GL1200 sucky mpg

4761 Views 35 Replies 20 Participants Last post by Bike...and Dennis, Aug 26, 2009

thedogpirate

Discussion Starter · Aug 14, 2009

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Ok, I have a 84 Interstate that is getting around 24 mpg right now. After hours of research on this I think I need to rebuild my carbs but before I do that I was does anyone have any suggestions? Also I have a slight backfire on deceleration sometimes.

Oh, average speeds are 65-70 mph.

Also was reading about the air cut off valve being a culprit. My question about that is, is it one valve per carb or is it one valve periods

Thanks

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1 - 20 of 36 Posts

G

· #2 · Aug 14, 2009

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Wish i could help but someone will come along soon and tell you all you need to know.
Yes your gas mileage sucks my 1500v gets 40 average.
WELCOME FROM MISSISSIPPI

DaveClifton

· #3 · Aug 14, 2009

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Just my 2 cents worth. I had a 76 GL1000 I bough new that always got 45 to 50 mpg.

I now have a 89 GL1500 and get 40+ mpg. I just replaced the timing belts, plugs and the trigger wheel (4 degree) and it seems that it is even better.

cntryboy1289

· #4 · Aug 14, 2009

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Yes it is just the one slow air cutoff valve.

Have you looked at your plugs lately to see if one or maybe two cylinders are carbon fouled or covered in oil what not? You need to make sure everything else is right before you take the carbs off to rebuild but they could be the problem themselves.

grayglennsr

· #5 · Aug 14, 2009

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Okay Okay I can't keep quiet any longer ....

You're down in Louisiana and I can't resist.

YOU MIGHT BE A ******* IF .... YOUR LOUISIANA GOLDWING BACKFIRES AFTER SUPPER!

Been there... done that .... Ft Polk ...

Bike...and Dennis

· #6 · Aug 15, 2009

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Hi Dogpirate,

Granted, that is pretty poor mileage.

I will occasionally get that kind of mileage if I'm runnig hard. Or crossing Kansas, at the speeds you indicate.

Have you monitored several tanks and that is the average or was it one tank?

I don't think carbs alone can cause the mileage to drop into the twenties. The bike would have to be barely running.

Other causes could be brakes dragging, fuel leak, bike sitting more than it's being ridden, faulty odometer or even improper equations.

Anyway, my advice would be to go on a two, or three-day ride, perhaps with friends, so you can compare miles driven, fuel useetc.

Keep careful records and report back here. If the bike is running on all four, I think we can get you into the high thirties without pulling the carbs.

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deradler1

· #7 · Aug 15, 2009

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My 93 Interstate just got almost 50 mpg on its last tank with a combination of city and highway miles.

smokepole

· #8 · Aug 15, 2009

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my 84 gets 40, think it always did. But I think it used to accelerate better. I was diong 50 today, dropped 2 gears and cranked it open. I'm almost positive it used to wheelie. almost, not something I do on a regular basis, and usually by accident

jwhitmore44

· #9 · Aug 15, 2009

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It's not a Goldwing but it uses CV carbs like a goldwing

My old BMW got terrible millage when I first got it. I overhauled the carbs and found that the diaphragms had holes and the floats didn't seem to be floating enough. After replacing the diaphragms and floats (and giving the carbs a good cleaning) the bike went form 28 to 43 mpg.

thedogpirate

Discussion Starter · #10 · Aug 15, 2009

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Bike...and Dennis wrote:

Hi Dogpirate,

Granted, that is pretty poor mileage.

I will occasionally get that kind of mileage if I'm runnig hard. Or crossing Kansas, at the speeds you indicate.

Have you monitored several tanks and that is the average or was it one tank?

I don't think carbs alone can cause the mileage to drop into the twenties. The bike would have to be barely running.

Other causes could be brakes dragging, fuel leak, bike sitting more than it's being ridden, faulty odometer or even improper equations.

Anyway, my advice would be to go on a two, or three-day ride, perhaps with friends, so you can compare miles driven, fuel useetc.

Keep careful records and report back here. If the bike is running on all four, I think we can get you into the high thirties without pulling the carbs.

This is actually from recorded mileage over the last month. I just divide the number of miles on the trip meter by the number of gallons I put in. I average 120 miles when I put 5 gallons in.

Dusty

· #11 · Aug 15, 2009

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Start off wit a bottel of seafoam in a full tank burn it all out fill up and then check your MPG ang get back to us.

thedogpirate

Discussion Starter · #12 · Aug 15, 2009

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Dusty wrote:

Start off wit a bottel of seafoam in a full tank burn it all out fill up and then check your MPG ang get back to us.

That didn't help at all. That was one of the first things I tried

Dusty

· #13 · Aug 15, 2009

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How about the plugs did you change them ?

thedogpirate

Discussion Starter · #14 · Aug 15, 2009

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Dusty wrote:

How about the plugs did you change them ?

Yes, replaced them two weeks ago and still no change.

William_86

· #15 · Aug 15, 2009

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get your carb rebuild kit here: www.randakks.com it comes with everything you need.

Dusty

· #16 · Aug 15, 2009

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also don't forget to synk them

Maddmongo

· #17 · Aug 16, 2009

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When I had my '84 1200 itwould dip into the lower/ mid 20s on a regular basis if I was getting after it.

I didn't have any symptoms of idle air valve issues (no backfiring on deceleration), but even so I went through my carbs after 20 or 30K and there was nothing wrong with them.

Normal riding netted me low 30s on average. That is a mix of some in town riding with 75mph - 85mph highway runs 30+ miles long one up.

Granted I don't "piddle" around, but I certainly wasn't playing Ninja boy racer either.

The bike was like that from day 1 when it was brand new.

Check your plugs for color and that will give you a good starting point if you think you have a problem.

Just for reference....

My '82 1100 would get mid 30s...maybe 40 once in a while if you drove on egg shells.

My current '99 1500 is gettingmid 30s running 75 mph - 85 mph on the highway.

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johnnymac

· #18 · Aug 16, 2009

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Dogpirate, what kind of exhaust do you have and what condition is it in? Just curious.

Also Welcome from OKLAHOMA!!

johnnymac

· #19 · Aug 16, 2009

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I have also read about other motorcycles that if you have a leak in your exhaust it can suck air and backfire. I guess it could happen on a wing. My buddy has a 2003 Indian that was backfiring, sure enough it had soot where the pipe joined the head. My 1500 had aftermarket loud exhaust. All the guys I met with 1500s were claiming mpg in the 40s. Mine got 32 or 33 with a tailwind. My car got better mpg.

I amalways in the 43 to 45 range with my 1200LTD usually cruising at 75-79 bursts up to 85 (you just cant tell)

Not that anbody rides a GL1500 just for gas mileage

Bike...and Dennis

· #20 · Aug 16, 2009

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Dogpirate,

Look at Mongo's numbers. Are you driving like him? Because those figures are normal! I average 37 or 38 mpg on the highway at 65~70 mph. If I take it up to 75~80 it can drop to33 mpg.That's with the cruise control set on long trips. Around town that drops considerably.

My point is, if you are heavy handed your mileage may not be abnormal. That's why I suggested a trip that would entail 10 orso tanks of gas on the highway. Comparing apple to apples.

And the people who are saying they get 45~50 miles per gallon? Well they drive way more conservatively than most. And it's a fact that most Honda speedometers are optimistic. Some as much as 10 mph. So there is a possibility that a person can get 50 mpg out of his GL, but he may be running a true 50 mph to get it.

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