man, you know how to pick the problem children!
it's really easy to pull the cylinder off and assess the condition, or just pull the pipe off and look through there. normally no compression means a broken piston.
i could probably have it apart in the time it takes to get pizza delivered. i noted your post on kdxrider and looked here for your thread.... cool, easy to find !
anyway, holler and I'll swing by to look at it if you want extra eyes on it.
my quick look:
caliper $20 line $20 pads $9
fender (pricey as hell) $70-90
tires ve33/ve35 $100 and amazing traction
piston (Wisco) and head /basegaskets $120
if you have to split the cases (broken piston or bad bearings) I'll do that for you, it's not hard at all.
the engine looks pretty clean from here. premix will make a bone look terrible if it picks you dirt and gets dry. it's really easy to clean though, just dump some diesel on it and use a2" paint brush.
btw, that's at least a 98 model, because it's a perimeter frame (E model ) with the more desirable larger carb than the kdx220.
if your wheels are tight and the power valve assembly works, you will have a fun bike for less than $600.