Engine affected by electrics

[Dom]

After many successfull long journeys, my 652 air cooled has developed a rather frustrating problem. The more electrics i have on, the worse and more jittery the acceleration and idling becomes.
Say for example, if I drive at night and am at a junction, with my break lights ,on, the indicator and the windscreen wipers, the car cuts out completely. If the wipers are off, it pulls away very reluctantly and with no power, and so forth.

The battery is only a month old and appears to be giving a good charge. What could this problem be, as i use my car everyday and with the clocks just gone back, frequently in the dark and rain.

Also the HT and LT cables are new, as is the dizzy cap.  
All your help and expertise would be much appreciated.

Kind regards,
Dom

[ChrisRLewis]

Sounds like alternator is not giving enough output/ fanbelt slipping or there is a current drain somewhere?

If the battery is new try giving it a charge overnight it should be ok for around a day and if it does return, chances are it's one of the above.

[Pete126]

Hi Dom, i'm not sure about the air cooled but the bis has a throttle kicker or as they call it a fast idle solenoid, check your manual in electrical, it sounds like this is'nt working, it compensates for the loss of revs when you switch on the lights and other electrics by speeding up the tickover

[banjomandolin]

Pete, The Bis only has a throttle kicker to increase the revs to compensate for the power drain when the electrically driven cooling fan goes on high speed. Air cooled has permanently running fan driven off crankshaft.  No throttle kicker on air cooled.

[banjomandolin]

Hi Dom, I suspect a poor earth connection, either the main earth from battery to body or the flexible strap between engine and body..If there is insufficent metal contact I can visualize all those electrical negative ions from electrical gadgets all queueing up to sqeeze through the poor earth bottleneck, rather like a Tesco checkout on Christmas eve.