I recently picked up a 1984 Kawasaki KLT200 (non running), and replaced a bunch of stuff on it. I've got it to the point where it idles (albeit low and rough) but stalls and sometimes backfires out the intake when the throttle is pressed. Spark is consistent and strong, timing is good, carb is brand new, and gas is fresh rec90. The exhaust smokes a little, but not enough to tell color. Choking kills it, and the plug gets carboned up after a while. Does anyone have any idea what could be causing this and/or hot to fix it?

 

I think I've found the issue... I took the intake off, sprayed brake cleaner on top of the intake valve, and turned the engine over by hand. Bubbles came up through the brake cleaner on the compression stroke (I don't have a compression tester and couldn't test for leaks earlier). Looks like I'm lapping the valves this weekend.