get back to Va. faster after a several day's group ride, we did, and running '70 mph, I could see the gas needle lower each glance, it was guzzling gas.

No question, running interstates at 70 mph or more with the tach up above 3,000 will see a 1500 not sipping, but rather guzzling gas.

Off topic, but my '85 GL1200A had 4 carburetors, was a MC, not trike, and I never saw it dip below 40 mpg, & have seen 51 mpg over a day of running from home up into mid Ohio with co-rider. A GL1500 will not do that, not even a bike 1500, unless carried on a trailer part way.

[ct1500]

Most will report an average of 37-42 MPG on a decent running 1500. Like anything the systems need to be checked/tuned to achieve correct running status. Many will purchase a can of worms on a used ride that had fallen into disrepair/improper repair and those rides invariably report much less MPG. A quick mixture test with the cardboard.
viewtopic.php?f=14&t=17014

[dingdong]

I, 80% of the time on our 1500, ride 2 up pulling a trailer. Those times I average 30 to 32mpg. If I ride just 2 up without the trailer I average 34mpg. Averages are for interstate combined with side roads. I have ridden on the interstate with trailer at 85mph and the mileage drops to 24/25mpg. Disclaimer...I have a Tulsa tall windscreen. Then again I have ridden 2 up out west, example, in Idaho riding through the mountains down the Lolo pass, running 35 to 60 mph through the twisties. On that trip my 1500 got 48mpg. My brother riding his 1800 got 49mpg. His friend riding a Harley got 51mpg. SO, it just depends on riding conditions and guess what... It is what it is. Just ride and enjoy.

[ct1500]

Even the seemingly insignificant idle speed can kill fuel mileage if not set to spec on the 1500.

[joeincalif]

I have owned 3 1500 wings. A 92, 97 and a 98, I always got around 40 MPG and that is usually between highway and city riding. On our guys only ride where we would do mostly freeway riding to get out of town I would get over 40 mpg. As said before if you go over 70 MPH about 3000 RPM's you MPG will drop. The lowers I ever got was 25 but that was 2 up pulling a trailer coming out of Salt Lake City, UT going back to Calif going into a real bad head wind with a Tulsa Tall windshield on my 98 SE pulling a Bushtec trailer.

[minimac]

Like CT1500 stated, I usually always got 37-42mpgs, on my '93 Aspencade. I once got as low as 34, but that was hustling (a steady80+ mph) loaded for a weeks stay in the Michigan U.P.

[DenverWinger]

Worst mileage I ever got was 19.5 MPG. But that was the last tank of the last leg of 10 days and 4000 miles, we were almost home. Opened her up to 85MPH on the interstate, 2up, pulling camper trailer fully loaded to about 550# with a Slipstreamer (Tulsa Tall) pushing into a headwind.

I normally see 32-36 with that tall windshield, if just tooling around the countryside it gets over 40MPG easy.

[brettchallenger]

Like CT1500 stated, I usually always got 37-42mpgs, on my '93 Aspencade.

That is my usual range (in US gallons). I rarely ride two up, though much of my travel is on twisty country lanes. On a recent trip to London (225 miles each way) I averaged 37.5mpg going south - into the wind, and 42.5mpg coming back North with the wind behind me. Most of the time I was using cruise control at 70mph.

[Elmobile]

I had seen the “cardboard test” suggested before but kind of disregard it until ct1500 brought it up on his Aug 07 post. I have followed his advices before with good result so why not...
Cut my piece of cardboard and after a short ride to warm up the engine, I went ahead and start closing the air intake. AND even completely closed, the idle never changed, not even a hint. Clearly my IAT valve is not opening.
I have checked it before with my vacuum pump so I know it can open if vacuum is applied! One more thing to get fix.
However I have a couple of question: Would this adversely affect my mileage? I had the carbs resynch not long ago with a much improved throttle response as a result. Will I have to have it redone?
For now I am just going to leave it open. With the hot weather we have had lately it should not be a problem. Just want to know if my mileage will improve...
Please, let me know what you think!

[ct1500]

I had seen the “cardboard test” suggested before but kind of disregard it until ct1500 brought it up on his Aug 07 post. I have followed his advices before with good result so why not...
Cut my piece of cardboard and after a short ride to warm up the engine, I went ahead and start closing the air intake. AND even completely closed, the idle never changed, not even a hint. Clearly my IAT valve is not opening.
I have checked it before with my vacuum pump so I know it can open if vacuum is applied! One more thing to get fix.
However I have a couple of question: Would this adversely affect my mileage? I had the carbs resynch not long ago with a much improved throttle response as a result. Will I have to have it redone?
For now I am just going to leave it open. With the hot weather we have had lately it should not be a problem. Just want to know if my mileage will improve...
Please, let me know what you think!

I would call the hot air door in the snorkel as being "normally open" to allow fresh ambient air to the air box. Only at temperatures below about 52F is when vacuum gets applied to the door actuator closing the opening to outside air and allowing heated exhaust air via the "zip" tube from the left header. What you write suggests vacuum is being applied when it should not but first check that the intake air snorkel is indeed fastened correctly with the metal clip to air box which would give an erroneous result if not.
A sync at idle with hot air going into the air box would not change the results all things equal. If you were pulling in heated exhaust air when not needed firstly it would limit incoming air supply do a degree when working the engine and secondly would raise combustion temps a bit so it would affect engine power to another degree that will result in lost efficiency.

[Elmobile]

Thank you ct1500 for your comments.
Interestingly enough, I happen to check if I had vacuum in #2 pink hose, the one feeding the actuator just before reading your comments. There is no vacuum there. I used my mityvac gauge to do it. I try to “pump” some vacuum in it but it is open to atmosphere. So I think the 3 way valve is working so does the thermal valve in the air box...
It appears that my actuator is stuck with the duct valve closed. I had it working at one time but it must have ceased again since. As soon as I can I will get the snorkel out and check the actuator.

I also noticed an oil leak coming apparently from the head cover on the right side! Was not there on Thursday but showed up on Saturday! I am going to retighten the bolts to see if it help. If not the seals will have to be replaced!
Putting this old lady back on the road is a challenge, I am telling you! But getting there I hope...

[Elmobile]

Not sure if I shouldn't start a new thread...?
But for now I'll keep going here.

Today it is raining in Nova Scotia. Good day to spend some time in the shop.
I went ahead and remove the snorkel all together to check the actuator. All is working as it should and the duct valve was wide opened.
I followed by doing the "cardboard" test right at the air box opening. No change! I can close it completely and idle never move. At 1500 rpm, it will gain about 100 to 150 rpm after 30 sec or so and then stay there.
I am wondering if the air filter is sitting correctly in the bottom half of the air box. It does go in the groove but there is no seal there. I had removed the K&N filter which use to be there when I first got the bike and put the OEM filter instead. So I am not sure if there should be a seal of some kind between the air filter and the box?
I now want to make sure that the engine is breathing filtered air...! Always a good thing
Any comments would be appreciated.
Cheers.

[blupupher]

there is a groove in the top and bottom part of the airbox.
The K&N should have a matching "gasket" on both sides of the filter that completely seals the airbox.
I know when I was putting mine back together I did not get it sealed correctly the first 2 times. I kept hearing a "growl" that was not there before.
I found the K&N is a touch larger than the airbox grove, so is very difficult to get it sealed correctly. I found it easier to install the filter in the top first, then put that on the bike with all the plastic off around it (it can be taken it off easily with the plastic in place, but getting it back on is much harder).
I also put a little silicone lube on the rubber to help it slide into the groove better.

[Jetfighter3]

I own a 93 gl1500, I consistently get 40 - 42 mpg. I drive 5 days a week back a forth to work none of which is highway , 38 miles each way. My first 10 miles is in the city of Palmdale CA.93551 out to green vally then the next 17 miles is bouquet cyn which by no means is a straight road , then the last 11 miles is back to city in Valencia CA. STOP and GO. I do NOT drive it at 40 miles an hour, when I can I'm doing 60-65 a bit over the speed limit and through the canyon 40-60 mph. I ride it pretty much like a sports bike for the most part. I'm really happy with it, and yes I drag the pegs in the tight corners when I'm feeling young again .

[Elmobile]

I put the K&N air filter back in properly cleaned and relubed. I just got the seals for the head cover so I will start by replacing the one for the rear cover has it looks like my oil is leaking. Very small leak but I want it fix before going for longer ride.
With the OEM filter you have to use a seal for both half of the air box... I put that on my winter list and finish the season with what I have!

[XJSRider]

So I've made a lot of progress on the bike and have gotten to the "test ride it for 500 miles before putting the plastic back on" stage. This weekend I had the chance to burn out the gas I had in the tank then refill twice.

My first refill was spent riding 2 up, all back roads but a very brisk pace, 70-80 mph. Some city stuff but mostly faster country roads. Lots of faster starts, tach was between 3-4k most of the time. Got 34 mpg.

Second refill the passenger got off an hopped on her little 125, so my speed was capped to about 55. Slower starts. Never revved over 3.5k. On this tank I got 39 mpg.

Looks like riding style plays a big part. This machine had sat for a few years and was ridden very lightly the past ten, it seemed to like seeing some revs for a change.

[bellboy40]

You are certainly correct that riding style has a huge impact on fuel mileage. The engine rpm itself is not what causes the lower mileage but it is the wind resistance from that large fairing and windshield that makes the mileage go down from higher speeds. It is generally accepted that any rpm over about 3000 causes fuel mileage to suffer. I believe what is actually at work is the wind resistance is what is killing the mpg after about 70 mph, which is about 3000 rpm.

[Solo So Long]

Riding style is the second biggest factor (overall weight being the first).

Run on the cruise control as much as possible.

Flags suck fuel like punching a hole in the gas tank.

The less wind you feel when riding, the less wind resistance your body is creating. Adjust deflectors accordingly.

Clothing that flaps has significantly more drag than clothing which doesn't. That's why the race guys like smooth leather and plastic.

As much as possible, turn stop-and-go traffic into slow-and-go -- the first MPH costs you as much fuel as the last 10 MPH.

[bellboy40]

That is all good stuff Solo, except that part about cruise control. Cruise is good in flat country but when it turns hilly that cruise control is going to cost you more fuel. It wants to let off the throttle going down grades and then crank it back in going up the other side. If you let it speed up going down hill and gain momentum, that will help take you up over the following hill without using so much fuel. Otherwise, those are all good suggestions.

[Solo So Long]

If you have your cruise control set for the speed limit, going downhill, you're not going to gain a lot of energy anyhow. Then it will smoothly bring in power to get up the other side.

And you can wave at the motorcop with the Pro Laser 4 when you go past him at the bottom of the hill.

[bellboy40]

If you have your cruise control set for the speed limit, going downhill, you're not going to gain a lot of energy anyhow. Then it will smoothly bring in power to get up the other side.

And you can wave at the motorcop with the Pro Laser 4 when you go past him at the bottom of the hill.

That is the problem. It throttles back going downhill and then adds in more throttle on the other side wasting fuel.