Motorcycle Repair: no compression, piston, falcon

Question
I have a 1986 Yamaha TT225 4-stroke,I was riding it last year and it ran great.I shut it off for a few minutes and went to start it again but it would not start.When I was kicking it over there was a grinding noise coming from the motor.I tried it a few months later and there was no noise but it would'nt start.I checked spark and it was good.I checked comprssion but it barely registered on the tester.Any ideas?    Thanks

Answer
Hi Barry.
 Most likely, if you aren't getting compression it is one or more of the following;

1) Valves are so far off as to be totally unsynchronized, or the valves are not closing properly. Maybe that was your grinding noise?

2) A hole in the valves or piston.

3) The rings are shot and need to be replaced.

Start there and see what you get.
Good luck.
FALCON