AJS & Matchless Owners Club

it would help if you told us what the bike is. Most of us giving advice on this website ride AJS or Matchless machines which are 60 years old or older but from your description I think you have a modern AJS. Having said that I think the the problem you are describing is one I have experienced more than once with a car.
So if you have a fully charged battery and you are using an electric start this will put by far the most call for current (amps) from the battery. If there is a poor connection to earth or to the terminal (usually the negative one if I remember correctly which gets a whiteish corrosion) then instead of spinning the motor properly it just kills the power and the ignition lights go out. stopping trying the starter motor and the power may recover.
So I would try cleaning up the connections to the battery and checking that the earth cable to the frame has not corroded too.

Can you tell us what the bike is and how old it is please.

If it's got an electric starter it ain't any Matchless or AJS that Im aware of. His other post appears to be asking for advice about a Suzuki, so who knows?

Steve

Hope it's not a Lambretta!

As Clive says, and I've had his same experience on cars, almost certainly a bad earth on the battery lead, starter unit or starter solenoid.
On one occasion with a bad battery earth on a Mini the current found its way via the steel choke cable, heating it up and almost setting fire to stuff behind the dashboard.

This is a spam post (note the dodgy links at the bottom). Please ignore this guy.