RPM is high in all gears


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paseandoconhonda
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RPM is high in all gears

Post by paseandoconhonda »



Hello! It is my first GL 1500 and it is from 1988. The motorcycle already had that problem the same day I picked it up from the store, and it was gone just a few miles from there. Then I did a 4000 mile trip traveling at 75 MPH and 3500 RPM, normal. When he returned, suddenly, the problem again. It happens that the idle speed does not go below 1400 and the rpm increases in all gears. Driving on the highway at 65 MPH it is at 4500 RPM. At first I suspected the clutch and disassembled and cleaned the slave cylinder, which was a disaster and the job came in handy, but it didn't solve it. The strangest thing is that, as seen in the video, in minute 1, the RPM drops by itself from 1200 to 800, solving the problem. You can also see before how the motorcycle came with high RPM and after that traffic light where it stopped, the RPM is normal. Any ideas? I leave the Youtube link. thank you so much.



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Claudio de Argentina.


At night and at 100 it is not noticeable.
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Rambozo
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Re: RPM is high in all gears

Post by Rambozo »

Clutch slipping. Return hole in clutch master cylinder, might be plugged.
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paseandoconhonda
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Re: RPM is high in all gears

Post by paseandoconhonda »

I already disassembled and completely cleaned that piece. Remember that the problem comes and goes.
At night and at 100 it is not noticeable.
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MaineStreet
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Re: RPM is high in all gears

Post by MaineStreet »

Vacuum leak can cause high and/or surging idle.
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paseandoconhonda
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Re: RPM is high in all gears

Post by paseandoconhonda »

And also that in each gear the RPM goes very high? As if the clutch were slipping, both things happen at the same time.
At night and at 100 it is not noticeable.
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MaineStreet
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Re: RPM is high in all gears

Post by MaineStreet »

I see the tachometer rpms going up and down in the video. It jumps pretty quickly. Do you hear the engine speed change when rpm needle jumps?
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paseandoconhonda
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Re: RPM is high in all gears

Post by paseandoconhonda »

You don't feel anything, you just see the rpm go up. In the video you can see that in minute 1, while stopped, the RPM drops by itself from 1200 to 800 and from then on they are normal, they do not exceed 3000 in all gears. It stayed that way and now it's back. Thanks for your time
At night and at 100 it is not noticeable.
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Re: RPM is high in all gears

Post by WingAdmin »

Listening to the engine, you can absolutely tell that the RPM it is turning is nowhere near what is being indicated on the tach. So something is going wrong with either the signal to the tach, or the tach itself.

The signal to the tach is just taken from the ECM. So either something is happening to the signal on its way to the tach, or the tach itself is bad. Is the problem happening or going away when you go over a bump? If so, I would suspect the wiring from the ECM, or the ground from the tach.

If it is pretty random, then I'd have a look at the tach itself.

GL1500 Tach Circuit
GL1500 Tach Circuit

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paseandoconhonda
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Re: RPM is high in all gears

Post by paseandoconhonda »

Excellent thank you very much. It doesn't happen often, in fact it "fixed" itself by stopping at a traffic light, as seen in the video. The RPM dropped by itself from 1200 to 800 and from then on, for almost a month and 4000 miles it ran fine. Then he just came back. These days I will take the time to disassemble and review.
At night and at 100 it is not noticeable.
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Re: RPM is high in all gears

Post by richlilja@gmail.com »

Hello,
First of all, it does sound like the bike has not been used very often and therefore it has a build up of varnish. You would benefit greatly by adding carb cleaner to the gas tank to remove this old gas /varnish eventually as you drive. The idle is simply adjusted with no tools. Open the gas cover and find the small knurled knob next the right side top of the gas filler, give this knob a small turn right or left with your fingers as the motor is running, the motor speed will adjust accordingly you can look at the tachometer to adjust it to roughly 800rpm's. Good Luck!!
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paseandoconhonda
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Re: RPM is high in all gears

Post by paseandoconhonda »

Thank you very much for your comment, but the problem is strange because if I regulate the RPM below 1000, the engine turns off. Not only that, after the problem solved itself,, as seen in the video, I made a trip of 4000 miles consuming about 34 GPM, that tells me that the carburetion is fine. Now that the problem has returned on its own, the idle is at 1400 and the RPM is skyrocketing in all gears. I don't even need choke to start the engine. What's strange? that the problem come and go on its own. I would like, rather than knowing what the cause is, to rule out those that are not.


At night and at 100 it is not noticeable.
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