GL1500 Bad Fuel Economy (25-30MPG)

[cbibler]

I recently purchased a 2000 GL1500 SE and I've been doing regular maintenance to get it restored. I thought I got about everything done and started riding it but I soon realized the fuel economy right now is pretty bad. I'm currently getting 25-30 miles per gallon. I do know the owner said that they've never messed with the carbs because they've never given him any issues. I've looked at a couple different posts already but I've seen a some different things on what to do. I was wondering if anyone knew something like an order of things to check and troubleshoot first. Right now it fires up pretty easily and doesn't need the choke on a warm, sunny day. There is a little bit of variation when at idle but not much.

Things I've done to it:
-Idle adjusted
-Petcock rebuild (It was leaking when I purchased it)
-Final drive oil change
-Oil and filter change
-Coolant change
-Spark Plug change
-Timing belts replaced

I have not changed the air filter because it was done less than 10k ago but it's also been many years since then so I'm starting to think that'll be necessary. I've seen some people say that has to do with it but some other people also disagree with that. I'm also a little worried the timing belts are off because I heard that'll effect the fuel economy but I was extremely careful and it also seems to run fine other than the fuel consumption. Just another FYI I live at an elevation of 4,300 feet.

[Rambozo]

Is this around town riding or highway?

[cbibler]

A bit of a mix. I'd say 50/50 mix where I only go 70mph for about 5 minutes at a time.

[Rambozo]

I would say don't worry about it, until you get some more miles on it. Maybe run a can of Seafoam or two through the fuel system. While my 1500 does great on the highway, around town and small trips my mileage is like yours. These bikes are not known for mileage. At your altitude you are probably jetted a little rich, too. How do the plugs look?

[ct1500]

The 1500 has altitude compensation via the Air Jet Controllers for mixture settings. The slight surge at idle is usually a dead give-away of a lean running condition. 99.9% of the time it is a carburetor problem if no one has had their hands in there before doing fixes/improvements and screwed other things up.

[offcenter]

I would say don't worry about it, until you get some more miles on it. Maybe run a can of Seafoam or two through the fuel system. While my 1500 does great on the highway, around town and small trips my mileage is like yours. These bikes are not known for mileage. At your altitude you are probably jetted a little rich, too. How do the plugs look?

One more vote for Seafoam. When I got my 1500, it wouldn't idle well at all. A couple of cans of Seafoam later and all was well again. I've been getting a steady 42 miles to gallon for the four years I've owned the bike.
Do the cheap stuff first. Seafoam is cheap compared to parts and labor of taking things all apart.
And once you get the bike running right, ride it regularly. Don't let it sit. These bikes need to be driven.

[cbibler]

I would say don't worry about it, until you get some more miles on it. Maybe run a can of Seafoam or two through the fuel system. While my 1500 does great on the highway, around town and small trips my mileage is like yours. These bikes are not known for mileage. At your altitude you are probably jetted a little rich, too. How do the plugs look?

When I changed the old plugs they were a little black, but nothing extreme. I'll see if I didn't throw them out and take a look at them and maybe look at the new ones too but they've only been in for a week or so. I'm surprised, most people say mid 30's to 40mph but I am doing a lot of around town riding.

[cbibler]

The 1500 has altitude compensation via the Air Jet Controllers for mixture settings. The slight surge at idle is usually a dead give-away of a lean running condition. 99.9% of the time it is a carburetor problem if no one has had their hands in there before doing fixes/improvements and screwed other things up.

I might see if I can get a video of it next weekend too to see if its out of the ordinary. I'm going to try some small fixes and see what happens.

[cbibler]

I would say don't worry about it, until you get some more miles on it. Maybe run a can of Seafoam or two through the fuel system. While my 1500 does great on the highway, around town and small trips my mileage is like yours. These bikes are not known for mileage. At your altitude you are probably jetted a little rich, too. How do the plugs look?

One more vote for Seafoam. When I got my 1500, it wouldn't idle well at all. A couple of cans of Seafoam later and all was well again. I've been getting a steady 42 miles to gallon for the four years I've owned the bike.
Do the cheap stuff first. Seafoam is cheap compared to parts and labor of taking things all apart.
And once you get the bike running right, ride it regularly. Don't let it sit. These bikes need to be driven.

I agree and I'll try some seafoam. When you used it what did you do? Just put it into your gas tank or also put some straight into your intake after you removed your air filter? I've seen a couple different things on what you do with the seafoam. The only thing is I've just changed the oil and I've seen some things that say you'll have to change the oil afterwards. I also bought a new air filter and a kit to sync the carbs. If those don't work I might eventually take it to a professional. I don' like to mess with carbs too much. I'll have to post updates for sure.

[AZgl1800]

I bought a '98SE in 2006 that had been sitting for a year, maybe two?

it was in Primo Condition appearance wise...

but the carbs were in ill health.

I poured a can of Sea Foam in the gas tank, left it on the Center Stand, and it idled for more than an hour.
I repeated that every night for a week, the intent is to pull the rich Sea Foam thru the Idle Circuits.

Once you touch that throttle or move the 'choke' lever, those are bypassed.

Flew down to Tampa, FL to buy it, over the next 3 weeks, I put 3,000 miles on it via Houston, Corpus Christi, El Paso then home to Phoenix AZ

it was running smooth as a kitten can purr by the time I got home.

MPG?
it never got more than 33 mph Average over a Year's Time,
that is to work and back a 16 mile trip into Phoenix, then 16 back to home.
several long trips,

I have a Spreadsheet you are welcome to, I recorded every fillup faithfully for a year, plus.

[Solo So Long]

Here's another vote for Seafoam.

I like the letting-it-idle trick, but don't leave it alone while you do that -- if you have any issues with cooling, you want to be there to shut it down before you history the engine. Watch the temp for the first 5 minutes, then every 5 minutes or so after that.

[WingAdmin]

Definitely at least inspect the air filter, if not replace it - a clogged air filter will enrichen the mixture and definitely cause terrible fuel mileage.

[GoldWing808]

I’ve been using Fuelly faithfully since I owned my 1100, and my average since 10/31/13 is sitting at 33.7 MPG. My best ever was 2-up actually, 44.7 MPG in far eastern Maine (I know exactly where I was). I only rarely hit the 200 mile mark on one tank. I have done all the maintenance and had a troublesome vacuum leak in the carbs fixed….new plugs, et alia. The problem I have is the bike was built in March 1988 when the speed limit was, what, 55-65 MPH? It’s 75-80 in Wisconsin now, and it just drinks fuel. So I have to accept the 29.7 I got from da UP around through Indiana, Illinois and into Wisconsin.

I just bought a 2019 and haven’t ridden it, but according to Fuelly the average is 40. We shall find out.

[Clarencechapman]

I'm surprised that a vacuum leak wasnt mentioned more as a cause. Both you and the gentleman who rode 3000 miles plus could have the same problem. The bike runs for the most part just fine but the terrible gas milage is a symptom of a leak. My brother went from 40-45 mpg to about 25 over the course of a few weeks. Ended up selling the bike and never found it. I would suggest a that a good mech can test your vac system and find any leak that its there. I was told and shown a vac tube under the left side cover that is notorious for cracking and I could see why. It bends around in a "C" shape. and it sits right on top of the head so it gets a lot of heat. Good luck

[gk1219]

Brakes tend to stick on old bikes.

[cbibler]

I've done a couple of things to it to try and help the fuel economy but I haven't been able to ride much at all due to weather. I'll post an update with all the details once I'm able to ride enough to get more gas.

[okie2ee]

I've had my 93 GL1500 trike with Tulsa tall windshield for several years now and I have never gotten more that 27 MPG........typically runs around 24 - 25 MPG and I ride at the limit and above............mainly short trips around town with a few long trips thrown in each year............long trips are same mileage............bike runs fine and plugs look good................the vacuum leak theory is something that I haven't looked into but appears to be worth a check...........my previous ride was a Yamaha Vmax so fuel economy was never a factor in my riding

[fern4127]

I have a '95 1500 SE that used to do pretty good on gas. I put a Voyager kit on it, which as expected, dropped my mileage a just a little. Parked it for the winter in NW Ohio as always, after putting Stabil in the tank and running it to get through the entire fuel system. Started fine in the spring and ran great, but mileage dropped about 5mpg. Now, with a full Roadsmith trike kit, doesn't matter how new the plugs and air filter are, the mileage is never above 30 and that is keeping the speed about 60 mph and my RPMs under 3K. Running 70-72 mph pushes the tach to 3500 rpm and mileage in the basement. The rear end gear on the Roadsmith kit upped my rpm's about 200-250, so I'm sure that accounts for some of mileage loss. When I pull the plugs, they are almost colorless. Near as I can tell, it runs just fine, seems to have plenty of power for a 1500, but has been a mystery ever since. Was hoping when I did the belts that I would find a tooth one notch off on the timing, but the timing marks were spot on when I did the belts at about 89K miles. Glad when I triked it I got the auxiliary fuel tank. If I run it weekly, it will start right up, but if it sits for 3 weeks, even with the battery coming straight off the charger (battery is not weak), it will crank for a while before it will start.

[honesttobob]

My 89 Goldwing with 102k miles runs mid30's in town, and high 30's at 65 mph. Running 75-80 takes the mileage down to 34. Recently I got Pulstar plugs for the bike, and my 04 Honda CRV. The plugs are in the car, and my first tank with 2/3's highway driving yielded a 3 mph improvement! It was never over 27mpg. The second tank with the same 240 highway run, is looking like a repeat. The weather has not been cooperative to ride the Goldwing with the Pulstar plugs yet. I am optimistic of a improvement there as well.

[blupupher]

Mileage is really hard to quantify.
There are so many variables that can change the mileage from one tank to another that it makes it hard at times to know what is going on.
I have gotten as high as 37.2 mpg and as low as 17.37 mpg.
My overall average (after 89 fill ups and almost 10,000 miles) is 29.3 mpg.

I track my mileage on Fuelly.com

Here are my last 21 fill ups (you can see them all if you click on the pic above)

I tend to like the go stick, and accelerate hard, which really hurts mileage.
The 17.37 mpg tank was over 3 weeks of nothing but to and from work riding (3 miles, speeds between 30 and 55 mph).
The 37.2 was all highway going about 60-65 mph.

Altitude, hills, speed, road conditions, traffic all make a difference in mileage, as well as just how well the bike is running.
Fuel also can make a difference. E10 tends to give me 2-3 less mpg than ethanol free (from my limited testing, but again, hard to get exact numbers since my riding varies so much), but E0 is not readily available near me, and is $1 more a gallon for it when I can find it, so not worth it for me.

[cbibler]

Mileage is really hard to quantify.
There are so many variables that can change the mileage from one tank to another that it makes it hard at times to know what is going on.
I have gotten as high as 37.2 mpg and as low as 17.37 mpg.
My overall average (after 89 fill ups and almost 10,000 miles) is 29.3 mpg.

I track my mileage on Fuelly.com

1011981.png

Here are my last 21 fill ups (you can see them all if you click on the pic above)
fuel.JPG

I tend to like the go stick, and accelerate hard, which really hurts mileage.
The 17.37 mpg tank was over 3 weeks of nothing but to and from work riding (3 miles, speeds between 30 and 55 mph).
The 37.2 was all highway going about 60-65 mph.

Altitude, hills, speed, road conditions, traffic all make a difference in mileage, as well as just how well the bike is running.
Fuel also can make a difference. E10 tends to give me 2-3 less mpg than ethanol free (from my limited testing, but again, hard to get exact numbers since my riding varies so much), but E0 is not readily available near me, and is $1 more a gallon for it when I can find it, so not worth it for me.

That's super helpful info, good to see that it's not just me. Thank you for that and I think I'll start tracking mine like that too.

[Solo So Long]

E10 tends to give me 2-3 less mpg than ethanol free (from my limited testing, but again, hard to get exact numbers since my riding varies so much), but E0 is not readily available near me, and is $1 more a gallon for it when I can find it, so not worth it for me.

There are tricks for drawing the ethanol out of gas, but for as little gas as we use for fill-up, it's not really worth the effort.

[blupupher]

E10 tends to give me 2-3 less mpg than ethanol free (from my limited testing, but again, hard to get exact numbers since my riding varies so much), but E0 is not readily available near me, and is $1 more a gallon for it when I can find it, so not worth it for me.

There are tricks for drawing the ethanol out of gas, but for as little gas as we use for fill-up, it's not really worth the effort.

Yeah, I have seen that, just get a big container with a drain on the bottom and mix the e-10 with water (I have heard 10/1 of fuel to water), shake it up, and then let it sit to separate, then drain off the water/ethanol from the bottom.
Like you said, not really worth it to me, plus when you remove the ethanol, you also drop the octane rating, so you really need to use at least mid grade if not premium (or add an octane booster) to meet the minimum 87 octane requirement after the ethanol is removed, so that negates almost any savings by removing the ethanol vs just buying e-0

[in2it]

I'm surprised that a vacuum leak wasnt mentioned more as a cause. Both you and the gentleman who rode 3000 miles plus could have the same problem. The bike runs for the most part just fine but the terrible gas milage is a symptom of a leak. My brother went from 40-45 mpg to about 25 over the course of a few weeks. Ended up selling the bike and never found it. I would suggest a that a good mech can test your vac system and find any leak that its there. I was told and shown a vac tube under the left side cover that is notorious for cracking and I could see why. It bends around in a "C" shape. and it sits right on top of the head so it gets a lot of heat. Good luck

Here is a picture of the vacuum line on the left side, under the rubber mat that is a line to look at for leaks

[hondadude79]

Hi all!
I have a link here to the specs for the gl1500 98-2000 models. The fuel economy is at normal range. I get 31 mpg at best ridding around 60 miles per hour on my 98' SE. https://www.motorcyclespecs.co.za/model ... 00_98.html
You get much better fuel economy from a 1800 so I'm thinking of trading up to one.

Ride on !!