1978 kz400 wont start! HELP PLEASE!!!!!!

Your kz400 may need a healthy battery to run -- I found this in another (older) post here on the board for another kz400 owner whose kz400 wouldn't start:

"Sucess! I don't know what I did different today than the last several attempts, but I kicked it over today and she fired right up! My new battery ran dead, so I hooked it up to my car battery and that seemed to make the difference. I don't understand why battery charge would make a difference when kick starting it. Either way, it's running and that's a good thing. Now on to getting the electric start to work."


I was about to jump on your 'no neutral light, no low beam' comments and say "charge your battery then try it" but since I've never owned a kz400 I wasn't sure if it was set up to require a healthy battery to run. Some bikes will start right up with a dead battery -- they (I believe) have a magnetized rotor in the alternator (a magneto).

But some bikes *will not start* without a healthy battery because they do not have a magnetized rotor in the alternator.

Funny story, I bought a low-mileage (4900 miles) perfect-condition '79 Honda 750f Supersport, easily worth $2k for pennies because the bike wouldn't start and the owner showed me 'look, the rotor degmagnetized (holds an iron rod up to rotor) and I don't want to spend $300 on a new rotor for this old bike' that is when I learned about the "needs battery to run/doesn't need battery to run" deal. I put in a new battery, ran like new, I have that bike right now, beautiful machine.


Charge your battery or buy a new one if yours is bad. Your kz400 sounds like it needs a healthy battery to run based on this kz400 post:

kzrider.com/forum/2-engine/376723-at-a-l...etting-kz400-running


Read the 9th message down the page where the owner gets the bike running by connecting the bike up to a good 12volt energy source.

2wheeldeal wrote: Hello everyone! My name is Dylan i am 21 years old and live in Denver Colorado. I am new to this forum and also new to the mechanic aspect of motorcycles. this is my first bike and not sure on how to fix it but would like to do it myself. Ok here is my problem, once again my bike is a kz4oo 1978 and i have cleaned the carbs spotless, motor cranks and sparks but for some reason wont start up. we have had it running for a solid 45seconds and it died.

make sure the vent in the gas cap is clear so it's not vapor locking the fuel tank.

Also: check the fuel levels in the bowls using a clear tube.

Check timing advancer assembly to make sure it's not stuck. If the timing is too far advanced it will be impossible to start.

I agree it's almost certainly lack of air filters/air box. Put it back to stock and it will be very easy to get running.

Thanks guys i will be sure to give that a try and give a update