One for the mechanical experts


Information and questions on GL1500 Goldwings (1988-2000)
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One for the mechanical experts

Postby mervk » Fri Feb 28, 2014 4:31 am



Hi all. Anyone know the implications of removing the exhaust cross-over chamber beneath the bike? I have bought the most wonderful 93 1500 Trike, however part of the conversion was to remove the balance chamber and have seperate exhausts for each side. I'm looking for the reason my fuel usage is so lousy. Admittedly, there is a bit more weight to pull, however usage is about 1 liter per 10 kilometers, or roughly 25 mpg (I think).

The bike rolls so easy on the tarmac, and has heaps of power, and the current weight is no more then if I had a pillion on board. Expected somewhere in the mid 30's for milage. Wondering if the change to the exhaust system may have an effect. All comments welcome.

Cheers

Merv


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Re: One for the mechanical experts

Postby themainviking » Fri Feb 28, 2014 7:56 am

Removing the equalization can have a small effect on fuel mileage, but not much. Removal of same can also increase or decrease power, depending on the situation. What it accomplishes is a change to the back pressure that the exhaust creates. All engines require some back pressure, but the average backyard fixit person (most of us) do not have the knowledge to calculate the perfect amount. If removing the equalization created more back pressure for your bike, it would affect both power and fuel economy. A company called Torq Master manufactures an exhaust loop which could just be for your situation. It replaces the factory equalization setup and likely reduces back pressure a small amount. A google search would provide more info on the Torq Master Performance Loop.
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Re: One for the mechanical experts

Postby eklimek » Fri Feb 28, 2014 9:07 am

The cross over pipe is used to redistribute pressure pulses in the exhaust manifold left to right. It is most useful if the firing order does not alternate sides.

The flat 6 Firing order is 1-4-5-2-3-6 and the drawing shows:

1 3 5

2 4 6

<--- Front

In the goldwing it serves more to reduce the sound level than reduce the manifold pressure faced by the open exhaust valve. The slight reduction in efficiency would be noted only with sustained high power. That was not Honda's target market.
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Re: One for the mechanical experts

Postby jhngardner367 » Fri Feb 28, 2014 5:16 pm

Did you re-synchronize/balance your carbs ?
I did this on my '84,and once they were re-synched,my mileage improved.

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Re: One for the mechanical experts

Postby RoadRogue » Fri Feb 28, 2014 9:17 pm

I seem to remember someone talking about the various rubber vacuum lines causing poor gas mileage when then crack and leak, particularily the ones under the rubber heat mat. Your bike/trike is old enough to have these issues. Pay attention to the lines that have a 90 degree bend to them. 8-)
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Re: One for the mechanical experts

Postby mervk » Fri Feb 28, 2014 11:09 pm

Thanks for the tips, guys. The extra noise is now explained by the loss of the muffling effect of the crossover chamber. Bike is quite loud at highway speeds, and it was my intention to fit a couple of short Hot Dog mufflers at the rear. And the carb tune and vacuum line inspection are definately on my to do list.

But until then, I'll carry a 2 gal container in the trunk. Luckily, there is room......

Cheers

Merv
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Re: One for the mechanical experts

Postby 2manywings » Wed Mar 12, 2014 10:53 am

For a trike, the mileage is not too far off. I do a lot of carb work and would definitely suggest a total rebuild. As these 1500s age( and this one is 21 years old now), if they haven't been apart, it's time. The seals, o-rings, hoses and diaphragms deteriorate with time. Almost every 1500 carb rebuild that I've done in the last couple of years (probably 10-12), has also needed new slide diaphragms. Inspect them closely for cracks and pinholes. If your losing vacuum at that point, your performance will suffer greatly. There are also vacuum hoses under the boot that are well known for deteriorating. A complete carb rebuild on a 1500 can run into some serious expense (carb kit and slides alone will run you over $300), so be prepared if you decide to have it done. I only use Randakk carb kits (they're the best on the market), but the slide diaphragms will be a dealer item. This is a very labor intensive job. If you plan on doing this yourself, do your homework!!! You don't want to do this job twice. Ask if your not sure... Good Luck!
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Re: One for the mechanical experts

Postby 2manywings » Wed Mar 12, 2014 11:07 am

Forgot to mention the exhaust. I currently ride an 1800 with torq loop which give a true dual exhaust. It did give a bit more low end torq and added some mileage, but the nice exhaust tones cause me to get on the throttle a bit more than needed. So it's hard to put a number on it.
I recently fitted a pair of Harley Sportster shorty mufflers to a '96 trike that I was going through. They were nice and easy to fit, and gave a mellow tone that was very acceptable at highway speed. They are also a dime a dozen.
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Re: One for the mechanical experts

Postby mervk » Wed Mar 12, 2014 4:36 pm

Thanks 2manywings. Wish you were a little closer - I'd have you look at both the carbs and the sound. I have added a couple of foot long Hotdog mufflers which make it acceptable now, however a 75 mile ride two up yesterday drank 3/4 tank of the dear stuff. So I'll look for a local who is experienced with wing carb systems and have them done. Love riding it though........

Cheers

Merv
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1993 'Black Beauty' 1500 SE and chair.
1993 GL1500 Trike.
+ about 20 bikes from 1914 to current.

Re: One for the mechanical experts

Postby Fatwing Chris » Wed Mar 12, 2014 5:44 pm

Whatever you do don't go by the fuel guage unless someone has calibrated it at some point.You probably still have at least half a tank when it says 1/4.The needle drops pretty quick on these normally,but It will run untill the needle is below the the "E".There's been lots of discussion about the 1500 guages and most of them were like this.I know mine was.I never tried to calibrate it as it really didn't bother me.I knew how far it would go on a tank.


If I'da known it would last this long,I'da taken better care of it.
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