Honda 1992 XR600 miss firing

sounds like a fuel issue, how long has the bike been sitting? You said it is worse in certain weather conditions, so i don't think electrical would act up in different weather conditions. I am not sure if your bike has carbs or fuel injection. If it has carbs, you most likely have dirty pilot jets.

Your caption says misfires at high, then you say low? You have a 95. Lots of miles I assume. So there are several things that would cause misfires at high and low. First is timing chain/belt, sloppy. Second, would be the valves and rings. Valves worn or bent, not seating right. rings just worn out, not holding compression. Do a compression test and see. Low speed or idle misfires can be from vacuum leaks. check hoses. Low and high rpm misfires can be from ignition problems. Wiring, coil/s, ignition modules.

got a 1996 model xr600 firing alright but not running couple of seconds and then stalls out also blown some smoke on start up for couple of sec once clears it throat seem fine

That sounds like a problem with the pickup coils. they are mounted to your timing plate, Check them for resistance with an ohm meter, they should be around 5k ohms, if one shows infinite you've found the problem.

Looking at this problem laterally rather than logically, what if the pipe leaks when the bike is working and just happens that the air intake ingests the water at high speed. That would make it misfire.
Does it misfire due to revs or speed?

Take your carburetor apart , clean it, and inspect the insides. My similar experience found the slow jet in the bottom of the bowl and a previous cleaner having installed the piston spring in the car top incorrectly. Put everything back to the stock settings (air screw). Double check the intake boot for cracks or separation. The problem is probably very simple , but disassembly will be required.

The Valkyrie is notorious for burning the vacuum lines on the inside of the intake manifolds. They burn, get brittle, and break from back firing up the manifold caused typically by an aftermarket exhaust system. Stock bikes burn the tubes more slowly. Check all six tubes and replace this will probably solve the problem.

If it ain't broke, don't fix it. If the bike has adequate power just go ahead and ride it. Chances are it will get better from use. The rings are probably sticking in the ring grooves creating the low compression. A shot of WD-40 in each spark plug hole, left sitting overnight may help the free up the rings. The brand of oil does not matter much. Just be certain to NOT use synthetics or oils with "Special" additives. They can swell or shrink the cork on the clutch friction plates. Now you need new plates.

DRAIN CARBS FROM PETCOCK AT BOTTOM OF EACH CARB MAKE SURE FUEL DRAINS COMPLETELY THEN TURN FUEL BACK ON, IF THIS IS AN INJECTED MODEL DRAIN TANK AND FLUSH THEN RUN IT HARD FOR 20 MILES OR SO, MAKE SURE YOUR OIL LEVEL IS OK

If you need further help, I’m available over the phone at https://www.6ya.com/expert/michael_00678fd4800d19c5

This is a strange problem. As such, you gotta agree to give me at least a "Helpful" rating even if we don't end up with a fix. After all, I am trying to help.

All that being said, I think the problem is in the carbs. The bike is running lean in the low rev range and now you are putting a load on the engine. I can't identify if your carbs are CV carbs ( Vacuum controlled carb slides), or standard carbs with throttle controlled slides. Assuming standard carbs, For each carb; remove the carb cap and pull out the slide. Now move the clip on the top of the jet needle down one notch. This will richen the low end fuel mix. Now there is more power to handle the load on the engine. Two notches may be needed but start with one.

EXACTLY what bike do you have; i.e. "1996 Honda CBR500 SE" or "1996 Honda CBR500 R6"
Also, is there an electrical switch built into the clutch lever assembly?