Yep it happens on the NON turbos....typically caused by too much carbon deposits not allowing the valves to fully close. Won't start because not enough compression...small little bits don't allow valve closure.then yes an overly rich condition in the cc.

Suggestions:

1) A few high speed, high rev runs to blow your engine out. Try to limit the low speed, very short, cold trips, moving the car in the driveway while cold is a killer.

2) Run a good combustion chamber cleaner such as Amsoil PI through.

3) Change your oil to synthetic.

4) Change your fuel brand.

5) Change your spark plug brand.