Interesting starting problem

[Sniper]

Well the new bike is going well. I have done the basic strip down to see hwere everything goes and how clean she is ect ect. Anyway, as of late I have been having an interesting problem.

When I ride with my lights off its fine, the bike will start up straight away after I have turned her off. But when I have my lights on, and I turn her off, she won't start at all for 20 or so minutes. It sounds like a flat battery when she trys to start but the thing is if I leave it for 20 mins or more she will start first pop.

Is it battery or charging system?

Cheers guys and gals

[bobsmith]

Sounds a little like combination of both.

I sounds like the charging system is struggling to keep up with all the load and not keeping the battery charged up with the headlight on, while the battery is aged and does not hold its voltage well. Old batteries tend to drop their voltage when they are used and takes a bit of rest time for the voltage to come back up again.

Tell me how much accessory that draw electricity do you have on your bike? Perhaps the current draw of added aftermarket accessories and/or brighter bulbs together exceed the current rating of the alternator...

If it is what I think, getting a new battery will solve the problem only if you don't run it with the lights on time to time to keep the battery charged up.

One way to check it might be to see if you can find the specs for the alternator then add up all the things that's using the electricity on the bike (including lights, accessories, etc...) and see how those values compare, becareful because a lot of the things that use electricity like fuel pump, dashboard, ecu might not be listed.

If you don't have any accessories or brighter bulbs on, it "might" be that the alternator is on the way out, or there is gross resistance in the wiring (due to old wiring or rust, etc...) or a voltage leak somewhere. Or you could ask someone that knows more about bike electrical system than me since my knowledge is primarly based on aviation.

Hope this helps.

[Sniper]

Cheers matey

[bungbung]

Have you got uprated headlight bulbs Sniper?

edit. Bob Smith is on to it.

[Sniper]

I don't think I have bungbung and bob. I'll take them out tonight and see.

[Quasievil]

Best Check is turn engine on and turn lights on, if you throttle the engine and the lights get brighter your charging system is fine, if they do not get brighter charging system is the problem.

easy and quick check

[Sniper]

Thanks Quasi :niceone:

[Postie]

i had a similar problem with my CBR400, so i took the battery out and charged it overnight and its been fine ever since. I was gonna buy a new battery but i didn't need to in the end, its kept a fine charge ever since.

[Sparky Bills]

They are known for the cdi's to crap out.
Get that check out.

[F5 Dave]

The reason the CDIs crap out is that the regulator/rectifiers stop regulating & that kills the battery (boils water out too) & the high voltage can kill the CDI.
Throw a multimeter over the battery & rev it. Any more than 14.5V & you are in trouble. Do this soon. Simple meters are almost free from Dick Smith.

This can also burn out the alternator which means you would get low volts when running with the light on, should have at least 13V running with light on. So if you had to replace/rewind the alt then check it afterwards too.

[Sniper]

Bastard, bugger, blast.

Anyway, chucked a multimeter across the battery last night and got a reading of 14.78- 14.85v. And when I rev it, there in no noticable change. Now Im not know for my mechanical ability and I have learnt that spark plugs are sneaky bastards, but what would be causing such a high voltage to be put out (my guess is regulator) and what would I have to replace and who might have one?

Thanks for your help guys.

[F5 Dave]

Erm, well maybe it isn't kafut. Bikes have been running a little higher voltage, & is higher than I expected (but only by 0.3V), but the dead give away is it is maintained at a constant voltage.

This means the regulator is still working. If it were dead the voltage would soar up to 17 or 20V or so.

[Sniper]

So Im looking at replacing the altinator then?

[Ixion]

Nope. Nothing wrong with the alternator if it can turn out 14+ volts. And recifier is probably OK - since as Mr F5 dave says, cooked recifier would go to 20+ volts when revving.

I reckon your battery's knackered. Just worn out, can't hold a good charge, but recovers a bit when left it sit, they do that sometimes. Either that or you've got some wierd high resistance conncetion, gets worse with heat (cos of higher amps going through it when the lights are on)

Try leaving the lights on for 20 minutes, motor not running. Then start. Should start , might be a bit sluggish on the starter . If it's dead as a dead thing, it's a trip to Ripco for a new battery.

Course, if you had a KICKSTART like a proper bike, you'd have no problems. :devil2:

[Sniper]

Yea, the thing that really boggles my 1 sole brain cell is that the bike won't start immediately after riding with the lights on but after leaving it for 20 + minutes, she will start, but a bit sluggishly.

Ixion, if the lights are on for more a minute, starting her is a real chore. I need to bump start her and no, after the issue with the CR500, I don't like kickstarts

[Ixion]

Yep. Battery's poked. They do that sometimes, recover their charge when y' leave them to sit for a while. Dunno why, and they don't always.

It may be that the charging system design is a bit on the tight side on those bikes (a lot of bikes that era were) and only *just* copes normally with the load with lights on (ie amperage, not voltage). And a brighter than standard headlamp bulb could push it over , so that the battery is slowly draining when running with lights on. Good battery, no problems, it'll last all night anyway, but if the battery's fragile too, it's all too much for it.

Trip to Ripco I reckon. IMHO.

[imdying]

Yep, sounds battery. Take it out and get it load tested by a battery shop... say the one on Barbadoes Lichfield corner?

[Sniper]

Mainland batteries? Yep I think I might pop down to them today. Tonight, valve clearances are going to be checked and then hopefully have her all back together for the weekend.

Thanks for the help guys.

[Sniper]

Just a question, shouldn't the voltage change when I rev the bike?

[F5 Dave]

Ideally not. The alternator should produce enough voltage from low revs & regulator limit that voltage from exceeding too high a voltage.