ugh chug glug plug

i went to start my 82 kz1000p this morning and the bike just turned until it hit compression then nothing.

lets start at the beginning.

for the last few weeks of riding constant i have noticed after sitting overnight or for several hours while at work the bike turns over very slowly, but still started.
when i was waiting for my new chain(over a week) i let the bike sit and didnt think about starting it.
when i got my chain i tried to start it and i didnt even get a click, but the lights on the gauges came on.
i charged the battery up overnight and in the morning the bike started very smoothly, drove to work and let it sit all day.
after work the bike didnt even crank for a half a second before it started, and the started sounded very smooth and fast.
got home from work and parked it in my shed overnight and here is where i am now.
is there any reason why the bike would crank very easily one time, then not at all the next. i dont want to buy a new battery unless that is what it needs, would this be symptoms of a possibly deeper problem?

Seriously, how old is the battery? If the battery is in good shape time to start looking at your charging system and or harness faults.

If not already done, would assure snug clean connections at battery terminals.

And assure good clean ground connection where negative battery cable attaches to rear of engine.

Good Luck!

the battery was in the bike when i bought it, the PO said it was just one year old.
it takes a charge from my charger and holds it, but it does not seem to recharge properly.
i will cheack the ground on the back of the engine.
also does anyone know of a direct replacement for this size battery which would be low maintenance(sealed or agm for example.
i believe the battery is a ytz20l-bs.

With freshly charged battery installed, has bike's charging system been tested?

Good Luck!

How are the connections? Not only with the battery. But on the rest o the wire loom?

Don't trust the PO. Not their fault in all cases... I'm human and for get things too. Like how long ago the battery was replaced.:blush:

The charging system would be the next thing to be sure of after a good full loom connection check.
Heat, flex and age are a bad combination. Eww sounds wrong.

These older KZ's have the alternator output wiring run under the left engine side cover coming out about where the shift lever is mounted. On the newer bikes, three yellow wires are the output wiring, on the older ones, several color combinations might be used.

I'd look real good at the rubber grommet the wires go through for signs of insulation failure.

For a more through inspection, remove the left foot peg assembly,shift lever, and the sprocket cover.

Inside the cover area you will find three "Bullet" style electrical connectors connecting the alternator output wires to a sub harness that has the neutral switch,oil pressure switch and alternator wiring bundled together.

Vibration and heat may have damaged the insulation or the connections may be corroded/dirty.

check the water level in your battery. How long have you owned the bike.

jswag5, check the clutch lever switch (if you have one).

My 750 twin has one and occasionally acts like this, lights but no starter. Moving the clutch lever slightly changes the contact and allows it to start. I am just living with it rather than replacing or by-passing the switch.

Good Luck.

well, i dropped 90 bucks on a new sealed battery this weekend, it cranks the same way it did a week or 2 ago, slowly but consistent. but the thing is it just cranks once past compression and it fires right up, even dead cold.

im going to pull the starter next weekend to clean it up and see if it cranks any faster.

the engine has like brand new compression, so when the starter hits a compression stroke it slows down, then once the compresion releases it cranks quickly to the next compresion stroke, then slows, but even cold it has not cranked past the second compresion stroke since the battery change.