You'll probably be replacing the spark plug anyway, so squirt a little mixed fuel in there. I would then move the kicker slowly to let the piston cycle up and down a couple of times without firing the plug. You could even leave the plug out when you're kicking it slowly (make sure there is no dirt).
But draining the tank and carb are a must. I would even rinse the tank out with gas to make sure the sediment's all gone.
I would remove the carb and take the bowl off. Remove the floats, needle, main jet and MOST important remove and clean the pilot jet and passage way. Before you put the bowl back on, make sure the float level is correct. Also, drain the tank, put in fresh gas, plug and kick away!!! Oh, one other thing, make sure the air filter is clean, mice love to build nests in air boxes. :ride:
1st- Pull the carb and spray it clean. Then drain the bowl.
2nd- Pull the reed cage and make sure the reeds haven't gone brittle or made a home for mud-dobbers, etc.
3rd- check the air box for critter furniture, and oil the air filter (or replace it)
4th- Change the tranny oil. If you find water...punt
5th- Pull the plug out. Drop in about a tablesponn of pre-mix, then spin the motor around 5 or 6 times by hand. (This will help to make sure the rings don't get damaged and also sling some fresh oil on the clutch friction plates.
6th- Change the brake fluid and lube the cables.
7th- Check lubrication points. Neck, swing-arm, etc.
8th- Let it sit for a couple of hours. Put a fresh plug in and fire it up.
At this point I would be gentle with it in the beginning just like you would if you were breaking in a fresh rebuild.
Then if everything pans out ok ride the piss out of it. :cool:
Hi, welcome to DRN. I never thought I'd find someone else with an '83 KDX250. I would recommend a manual, but it's been discontinued. I have a manual for a KDX200, but there are still differences. I don't know if it's a common problem, but my motor mounts cracked (which I think caused my pipe to crack as well). You should try to take your swingarm pivot bolt off (I still haven't gotten mine off, but thankfully i just got some pb blaster to help with that) as well as lubricate/replace as many bearings as you can afford. The forks are probably way too soft, so you may want to consider them as well.
As to actually starting the bike, I think everyone above covered all bases.