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81 400 special running lights and throttle issues


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Hi everyone, I'm new to this site, and the street bike world. I was hoping to get a little help for a couple problems I'm having.

This April, I bought an old 81 400 that somebody stopped caring for about 8 years ago. I've taken the time to go over almost everything, with the exceptiption of tearing down the motor. I have it running, and shifting, tuned up, carbs cleaned etc. But one of my problems seems to be the motor speed when pulling in the clutch to shift through the gears.

When the bike is in neutral, the throttle seems to snap right back along with the rpms. When riding though, the rpm's seem to not want to drop right as I'm going through the gears. Anyone know if this is normal to the bikes, or something's wrong?

My other issue is the running lights. They don't work. I'm pretty sure they did when I bought the bike, but now they don't. Turnsignals work normal, headlight and highbeam work when the bike is running, but not when the key is turned on before it starts. My other bike is not this way, but I don't know how the 400 is supposed to be. There aren't any wire connections that seem loose or anything, and I even tried a different bulb.

Any help would be really appreciated.

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Hi everyone, I'm new to this site, and the street bike world. I was hoping to get a little help for a couple problems I'm having.

This April, I bought an old 81 400 that somebody stopped caring for about 8 years ago. I've taken the time to go over almost everything, with the exceptiption of tearing down the motor. I have it running, and shifting, tuned up, carbs cleaned etc. But one of my problems seems to be the motor speed when pulling in the clutch to shift through the gears.

When the bike is in neutral, the throttle seems to snap right back along with the rpms. When riding though, the rpm's seem to not want to drop right as I'm going through the gears. Anyone know if this is normal to the bikes, or something's wrong?

My other issue is the running lights. They don't work. I'm pretty sure they did when I bought the bike, but now they don't. Turnsignals work normal, headlight and highbeam work when the bike is running, but not when the key is turned on before it starts. My other bike is not this way, but I don't know how the 400 is supposed to be. There aren't any wire connections that seem loose or anything, and I even tried a different bulb.

Any help would be really appreciated.

no motor = no running lights

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no motor = no running lights

Thanks for the reply. They don't work while the bike is running either though. But now I know to mess with them while the bike is running.

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Thanks for the reply. They don't work while the bike is running either though. But now I know to mess with them while the bike is running.

If the bulb isn't dead, check the relay in between the Headlight and the battery. Sometimes they do go bad - you can wire the light direct (bypassing the relay) to test.

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Thanks for the reply. They don't work while the bike is running either though. But now I know to mess with them while the bike is running.

Are you talking about the headlight and taillight or about the front signal lights? As far as I know the front lights are turn signals only. I'm looking for the hardware to convert my front signals to running lights, but so far have had no luck. Does the headlight come on when the engine runs? This is normal and as designed if it does, there is a relay under the front of the tank that turns on the headlight when the alternator starts charging.

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Are you talking about the headlight and taillight or about the front signal lights? As far as I know the front lights are turn signals only. I'm looking for the hardware to convert my front signals to running lights, but so far have had no luck. Does the headlight come on when the engine runs? This is normal and as designed if it does, there is a relay under the front of the tank that turns on the headlight when the alternator starts charging.

Thanks for your reply.

I'm talking about the front running lights not working. The turn signals do, but the running lights don't. It seems like all other bikes I see, have running lights. Most don't have rear running lights which I think is silly, but that's a whole different issue I guess.

The headlight does not come on until the engine is running. This surprised me too, but makes sense when you really think about it. Why waste extra battery juice while starting your bike?

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Thanks for your reply.

I'm talking about the front running lights not working. The turn signals do, but the running lights don't. It seems like all other bikes I see, have running lights. Most don't have rear running lights which I think is silly, but that's a whole different issue I guess.

The headlight does not come on until the engine is running. This surprised me too, but makes sense when you really think about it. Why waste extra battery juice while starting your bike?

Pretty sure there isn't running lights on the front, just blinkers, single filament. If I'm wrong, my bike is broken too (wouldn't be surprised).

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Pretty sure there isn't running lights on the front, just blinkers, single filament. If I'm wrong, my bike is broken too (wouldn't be surprised).

hi guys i have a 79 xs400 with no running lights just signals

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hi guys i have a 79 xs400 with no running lights just signals

just switch on your lights before you move off if your that worried!!

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Thanks for your reply.

I'm talking about the front running lights not working. The turn signals do, but the running lights don't. It seems like all other bikes I see, have running lights. Most don't have rear running lights which I think is silly, but that's a whole different issue I guess.

The headlight does not come on until the engine is running. This surprised me too, but makes sense when you really think about it. Why waste extra battery juice while starting your bike?

The XS400 doesn't have running lights. Those lights on the front are just turn signals. Look at the bulbs and sockets, just a single filiment and contact, also just a single hot wire as well. You will need to modify it for running lights, but I have not been able to find replacement sockets to do that with yet.

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Thanks everyone for the replies on the lights!

I can't wait to get this sucker on the road. Now that I know the bike doesn't need running lights, I can get it inspected.

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When the bike is in neutral, the throttle seems to snap right back along with the rpms. When riding though, the rpm's seem to not want to drop right as I'm going through the gears. Anyone know if this is normal to the bikes, or something's wrong?

Just wanted to mention that I cleaned my carbs on my 81 xs400 at least 6 times, and still had a jet that had enough debris in it to stick. The symptoms of the problem I had fits your description perfectly. If I were you, I would pull the carbs and pull all the jets, clean them and then see how it runs...

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Its not quite the right thread, but I don't want to start another - anyone have an idea why the neutral indicator would stay on and not turn off?

crud/swarf making a connection. undo the left sprocket cover and there should be an iory colored plastic thing with 3 countershrunk screws and 1 connection. take this off and clean it.

BTW :offtopic:

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Just wanted to mention that I cleaned my carbs on my 81 xs400 at least 6 times, and still had a jet that had enough debris in it to stick. The symptoms of the problem I had fits your description perfectly. If I were you, I would pull the carbs and pull all the jets, clean them and then see how it runs...

ultrasonics the way, I'll tell yer!!

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Just wanted to mention that I cleaned my carbs on my 81 xs400 at least 6 times, and still had a jet that had enough debris in it to stick. The symptoms of the problem I had fits your description perfectly. If I were you, I would pull the carbs and pull all the jets, clean them and then see how it runs...

Thanks, I'll have to try that this weekend.

Drewpy,

What's ultrasonics?

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Thanks, I'll have to try that this weekend.

Drewpy,

What's ultrasonics?

its a sure fire method of cleaning your carbs using ultrasonic sound waves

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