Bike dies after 2 seconds once engine turns over

[ANB123]

I have a 1980 cb750 and I am able to crank it once while really giving it throttle, but once it turns over, it dies within seconds. Then, the engine wont even engage at all (sounds like a dead battery). I can hear a buzzing at this point. I had the battery charged to 100% but it still does the same thing. Is this a simple fix like a choke or has anyone had something similar that could give me some advice on what to do?

Thanks,

ANB

[hocko]

I had a similar problem but the battery was old.I took the starter motor out and replaced the brushes not that worn only 38k But i did it with a new battery once i dont use it during the week.It not a hard job to do.

[Re-run]

Sounds kinda like a solenoid or maybe the starter is not engaging properly.

[CB750Winger]

  I would agree with the others but another possibility is if you recently replaced the spark plugs with something other than NGK. I put new Autolites in my 75 and it would only run a few seconds, load up and die. A friend of mine said they won't run on anything but NGK's, he was right.