When you line up T1-4, either #1 (on the left as you sit on the bike) or #4 (on the right) will be at Top Dead Centre (TDC). If there is no play on the valves on #1, rotate the engine one whole turn to T1-4 and try again. This is because #1 and #4 go up and down together (as do #2 and #3), so when one of them is at TDC, the other is completing the exhaust stroke.