1981 Yamaha xs400 No Power

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gymrat1964 · Mon Jul 02, 2007 3:14 am

Bought an 81 xs400 yesterday that has sat in a garage for the past 20 yrs. I put in a new battery, turned on the ignition and there is no sign of any power. My guess is the voltage regulator, but I am just guessing. Anybody have any input?
Also, is this bike supposed to have electric start? There is a spot that says Start, but the button is missing.

Johnj · #2 Unread post by **Johnj** » Mon Jul 02, 2007 3:32 am

Are you sure the battery is fully charged? Can you put the battery on a charger for a couple of hours? Have you checked the fuses yet? Make sure the ground lead to the battery is connected to the engine.

As far as I can tell your bike has to have an electric starter. I didn't find any pictures with a kick starter.

Find a motorcycle salvage yard in your area and they will have most of the parts you need.

Google can be your friend.

gymrat1964 · Mon Jul 02, 2007 3:35 am

Thanks for the quick reply.
The bike does have a kick starter on it. I did charge the battery after I installed it and checked the fuses. I did not check the ground though, I will have to do that.

Mon Jul 02, 2007 5:11 am

THe 81 xs 400 I used to own had both a kick and an electric start. Definitely go over the electrical system for the bike as it is definitely finicky

gymrat1964 · Mon Jul 02, 2007 6:33 am

Thanks for that info.
Upon further thought the voltage regulator shouldn't cause there to be no power when the battery is charged. The ignition switch could be bad. Any other thoughts of what could cause that?

#6 Unread post by **Sev** » Mon Jul 02, 2007 6:36 am

Check for a loose ground somewhere on the bike. Disconnect the ignition switch and test the resistance across it in all positions with a multimeter.

Look for loose or blown fuses. Is the battery installed the right way around? A backwards battery will blow the main fuse.

You charged the battery After you installed it? That doesn't sound right.

The voltage regulator is part of the charging system, and won't affect the starting of the bike.

thespirit · #7 Unread post by **thespirit** » Mon Jul 02, 2007 7:03 am

If it's been sitting for 20 years, you should probably go over all of the connections and clean them up. They will probably be pretty corroded.

I don't know for sure on your model, but some of them had a small fuse box, but also a main fuse that was separate. Check to make sure that if you have one that is separate, that it's still good.

gymrat1964 · Mon Jul 02, 2007 7:14 am

Yeah the battery instructions said to put it on a trickle charge for best results, even though after adding the acid it should produce current. I will check for loose grounds, I checked the fuse box and they were all good. I will have to hunt for that main fuse, any idea on the location of that?

thespirit · #9 Unread post by **thespirit** » Mon Jul 02, 2007 7:22 am

If you do have the main fuse that is separate, I think it was on the right side behind the side cover. Being an '81, it probably is not separate, but the '79 a older models did have some that were.

Make sure your connections are nice and shiny. If they are not, take some sandpaper to them. The Works bathroom cleaner will work too. Just dip the connector in and let it sit for a few seconds then rinse it off with water. I would start at your battery terminals and work your way forward.

It is also possible that your ignition switch is also corroded on the inside. Older yamaha ignition switches could be taken apart to be cleaned, but I do not know if yours can be. It's something to look into after you cleaned all your contacts.

gymrat1964 · Tue Jul 03, 2007 7:54 am

It was the ground wire. Thanks to everyone for your help.

I have one more question. On the back of the petcock there is a port that points up under the gas tank, looks like for a piece of tubing. Is this supposed to be attached to something? I put gas in the tank and this leaks.