Bike won't start out of ideas of what to check

I've got a 1982 KZ440 D4(belt) I can't get the bike to start after winter storage. The carbs were rebuilt over the winter. I've adjusted the mixture screws correctly. Checked the volts in the battery, 12.45. Tested the starter, it tested positive. Put on a new starter relay, the old one went bad. Bike still won't start and when trying to start it after a few seconds of it cranking with no start it sounds like its dying down. To be more clear, the cranking is slowing down. Is this normal? I'm running out of ideas of what to check. I'm going to check compression and the spark plugs tomorrow. Any other ideas? Would the carbs being out of sync effect this? The float seat got screwed up because the seat wouldn't come out I guess so the guy pried so hard on the seat that he had to reopen it and adjusted the float of that side to match the float on the other side. Any suggestions are greatly appreciated!

i would check for spark clearly. my ignition system went out over night. after i finally figured that out months later it was hard to get it started but i used some starting fluid in the back of the carbs and it would run for a second then die. after using the whole can just using tiny sprays i covered the air side of one of the carbs with my hand and it started right up. but 12.4v is a little low ive noticed with mine. i would use the battery from my truck (unhooked from the truck) as a jumper battery and it helps cranking for sure!

I tested the compression and the spark plugs. It looks like the compression is low. Cylinder 1 is at 70 and cylinder 2 is at 65. The spark plugs could be replaced, but they were testing positive. I'm guessing low compression would be a very difficult fix?

Depends whats causing it. Either head gasket, rings/bores or valves. When you checked the compression did you have all the plugs out and the throttle WIDE open as you should? If yes then whatever the cause will mean head off at least.

70psi with a dead cold, dry engine will still fire off and maybe even start if everything else is right.
Let’s hear how you checked your compression.
A dry engine isn’t going to have stellar compression and we don’t even know if you know how to check for spark...
More info of what you’ve done and how you’ve done it.

Duplicate. Issues with my connection today

Warren3200gt wrote: Depends whats causing it. Either head gasket, rings/bores or valves. When you checked the compression did you have all the plugs out and the throttle WIDE open as you should? If yes then whatever the cause will mean head off at least.

I'm with Warren and Mission on this one. Throttle blades wide open? Keep in mind we don't know how much experience you have so the details count here. With that in mind, ZERO disrespect when I ask questions and likely true for the others.

• We don't know who rebuilt the carbs and if they truly know what they are doing. Admittedly I'm a fussy guy but I shuddered when I heard about messing up the float seat and prying. Floats and the seat set the fuel level in the bowl which is critical to proper operation.
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    12.4V on the battery is good but that doesn't mean it isn't dying because it cannot source enough current. It depends on how quickly it is running down. A proper battery check like the ones done at auto parts stores/ shops check the battery's ability to deliver current. I'd advise against jump starting the bike from a car or truck, you may roast something.
    
    I'd check valve clearances before pulling the head.