77 won't start after spark plug change (was running great before)

[r1D30rD13]

My 77 had been running nicely, but it was time to change the plugs, and after I replaced them with new NGK bp7es (same as I was running before) it started backfiring. Eventually, it stopped running entirely. I thought it might have been defective plugs, so I bought more new plugs, and it still won't start. Tried to bump start, it turns over and sounds like its firing but won't start.

What could cause this? It was running fine, but now with new spark plugs it doesn't. Any thoughts?

-More details about the bike - 19k miles, no previous problems starting besides it was pretty cold blooded. I should probably also add that the battery died about the same time. Could the dead battery be causing the problem? Wouldn't it be able to bump start even with a dead battery?

 

[XSLeo]

Probably not. Low battery voltage even bump starting won't get the alternator putting out enough charge to supply the ignition with power. Fully charge your battery.
Leo

 

[r1D30rD13]

Thanks for the advice, I'll get that battery up to a full charge and let you know if I can get it started.

 

[r1D30rD13]

UPDATE:

After getting the battery charged, I was able to get it started (thanks Leo), but it ran like hell for about 5 minutes, struggling to idle at 3k rpms on full choke. I revved it up for a while, thinking after the engine heated up a bit it might run smoother, and all of sudden it was like something popped and it started revving great again. I took the choke off, and took it for a spin to test it out. It ran great for about half a mile, throttle was very responsive through 4 gears, but when I stopped to turn around, it started backfiring and bogging down again, and died.

I got it started a few more times, but it would rev so low and backfire it just kept dying. Any ideas what might be causing this?

 

[wrstar]

UPDATE:

After getting the battery charged, I was able to get it started (thanks Leo), but it ran like hell for about 5 minutes, struggling to idle at 3k rpms on full choke. I revved it up for a while, thinking after the engine heated up a bit it might run smoother, and all of sudden it was like something popped and it started revving great again. I took the choke off, and took it for a spin to test it out. It ran great for about half a mile, throttle was very responsive through 4 gears, but when I stopped to turn around, it started backfiring and bogging down again, and died.

I got it started a few more times, but it would rev so low and backfire it just kept dying. Any ideas what might be causing this?

pull out ur plugs and post pictures of them

 

[Scorpio1963]

Have you tryed putting the old plugs back in to see if it acts the same before the plug change?