Tried to start, but ultimately failed

So I'm working on a kz750N Spectre, and I almost got it running yesterday. Almost. A quick check fo the carbs looked clean, the floats were easy and the fuel pool clear. The battery was dead, so we tried to jump it using a friend's car. It gave a steady, valiant effort in turning over, but never quite made it. It did briefly kick when I added some ether into the air-box, but it wouldn't continue combustion. The spark plugs all gave decent spark, albeit looking a little burnt from previous use.
I'm at a loss for solutions. Any ideas as to what could be the problem?

I know it’s tempting to want to get an old machine running again, and the thought of just a guick jump start on a dead battery might get me quick gratification. Stop. You need a good working battery to have any chance of resurrecting it. Bad things can happen with a jump start. I’ve been there and blew out every bulb when it did start and the charging system went to full charge trying to make up for a bad battery. Not worth the $60 to $80 for a good battery. Start there then try again.

[quote="SpeedBump101" post=822011.... The battery was dead, so we tried to jump it using a friend's car. ....[/quote]

A really BAD idea! Ed

Its ok to jump from a car battery as long as the car is NOT running.
If it fires if you spray carb cleaner into the airbox then dies it means fuel is not getting into the cyinders. If it has not run for a while my initial guess would be blocked pilot jets and possibly blocked choke pick ups. Modern fuel leaves a horrible residue when it evaporates which can block small carb appertures easily.

650ed wrote: [quote="SpeedBump101" post=822011.... The battery was dead, so we tried to jump it using a friend's car. ....

A really BAD idea! Ed[/quote

Only if you don't mind doing A LOT of extra work!
Rick H.

OK guys, thanks for the rebuke . I won't try to jump a bike again. That just goes to show how much I don't know about bikes.
Hey that bit about the carb jets was helpful though, thanks Warren.