In article ,
Nick Hull wrote:

I feel like a fool for posting this since I should be able to fix it in
my sleep, but I can't. 1983 Kaweasaki Prairie 3-wheel ATV wouldn't
start. After digging into it I found the 3 screws sheared that transmit
starter torque to the flywheel. Fixed that; engine turns, has
compression (50#, admittedly low, likely dirt on valve seats that would
blow out on start since I measures 100# 2 weeks ago). Starter is
turning motor in the correct direction, the intake & exhaust valve
operate in the correct sequence when I turn the crankshaft by hand, The
spark is hot & blue and will jump a .250" gap in air. Timing is not
adjustable but a timing light seems to show a flash at the correct 10
deg BTDC.

I put gas or starting fluid in the spark plug hole and NO firing.

If I try it with the plug just out of the hole I get fire about 3 times
before it runs out of fuel.

If I crank the engine with the hot wire just off the plug I get fire
between the plug & hot wire, so that proves current is flowing thru the
plug gap BUT the engine fires on every stroke so I could just be seeing
the spark at the top of the exhaust cycle.

I have the feeling I am missing something simple & stupid. Tell me what
stupid thing I forgot. Please.

No idea if it'll be any help, but the first thing I would try is replace
the plug. Mine deteriorated to where it would not spark under
compression. It looked fine and sparked nicely in open air, but not in
the cylinder. Cheap fix if your luck's running good lately.

Funniest one was one _cold_ day it wouldn't run more than 3-4 seconds.
After practically disassembling and reassembling the engine, I found
water had frozen in a low part of the exhaust system. First time I had
an engine failure from a frozen up exhaust. Solved the problem with a
hair dryer and thereafter, making sure to rev the engine to expell the
water before shutting down.