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Post subject: RD250 Electrical Problem
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dufflove What's an RD? Joined: 09 Jun 2008 Total posts: 3 |
Just picked up a '73 RD250 and it has some sort of charging problem. Bike starts and runs OK but dies if you turn on the headlight. Turn signals don't work, but that could be unrelated.
My first thought is to check all connections. Anyone have a better idea or tips?
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Posted: Mon Jun 09, 2008 9:33 am
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spooky Daily Burner Joined: 23 Jun 2006 Total posts: 108 Location: antwerpen |
Do you have a new battery ?
if yes then check your rectifier - regulator ......on the bike !
how : put a multimeter on the battery ......bike running @ idle ( all lights of )....you should measure about 13 volt
next step = rise rpm to 5000-6000 rpm ....measure again
should rise again a little 14-15 volt and no more ( loading circuit = OK)
if it does nt rise ......rectifier is shot
if it rise above 15 volt regulator is shot
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Posted: Mon Jun 09, 2008 3:21 pm
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Thrasherg Powerband Master Joined: 18 May 2007 Total posts: 722 Location: Austin, Texas |
Spooky's analysis is a bit simplistic, but he has the right idea. Measure the voltage as he suggest and tell us the results. It could be a bad regulator or a dead alternator.. Once we hear the results we can help you further.
Has the wiring been attacked? Could there be a short circuit in the headlight wiring?
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Posted: Mon Jun 09, 2008 3:23 pm
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zigcoorsDaily Burner Joined: 04 Aug 2003 Total posts: 162 Location: Derby, UK |
How good is the battery? Points model RD's need to have a good battery to run / work properly.
I'd sugest doing the tests as above - and if you have any doubts about the battery replace it.
Check the loom to frame earth lead too - not sure exactly where it is on the early bikes - the later 400's are earthed on the coil or horn bracket.
Ian
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Posted: Mon Jun 09, 2008 5:43 pm
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| dufflove What's an RD? Joined: 09 Jun 2008 Total posts: 3 |
| spooky wrote: |
Do you have a new battery ?
if yes then check your rectifier - regulator ......on the bike !
how : put a multimeter on the battery ......bike running @ idle ( all lights of )....you should measure about 13 volt
next step = rise rpm to 5000-6000 rpm ....measure again
should rise again a little 14-15 volt and no more ( loading circuit = OK)
if it does nt rise ......rectifier is shot
if it rise above 15 volt regulator is shot |
I'm new to all of this so please tell me if I'm doing something wrong. Voltages were measured by connecting the multimeter to both terminals of the battery.
Battery is new. I measure 10.4V on battery with the bike off. Just under 10V at idle and about the same, maybe a little less at higher RPMs. Rectifier?
Another clue is that I had the bike connected to a trickle charger overnight and it stayed on full charge mode the entire time.
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Posted: Mon Jun 09, 2008 11:56 pm
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| p51bombay Joined: 23 Jan 2004 Total posts: 9872 |
If the battery is NEW and reading 10V at rest then its either a shite battery or wasn't charged properly upon activation (initial fill with acid) When charging a new battery a trickle charger won't make it, you need a higher amp one for its first charge, after that you can maintain it with a trickle charger. That said you should still see a rise in voltage when reving the bike. More likely the stator is at fault than the regulator IMO. Has your meter got an AC voltage range? If so you can measure the output of the alternator directly but will need some jumpers as ACV must be measured inline.
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Posted: Tue Jun 10, 2008 12:40 am
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| dufflove What's an RD? Joined: 09 Jun 2008 Total posts: 3 |
| p51bombay wrote: |
| If the battery is NEW and reading 10V at rest then its either a shite battery or wasn't charged properly upon activation (initial fill with acid) When charging a new battery a trickle charger won't make it, you need a higher amp one for its first charge, after that you can maintain it with a trickle charger. That said you should still see a rise in voltage when reving the bike. More likely the stator is at fault than the regulator IMO. Has your meter got an AC voltage range? If so you can measure the output of the alternator directly but will need some jumpers as ACV must be measured inline. |
Battery was charged properly when new. I pulled it out of the bike and it's currently reading 11.9V, I'm going to charge overnight and try again tomorrow.
Yes, my meter can measure AC voltage. Are there any decent instructions online for measuring the output of the alternator?
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Posted: Tue Jun 10, 2008 1:11 am
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| p51bombay Joined: 23 Jan 2004 Total posts: 9872 |
Just noticed you've an air cooled model and I'm not familiar with those at all. On an LC you just need to disconnect the 3 white wires off the alternator, jumper two of them together and plug your meter into the 3rd one set to ACV, don't know what the output of it will be so start on a high range if it isn't auto ranging. You would be better to ask this on the air cooled forum
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Posted: Tue Jun 10, 2008 1:18 am
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spookyDaily Burner Joined: 23 Jun 2006 Total posts: 108 Location: antwerpen |
i m afraid that s not a good battery .....only 10 volts , mine measures about 13 volt unloaded , maybe 1 cell is broke ?
when your CDI is charged by the altenator ,you can t unplug it .....you ve to test it with the bike running @ idle @ the rectifier connector , multimeter @ AC ....ac voltage .wich goes up when reving ..... could vary a little from bike to bike though!
AC voltage will be about the same between the 3 wires (3 measures )
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Posted: Tue Jun 10, 2008 2:51 pm
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Post subject: Re: RD250 Electrical Problem
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Ardon RD/RZ Jedi Master |
| dufflove wrote: |
Just picked up a '73 RD250 and it has some sort of charging problem. Bike starts and runs OK but dies if you turn on the headlight. Turn signals don't work, but that could be unrelated.
My first thought is to check all connections. Anyone have a better idea or tips? |
These are the guys to ask!!!!!!!!!!
http://www.aircooledrdclub.co.uk/forum/default.asp
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Posted: Tue Jun 10, 2008 6:44 pm
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| p51bombay Joined: 23 Jan 2004 Total posts: 9872 |
| spooky wrote: |
when your CDI is charged by the altenator ,you can t unplug it .....you ve to test it with the bike running @ idle @ the rectifier connector , multimeter @ AC ....ac voltage .wich goes up when reving ..... could vary a little from bike to bike though!
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That is the purpose of the jumper leads, you unplug the connectors, place jumper leads between two of them and your meter inline with the 3rd one, trying to read AC voltage with the plugs connected wont get you a proper reading, it must flow though the meter.
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Posted: Tue Jun 10, 2008 10:31 pm
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spookyDaily Burner Joined: 23 Jun 2006 Total posts: 108 Location: antwerpen |
that serial connection is for the current , not for the voltage
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Posted: Wed Jun 11, 2008 3:14 pm
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