Battery

Hey all,
I recently got a 1981 kz250. It last ran 3 years ago according to the last owner but has been sitting ever since. I will be cleaning her up on monday, changing fluids, cleaning carbs, plugs, etc. and seeing if i can get her to fire up. The battery is dead from sitting for so long and my question is: If I take OUT my car car battery and take out the bike battery put both on a table hook up cables to them for like 20 minutes, you think it would charge the battery enough just to see if she will fire? I searched online and aome people said that its fine as long as they are both same volts, and others said dont do it cuz it will blow the battery. I just want to get enough juice to test because I dont want to buy a new battery and have it sit since I am planning on chopping the bike and hardtailing it. So it wont get used for some time. Anyone ever tried this?

It really depends on the condition of the motorcycle battery. A battery that hasn't been run in 3 years will probably have dead cells, Your best bet is to replace the battery and keep it on a tender until you're ready to install it

Os there a certain type or brand of tender that you would recommend?

www.amazon.com/gp/aw/d/B00068XCQU/ref=mp...sr=8-1&pi=SX200_QL40
A lot of people use this type

I recently got a Ctek US 0.8 smart charger. It seems like a good one to me --- the battery is definitely holding a charge better than when I was using an old Schumacher. Only time will tell if it gets me a better battery life. The unit has a de-sulphation step, so hopefully it will.

Purchase note: see the Ctek site about getting one from an authorized dealer --- I got mine on eebbaayy & made sure they were an auth seller for warranty purposes (one or two weren't).

Using a car battery: I think you can use a 12V car battery (car engine OFF - car keys in pocket). The bike will only pull the current it needs. I removed the old/dead battery from my 81 650 & ran jumper cables from the car --- the bike started & ran fine. Do so at your own risk, though. hee.