My bike wont start again....

Question edited heavily into written English.
Question moved to model category.

First get the battery load tested. Sometimes there isn't enough amps to turn the starter and supply enough power to the ignition as well. Check all 4 spark plugs for condition and gap.

https://www.google.com/search?q=Kawasaki+ZZR250+won%27t+start

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Does it turn over when trying to start? If no then it could be the starter, switch, or battery. Sounds like the starter, especially if you tried another switch.

Sounds like the clutch plates are sticking. Happens over time. what you need to do is disassemble, inspect and clean the plates. If the parts are in good repair, this resolves the sticking issue. I use carb cleaner or brake cleaner.

wd40 all ele parts

Check CDI and battery of your bike. Your ignition switch or starting motor might have problems get it serviced properly.

There are two safety switches that you may need to test. 1) Neutral safety switch- this switch is what tells the bike that it's in neutral and allows the starter to engage. 2) Kickstand safety switch- this switch will not allow the bike to run in gear if the kickstand is down. My initial guess is the neutral safety switch. If the neutral safety switch is bad, then you will not be able to start the bike with the kickstand down because the bike thinks that it's in gear (even if in neutral). This also may explain why the initial intermitent problem of not starting when warm since the metal contacts will expand and possibly not make contact when warmed up. Are you trying to start the bike with the kickstand up or down? If it were the kickstand safety switch, the bike would probably start okay and then die when you put it in gear.

All most every motorcycle has a push down to down shift and pull up to change to the higher gears pattern.The only exception I am aware of is racing conversions on road race bikes which are opposite of what I stated. Your 1981 model has a six speed gear box with the very first gear being the one you will find pushing the shifter down until it stops snicking through the gears and firms up a bit. Then you have neutral the first spot when you pull it up and then 2,3,4,5,6.

Follow the link to available downloads of wiring diagrams and other info. http://www.kz1000r.com/downloads

Hi and welcome to FixYa,

Offhand a couple of possibilities considering it is a 1981 model:

• check the usual, if it is not cranking, either weak battery or starter relay/solenoid. Another to consider is the starter motor or more specifically the carbon brushes;
• ignition switch - check if the coils are getting +12 even when cranking;
• CDI - check if the electronic ignition is getting +12 even when cranking;
• if it is still a point type ignition, check the contact points, gap, dwell and the condenser;
  
• compression test - worn out rings and/or intake valves would cause low compression making the bike hard if not impossible to start.
  

Good luck and Thank you for using FixYa. Happy New Year.