R100 GS newbie got trouble !

[gee-yes]

Hi I have just joined the forum as I ve just got myself an R100 GS PD. Unfortunately on my way home from picking it up (1 hour into the journey) it cut out totally, with no battery life at all. The battery was apparently quite new and fully charged. She would only go with a push but then cuts out as soon the revs drop. The battery light doesn't come on with the ignition lights. Anyone out there had a similar experience or any ideas?

 

[Steptoe]

No battery light when the ignition is turned on ( without the engine running) means the battery will be getting no charge with the engine running. So you've been running on the battery power only.

No ignition light on "usually" means the alternator rotor is kaput.

 

[Voyager]

She would only go with a push but then cuts out as soon the revs drop. The battery light doesn't come on with the ignition lights.

As Neil (Steptoe) says, it sounds as though the battery isn't being charged.

But, as the bike appears to run if the revs are kept up it sounds as though the ignition is running straight off the alternator.

That would point to a wiring or battery problem rather than alternator failure - are the battery leads connected properly and is the earth lead earthed ?

(Neil isn't old enough to remember old British bikes . . .My 1959 350 AJS had an emergency run feature - if the ignition key was turned to the left it connected the alternator to the coil and the bike would run without the battery - providing the revs didn't drop).

Sounds familiar

Don't worry; I expect most of us have bought a bike that immediately let us down. My 100GS had a knackered coil and only just got me home from my first run. Fortunately I had a new spare

Welcome to the site and the wonderful world of 'Airheads' .

Bob.

 

[MattW]

For what it's worth, I have experienced this problem but not on a bike (my old camper van) - no ignition light when the key was turned and it ran when the revs were high, but stalled when idling (or if the electrical load was increased - lights switched on etc).

In my case it turned out that the exciter lead had come adrift from the alternator due to crap wiring design (that's Italian auto electrics for you ). I re-routed the exciter cable and re-attached it and all was well. The downside was that I'd killed the battery by repeatedly running it flat.

I'd guess an airhead alternator will be wired in a pretty 'standard' way (although others will no doubt know more), so it might be worth having a thorough check of the wiring before swapping alternators etc - pretty simple to check and a cheap fix if you find a problem.

Hope you get it sorted

M

 

[BillN]

As the others have said............if the generator light is not lit.......the battery will not charge even though everything else is in order because the gen lamp "energises" the rotor, (from the battery), so that the rotor, once spinning fast enough, will charge the battery.

It is very rare that a bulb will fail but this is something that you should also consider

 

[gee-yes]

Thanks Guys helpful stuff - I have checked all the obvious stuff (i think -including the connections to the battery) however I will check a few more things then run a meter over the battery and alternator - I suspect that it is rotor, regulator or alternator related as you say. At least it hasn't put me off a great bike - I still love it.

 

[bowser]

just to stick my two penny worth in, I had a similar problem and everyone said it was the rotor, so go a replacement. #guess what? it was the diode pack !! so it worth checking that as well.