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1982 R100/RS Starting problem

phsdommie

New member
Hi,
I have a new-to-me '82 R100/RS that has been sitting for many years and forgive me, but this is the first airhead I have worked on. It was purchased from a guy who never ran it, so we do not have the history. I suspect it was parked for this reason: When I switch the ignition switch on, the headlight and all idiot lights light up appropriately. The starter motor will turn the engine over for a brief period, then suddenly stop. I think I hear a relay click when that happens. All the lights go dead at that time. I can turn the key off and back on again and the lights come on and I'm able to turn the engine over but the same thing occurs. She never has started, yet. If accurate, the odometer claims 54,000 miles and the remainder of the bike is in remarkably good condition.
Any and all thoughts and ideas will be gratefully received and I thank you in advance.
Cheers,
Paul.
 
Paul -

Welcome to the forum! Waking a bike up from a slumber can be frustrating. How confident are you that the battery is OK? Sounds like it needs charging. Do you have a voltmeter, not the one that is in the fairing? Put the voltmeter across the battery terminals and monitor the voltage as you crank the starter. It should not dip below 10v...otherwise, battery is an issue. You can also take it out of the bike and have one of the auto parts places test it.

You could also have corrosion build up on the starter relay. The relay is located under the tank on the left side of the frame backbone. It's a small black cube about an inch square. What happens, when you push the starter button, the contacts inside the relay close. When they close they connect heavy duty wire from the battery to the starter solenoid. If the terminals on the starter relay are corroded, you might not get solid locking of the relay contacts. Typically, one finds the relay and unplugs/replugs it a few times to help clean off the corrosion.

Of course, if the bike has been sitting for a while, you gotta wonder about the carbs and any gas which might have closed some of the small holes in there. You might need to address that down the road.

Check the battery for health and let us know!
 
Thanks so much for the rapid response, 20774. I should have mentioned that the battery is brand new and fully charged. The relay contacts appear clean - yes, I'd already removed it, bench tested it and then removed/replaced it several times. I've also had the float bowls out and removed the main and needle jets and all appear very clean and patent, though I still blasted them with compressed air. I've placed new plugs in case the old ones were fouled (right side had fat spark, left plug fairly weak). The tank was empty and clean (no rust) and the taps flow freely. The engine turns healthily then suddenly all goes dead.
Paul.
 
Well, if the battery is new and the relay has been cleaned up, then you might have to look farther downstream. It still might be instructive to see what the battery voltage is when you push the button. It could be then, that something is wrong with the starter and/or the connections. Could be with the downtime on the bike, the terminals at the starter are corroded. To get to them, you'll need to remove the top cover of the engine. If you're going to do any work on the electrical system, be sure and remove the negative terminal to the battery to avoid any nasty electrical surprises.
 
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