A B&s 18.5 Ohv With Avs. Won't Go Past Com. Stroke When Starting. Checked Batt. Anj. Valves. Same Thing Wrong. Can Turn Back By Hand And Start. Don't Know Where To Look Now. Maybe Something In The Avs?

Adjusted valves... I'm sure to the correct specs in the owners manual (they can be found in the engines owners manual, on the briggs site by entering the model number on the ohv cover) ? http://faqs.custhelp.com/cgi-bin/faqs.cfg/php/enduser/std_adp.php?p_faqid=3441&p_created=1101860144

Because this sounds exactly like out of adjustment valves.
The avs has the same principle as the synchro balanced engines... its just a counter wieght (improved design) that helps with vibrations... (anti vibration system)