I have a 1981 yamaha 650 that the battery keeps being drained. Does anyone have any ideas?

Answer 1

Maybe it's your alternator, Does it drain while the bike is off overnight for example or does it not start again after you've been riding it?

Cheeck your battery has water in it, Clean all your plugs and leads, If none of that works you might need a new battery.

Answer 2

YES,I think I do.First,if it is a wet cell battery,make sure all (6) cells are at the proper level,directly in-between the upper and lower level marks on the battery casing,using distilled water only to correct any cells that are low and DO NOT fill above the upper level.Charge the battery until it becomes fully charged,if the battery gets extremely hot,replace it.If it takes a charge,re-install on bike and start.Using a volt meter,check voltage with probes at the battery terminals(probes supplied with meter),at Idle.This reading should be somewhere in the range of12 to 12.9vlts.Then,bring the rpm to around 3000 and recheck volltage at the battery terminals,the voltage should be now in the range of13.9 to as high as 14.4vlts.If it is higher than that,then,you may have a bad regulator/rectifier.If the voltage does not rise as the rpm's goes up,then,you may have a bad stator,which you may be able to replace the brush set,if available.IF everything tests OK,then,check for a brake light staying "ON",as this will drain a battery while you are riding.Note:if a battery is overfilled,the charging system will have difficulty recharging the battery.If it is too low on water,it will not hold a charge.

Answer 3

The early Yamaha SX650 twins were notorious for having weak electrical systems. The alternators didn't start charging at all until the engine was spinning up to around 3000 RPM, so if most of your riding involves moderate speed highway cruising, you're not getting a full charge back into your battery after you drain it on start-up. At least it still has a kick-starter for when the battery won't turn it over. Try running in a lower gear to keep the revs up for a bit after starting.

Your best bet is to just buy a motorcycle battery maintainer and get in the habit of plugging it in when you're finished riding for the day.

Answer 4

Too many possibilities. Assuming you have a good battery, turn everything on the bike off. With charged battery in place, hook up the positive cable first, then touch the negative cable to the negative terminal on the battery and see if it sparks. If it does, you have something wrong in one of the many circuits and will have to start a long process of elimination buy pulling fuses and wires until you get an idea where the short is. One place it could be is the diodes in the alternator. But there are just too many possibilities. A skilled techician would take 30 to 60 minutes to isolate it. A do-it-yourselfer could take all day and still not find it.

'nuff said?

Answer 5

each and every from time to time those have a oil rigidity sensing change this is hooked as much as an hour meter that must be the situation. The sensor would be consistently powered and if it is going undesirable it somewhat is going to act such as you're describing. that's located on the engine with 2 wires to it. attempt taking a try easy and notice in case you would be sure what continues to be powered once you have the biggest off. As yet another submit stated it must be the battery. once you close it off attempt disconnecting the floor twine from the battery and letting it take a seat overnite and notice if it somewhat is going to start up day after right this moment. If it does then the battery is okay. in this mower the starter acts as a generator so look over the wires to work out if there is any obtrusive shorted wires. wish this helps.

Answer 6

This could be several things so I'll give it to you in the order of the steps :
1 Disconnect the battery after a ride
2 see if it starts the next day
a) if it does it's electrical (buy a manual or get a mechanic)
b) if doesn't it's the battery`
3. it does start ( check the manual )
a) check the ignition switch
b) check the stater ( not starter )
c) check the alternator
d) check the wiring harness
d.1. check every connector for corrosion
d.2. look for broken wires
d.3. look for burnt or missing insulation
4. All these fail to fix it
a) install a battery disconnect switch

Bike owner and mechanic since 1972 one of these WILL work!

Answer 7

This is the correct answer:

If your alternator brushes are good then the alternator rotor is bad. First check the brushes for being worn down.These are notorious for wearing down without owners not knowing or checking them. If the brushes are good length then the alternator rotor is probably bad and not charging. This too is notorious for going bad. This is not difficult to replace but just hard to find a rebuilt one without help. I am helping you to save $100s of dollars.

Do not try and buy a rotor from Yamaha- it will be the same age and problems and cost you 3 times as much if they can even get it. See the links for lower cost repair parts.

Answer 8

The most likely culprit is a switch that isnt going all the way. Somewhere in the ignition circuit or the start circuit if it is electric start. It could also be a wire connecting to ground somewhere or even corrosion between two terminals. Try cleaning and seperating wire bundles and terminal connections.

Answer 9

You've got an electrical short in one of your switches or light sockets.
Not bad enough apparently to be noticeable. Feel around the base of your switches after the cycle has been off and in a cool area for a while and see if you find any warm areas.

Answer 10

disconnect the battery after a run. Doesn't start..poor battery..if does it's the charging system..go to a mechanic..