Loss of power and rear brakes in OD


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richardelsberry
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Motorcycle: 1995 GL1500 SE

Loss of power and rear brakes in OD

Post by richardelsberry »



Hello All,

I purchased a Goldwing 1500 '95 last year and have been experiencing a loss of power when going into OD. When I first got the bike I was able to pull over and sit for a minute, all would be fine and I'd be good for over 300 miles. This year it has gotten much worse. It happens every time I go out and in addition, the rear brakes goes all the way down with no catch. The brakes stay that way the rest of the trip. Then it's fine the next day again. Yesterday, there was a new twist. I pulled my clutch in to coast to the side of the freeway and the gears remained engaged as I down shifted.

One last observation, there has always been a small buzzing sound coming from the dash while this is all happening. Again, after a short stop, the buzzing is gone, the power is back, the clutch works (however, brakes still gone). I also notice a bit of over heating during this but that also goes away after a quick rest.

I've noted that there are no leaks and the master cylinder remains capped off.

I've tried all the great suggestions on this site. Cleaned the gas cap, changed the petcock and fuel filter. I bled the brakes even setting a large brick on the peddle over the weekend. After bleeding, the brakes feel solid until the power loss in OD and then bikes needs to be parked for a while for those to come back.

I've not been able to isolate what's going on. Any thoughts or suggestions would be greatly appreciated.


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Andy Cote
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Re: Loss of power and rear brakes in OD

Post by Andy Cote »

You've been a user here for a couple years but since this is your first post, welcome. Where are you from?

Sounds like you've got a number of issues going on but not sure they are all related.

The transmission is a common five speed. The OD light is just decoration. The engine operates the same in all gears and unless you have a bent shift fork. Really no reason to act differently in fourth or fifth and the shift fork would leave you in a false neutral. It could be something with the ECU not responding, either itself or failing to receive a signal from one of the sensors.

The brakes nor the clutch hydraulics are not connected to electronics or vacuum. They are what they are and really should not change based on how the engine is performing.

There is one thing that I can think of. Heat. If it's really hot under the false tank, the electronics could be affected and the hydraulics could be affected as well. You say you have some high temp gauge readings when this is happening. IIRC there is a heat shield under the intake manifold. Is that there? Improper ignition timing can cause high temps. Does this have an aftermarket timing trigger wheel?
2015 Goldwing, basic black

Previously: GL1200 standard, GL1200 Interstate, GL1500 Goldwing, GL1500 Valkyrie Standard, 2000 Valkyrie Interstate, many other Hondas
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WingAdmin
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Re: Loss of power and rear brakes in OD

Post by WingAdmin »

Next time you have the power loss and hear that buzzing, open your gas cap momentarily and see if the power comes back. Often the gas cap valve gets clogged, causing excessive vacuum in the fuel tank that the fuel pump can't overcome, so the engine bogs down from lack of fuel. Opening the gas cap allows air back into the tank and allows fuel to flow again. The buzzing could be air slowly leaking back into the tank past the clogged valve.
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Andy Cote
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Re: Loss of power and rear brakes in OD

Post by Andy Cote »

Did you ever resolve this?
2015 Goldwing, basic black

Previously: GL1200 standard, GL1200 Interstate, GL1500 Goldwing, GL1500 Valkyrie Standard, 2000 Valkyrie Interstate, many other Hondas
richardelsberry
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Re: Loss of power and rear brakes in OD

Post by richardelsberry »

Hi Andy, Apologies for taking so long to respond back. I didn't check the notify me checkbox so forgot to check back. No I still haven't figured this out.

Thanks for the suggestion WingAdmin. Yes I tried unscrewing the gas cap last time that happened but it didn't make a difference. It still remained stalling once I opened it.

The brakes nor the clutch hydraulics are not connected to electronics or vacuum. They are what they are and really should not change based on how the engine is performing.
There is one thing that I can think of. Heat. If it's really hot under the false tank, the electronics could be affected and the hydraulics could be affected as well. You say you have some high temp gauge readings when this is happening. IIRC there is a heat shield under the intake manifold. Is that there? Improper ignition timing can cause high temps. Does this have an aftermarket timing trigger wheel?


This is an interesting comment. I'm been told several times that brakes are a separate system than the electronics/vacuum which makes sense but regardless, it is consistent, each time there is a temporary loss of power the rear brakes go out and I drive home to let it sit for a while and all is good. I never thought about heat affecting both systems. Like I mentioned, the heat gauge does go up but only slightly. Not enough to have to pull over to cool down. I drove 400 miles and a quick stop on the side of the road and the heat gauge was back to normal.

I don't know about the timing trigger wheel I'm getting close to taking it into a mechanic. If so, I'll bring that up and mention heat under the false tank.

By the way, what is a false tank?

I'll update my post when I get this figured out.
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Re: Loss of power and rear brakes in OD

Post by WingAdmin »

If you have moisture in your brake lines, and you get enough heat and pressure (pressure creates more heat), the water can boil - and steam is very compressible, meaning no brake pressure. Once it cools off and condenses back to (non-compressible water), your brakes would come back.

The rear brake system does have a brake line that routes right along the engine on its way to the front wheel, so this scenario is not outside the realm of possibility:

GL1500 Brake Line Routing
GL1500 Brake Line Routing

richardelsberry
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Re: Loss of power and rear brakes in OD

Post by richardelsberry »

Thanks WingAdmin. That's an interesting point. I've never done it before but it doesn't seem like it would be that hard to totally flush the rear brake line. I replaced the bleeder valves with the ones I saw recommended by other members here to make it easier for one person bleeding. I forget the name but they were easy to install. I could run a hose off the back line and pump until the reservoir is emptied a few times.
gford
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Re: Loss of power and rear brakes in OD

Post by gford »

The brakes are two separate systems. The front right caliper is controlled by the left lever. The rear rotor and front left brake are linked and are controlled by the foot brake. When bleeding the rear brakes do the front left caliper first followed by the rear caliper.
richardelsberry
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Re: Loss of power and rear brakes in OD

Post by richardelsberry »

Thanks Gford. In fact, like WingAdmin's diagram showed. If it is water in the lines, it would be the line going to the front brakes. So I'll do those first and follow up with the rear just to be complete.
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Re: Loss of power and rear brakes in OD

Post by gford »

gford wrote: Tue Oct 05, 2021 4:46 pm The brakes are two separate systems. The front right caliper is controlled by the left lever. The rear rotor and front left brake are linked and are controlled by the foot brake. When bleeding the rear brakes do the front left caliper first followed by the rear caliper.
Correction, the right front caliper is controlled by the right hand lever.
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Re: Loss of power and rear brakes in OD

Post by WingAdmin »

I think you have two separate issues - one is the brakes, and one is the electrical. Normally when you have weird, unrelated electrical issues like that, it's caused by a bad ground, and I suspect that is the case here.

Have you had a chance to bleed your brakes?
jcwing
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Re: Loss of power and rear brakes in OD

Post by jcwing »

A loss of power followed by loss of pressure in rear brake. Sounds like a brake hose has failed internally and is trapping fluid; brake heats up, fluid expands and brake self applies. All's well once it cools down. Take the necessary tools with you, next time it happens pull over & put the bike on centerstand see if the rear wheel is hard to turn. If it is, immediately open the rear caliper bleeder just a little. If this is the problem, fluid will shoot out by itself, then wheel will be free until brake heats up again.
Never had this on my Wing but my CBR 1000f did this when hoses were old.
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Re: Loss of power and rear brakes in OD

Post by the_big_h »

Even easier check, no tools required:
Avoiding using the rear brake, go for a ride. After 10 or 20 miles, stop (without using the rear brake), and check the brake rotor temperature. Since you haven't used the rear brake, the rear rotor and the left front rotor should be cool to the touch. (Careful, if the brakes are your problem, they might be smoking hot!).
If they are OK at that point, then when you experience your loss of power, check them again. If both are hot, there is a problem with the rear master cylinder (one of the ports clogged). If only one is hot, there is a problem with that caliper.

Perhaps you could expand a bit on what you mean by "loss of power" - is it a complete loss of power (ie you have no choice, you're coming to a complete stop), or will it just not maintain speed? If you stop in this condition, will it still idle OK?
97serider
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Re: Loss of power and rear brakes in OD

Post by 97serider »

Perhaps the loss of power that's being felt is the rear brake engaging which would cause the bike to struggle to maintain speed especially in 5th gear. Just a thought.
body
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Re: Loss of power and rear brakes in OD

Post by body »

About your lost of power. Im sure its your carb heat riser switch not working into your air box. Or the heat tube is disconect. Read about carb icing on wikipedia. Ice Building into carbs venturi. Going worst with high Dew point days. Sorry for my english.
richardelsberry
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Re: Loss of power and rear brakes in OD

Post by richardelsberry »

About your lost of power. Im sure its your carb heat riser switch not working into your air box. Or the heat tube is disconect. Read about carb icing on wikipedia. Ice Building into carbs venturi. Going worst with high Dew point days. Sorry for my english
Thanks for this information. I had never heard of carb icing before. It was interesting to research wiki and other sites. I have a water cooled system which is supposed to be less prone but not completely. I usually get a buzzing sound as well when this happens that seems to come from just below the windshield. I wonder if that would be the result of the constricted air flow from the ice buildup. I can't believe that I didn't try adjusting the choke to see if that would compensate for carb icing. Looks like we will be getting snow here in Minnesota so I may not be able to test this until next spring. Thanks for the suggestion though.
richardelsberry
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Re: Loss of power and rear brakes in OD

Post by richardelsberry »

Even easier check, no tools required:
Avoiding using the rear brake, go for a ride. After 10 or 20 miles, stop (without using the rear brake), and check the brake rotor temperature. Since you haven't used the rear brake, the rear rotor and the left front rotor should be cool to the touch. (Careful, if the brakes are your problem, they might be smoking hot!).
If they are OK at that point, then when you experience your loss of power, check them again. If both are hot, there is a problem with the rear master cylinder (one of the ports clogged). If only one is hot, there is a problem with that caliper.

Perhaps you could expand a bit on what you mean by "loss of power" - is it a complete loss of power (ie you have no choice, you're coming to a complete stop), or will it just not maintain speed? If you stop in this condition, will it still idle OK?
Yes, I guess I was a bit vague. By loss of power I mean that I'm cruising along on the interstate and I start to realize that when attempting to speed up there is no power. The motor is still running but I'm now loosing speed. There is a buzzing sound from under the windshield. I don't have to shut the motor off to recover. Some times I pull off to the side, put it in first and I'm off again. All normal, except no rear brake. Some times it resumes power before coming to a complete stop. Great suggestion. I'll have to wait until the weather improves to give it a try.


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