Motorcycle electrical problem?

My bike wouldn’t start the other day. I guessed I had inadvertantly turned the switch to the “park” position, which leaves the brake light on, instead of “lock”. I started it using booster cables today and it ran fine… until I removed the cable. Then it died. I tried several more times, but it would only run if A) the booster cables were attached, or B) if the revs were relatively high. Obviously I would not be able to start it if I let it drop to idle and die, and if I didn’t have a boost.

What’s the problem? Do I need a new battery? Or is it something bad?

The battery. Probably a shorted cell. If it will run at higher revs, then your charging system is more than likely in tact. I could be that the battery is just that dead, and it needs to charge up a bit, but I wouldnt count on it. Motorcycle batteries dont deal with being run all the way down very well.

Motorcycle alternators typically put out pathetically low amounts of current at idle rpm, in fact many won’t even charge the battery if you just leave them running at idle. If your battery is real and truly dead, you’d get the symptoms you describe. What you need to do is get the bike started and then take it on a little ride (that shouldn’t take much arm twisting, should it?) If the battery is still okay, this should charge it. But if, after riding for 30 minutes or so you come back home and the bike won’t start, then yes you’ll need a new battery. On this ride, try not to let the engine idle for any significant period of time, instead keep the rpm’s up and get a good charge into the battery.

Now the trick is how to keep the engine running while you replace any covers/seat, etc. that you had to remove to get to the battery. I suggest a second person to hold the throttle.

Good luck! I’ve dealt with many dead and seemingly-dead batteries over my riding and racing “careers”.

I don’t know guys, sounds like something else may be wrong here. You don’t need a battery to run a bike once it’s going (I’ve ridden a thousand kilometres with a battery terminal snapped off - I just couldn’t let the engine stop, or when I did I had to push start it). The bike shouldn’t be dying when you take the jumper cables off unless your idle is too low or the engine hasn’t warmed up properly.

I’d do what ski suggested and take it for a long ride. If it’s working properly after that - no problems. If it’s not, then you need to look at any other possible problems.

If it’s still not working I’d put an ammeter across your battery to check if that is really the problem. If you don’t know how to do this yourself, you can call out the AutoClub and they’ll do it for you. Alternatively the autoelectrician at the battery shop will do it for free but don’t forget that they have an interest in selling you a battery.

If there’s no problem with the battery you have to start looking at alternators, regulators, solenoids etc. For that I’d go to the auto-electrician - motorcycle electrickery is my least favourite pastime.

Well, I used to specialize in m/c electrics, back when I was motorcyle wrench. The thing is, if the battery is completely dead, or has a shorted cell, at idle, the alternator/generator is not capable of putting out enough juice to charge the battery, and run the bike. Now, if you disconnect the battery, it might run ok. It also might fry the charging system. Not a good plan, unless you know the specific bike. I have found that once a bike battery goes completely down like this,unless its fairly new it often better to just replace it. When you figure a battery at sams is about 20 bucks, its cheap insurance. ButI’m kinda paranoid about getting stuck on the side of the road. My harley just a little heavy to push.

I’ve done this and it turned out that the battery was almost dry, possibly the recharging from totally dead was to blame.

Filling up the battery worked but it never seemed to start as well as it did, until I repelaced it.

All you can do is check the electrolyte level. charge the battery up on a charger unit and hope, or forget that and just buy the new battery you likely need anyway.

Thanks guys. I guess I’ll call the Yamaha shop and see about getting a battery.

Oh no! Don’t get one from the dealer if you can avoid it or unless you have a good deal going with the dealer. You can buy motorcycle batteries at (some) Walmarts, K-marts, Autozone, etc., and it will most likely be cheaper than the dealer.

Did you try the “ride it for a while” solution?

I put a new battery in last night. When I turned the switch the lights came on. I pushed the starter and it started right up.

Good deal…Glad it worked.

Sack. Twisted the switch today, and no lights. I have an electrical leak somewhere. I have to get the thing into the shop. :frowning:

Look carefully at the wiring loom, something may have rubbed the insulation away.
Good place to start is around the headstock since all the wires crowd in around there.

I used to have an old ‘74 RD 350, little rocket it was, but one day the poor old girl started to run like a bag of the proverbial. New plugs (don’t buy the wrong ones either, make a terrible hole in the top of your pistons) didn’t last very long, blew fuses like nuthin’ on earth and got the occasional “burnt plastic” aroma. After a coupla months of suzuki riders laughing hysterically at me (while idling like i was in the throws of a fit) at traffic lights, I went problem solving. Turns out that the battery was shorting out on the seat base (and no, i’m only 80 kg’s). I lowered the battery case about 1 inch and yeehaa! I was off chasing down V8 fords again. I don’t think this is your problem though, but your on the right track about a short in the wiring somewhere, why do you think most m/cycle mechs are bald. :slight_smile: