82 kz440 wont start

So ive owned the bike for almost a year now and never had a problem oit of it. Then then it started to have issues to where the bike wouldnt start on the bettery. So i changed the battery. While i had the battery oit i decided to chanhe the exhaust gaskets because i had an exhaust leak. Was doingvthat and sheared an exhuast stud. So it set for a few days while i was waiting on the exhaust stud. Got it in and got the bike back together. Put the new battery in. It fired right up. No problem so i let it idle. It ran great no exhuast leaks at all. Then oit of knowwhere it shut off. No idea why. So i went back over and went to hit the starter. It acted sluggish and didnt want to turn over. So i checked my battery. It was holding at 12.9 no issues there. The bike still isnt starting. And all i can hear is the solenoid click over. Can sombody please help me.

Based on what you described (warms up and then stops, now starter won't crank) that can indicate cylinder or bottom end issues. Let's rule those out first. Try pulling/looking at your plugs to read your carb output, you likely had it on choke, so should read a little carbon fouled. If they're clean, you could be running a bit lean, which can cause damage over the long run. While you've got your plugs out, pull your timing cover gasket and rotate the cylinder (using a socket wrench via the valve adjustment process) to confirm that your engine rotates freely. If it doesn't then you very likely have a big project on your hands.

If your engine rotates smoothly via the crank end with the plugs pulled and your starter is still just clicking, check your battery lead to the starter to make sure that it's getting juice. If it is, it could be your starter. I've personally never had starter trouble, so I'm not sure of the typical symptoms, but from what I understand, it can be common for the LTDs. There are starter kits that you can get for them.

If your plugs show that you're getting gas and engine rotates freely with the test above, you could also find a hill and roll-start the bike to confirm it's otherwise running.

At fitst i assumed it was a chargeing issue because thevstarter when it dors turn over is week and sounds like it doesnt have enough juice but there is no voltage drop when i hit the electric start. Well it drops from 12.9 to 12.6 but tgats not a problem. Im wondering if mabey its like an old s10 that a had that had a weak spot in the starter and now its stuck in the weak spot. Im going to try manually bumping the starter over this morning when i roll my ass out of bed and into the garage.

I had starter issues with my bike. You might consider making sure the starter is bolted down correctly and there is no oxidation or crud around the bolts. When mine started giving me trouble it had come lose just enough to cause a bad ground. That's if your engine turns freely.

It could be a bad ground or corroded connector, but it might be the battery. Heavy sulfation on on the plates can kill cells one at a time. The battery can show decent voltage (12.9 seems a bit low), but the battery will not have sufficient amperage. This weakness will be most appear ant when the engine is idling (low output from charging system) and under heavy load like starting. Most major auto parts stores can do a load test to check the true health of the battery. If the sides of the battery are bowed out or look swollen, it is toast and needs to be replaced.

As noted by others, voltage measured across the battery posts is inconclusive, and the battery should be load-tested to determine its true condition. Should service and charge the battery overnight before having it load tested.

If not already done, would also inspect and confirm condition of the ground connection where the negative battery cable attaches to rear of the engine. Especially, check whether the terminal at the end of the cable might be corroded.

Good Fortune!

I was looking through my Clymer manual, it suggests to turn on your headlight and hit the starter, with several options for follow-up based on what the headlight does (in brief: headlight goes completely out, check for a loose connection; headlight dims slightly might be starter problem; headlight dims severely means your battery is spent or the starter or engine may be seized, headlight doesn't dim at all, check your wiring).