1979 gs850 problem starting

[Guest]

i have a 1979 gs850 i think its a us import (headlight always on)the problem is that it will start sometimes but only when i let go of the starter button, i have checked voltage at cdi (aftermarket elec ign fitted) and its just above 9v with ign on when the start button is pressed it drops to 6v + could it be the starter or just bad wireing also plugs are sooted up the bike was stood around for over a year before i bought it ,and it has been parked up all winter,i had it running last year but it ran bad then, urgent help needed cheers can i just say that the battery is new and even using jumpack makes no difference even though it does turn over quicker

[hannibal]

You have a pretty big voltage drop at the igniter. Check your wiring.

[roeme]

Yup, what hannibal said. Check wiring for corroded connectors. You can find the wiring schematic on BikeCliffs' Page, link in my signature.

[Redman]

...................... it will start sometimes but only when i let go of the starter button...................

That is a symptom of marginal battery, or maybe just a not well charged battery.
While runnig the starter motor, the battery is not strong enogh to keep up the voltage, and at that low of voltage the ignition doesnt work. When let off the starter button the voltage recovers quickly, the engine is still turning over, the ignition recovers, and it starts.

You did say was new battery.... new last year? and bike has sat unused for some time?
Maybe find a good small battery charger (1 amp), see if things different after a good charge.

...................... .................. .................... .............. i have checked voltage at cdi (aftermarket elec ign fitted) and its just above 9v with ign on when the start button is pressed it drops to 6v +...................

You didnt say what the battery voltage was.
You measure that 9 (and then 6) from the coil(s) org/wht wire to the ground...? or across the two wires on the coil....?

[Steve]

Just for fun and games, connect another battery to your bike. Yes, it can still be installed in another vehicle, but that other vehicle must NOT be running. I'll bet your bike works much better. Sounds like it's time for a(nother) new battery.

If it still does not start, there is probably a BUNCH of maintenance that needs to be caught up.

.

[johngee]

right update, the battery is brand new and has 12.5v i have removed the wireing loom ,clocks and all the other bits and stripped it ,cutting out all bad joints /contacts etc and soldered all joints ,i have also removed all the crap i dont need ie auto indicators and control unit ,i have now a pile of old wireing on the floor which is not needed and the loom is much thinner ,so now all i have to do is re-fit it all and try again ,will let you now how it all works out cheers for info

[johngee]

so finaly got round to putting the bike back together and whoopee it started first time so getting rid of all that crap and soldering all the connections paid off well worth doing if you are having the same problems happy days