i suspect it will be the ballast resistor that is faulty they break in half usually,its under the front panel its white and about 3 inchs long with a spade terminal on each end (male).some of the early s fights had a small one and a big on look at them and see if they are damaged.a speedfight will not spark properly with a low battery so this could be the problem for the bad running although i have never heard of this senario b4 to b honest.but i do know thet they will not run on a flat or very low battery the cdi/immobiliser needs a good power source.
adam bike doctor
November 2009
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