1986 Yamaha Moto 4 Timing
First make sure you got spark and compression. Also check to make sure the valves are adjusted right. As for the timing, I have not done it on a moto4 but it has a smaller version of the Warrior motor.. so I'll base everything off that. There should be a little round plastic cap on top of the flywheel cover (left side of the motor when sitting on the quad). Turn that cap off. Also take the large round cover off the same side of the motor and remove the sparkplug. Using a wrench or breaker-bar with a socket to turn the flywheel counter-clockwise until you see a T mark in the little hole on top. It should line up with an arrow or mark inside the hole. You will need to be at T (TDC) on the compression stroke. So open up the valve covers and see if you have some freeplay in the rocker arms. Both valves should be fully closed with some freeplay in the rockers. If the rockers feel tight and/or a value is open you will have to turn the flywheel one more time until T lines up again.. at that point the crank should be at the correct timing for TDC on compression. If the rockers feel tight at both TDC marks you will need to adjust your valves first. If your flywheel doesn't have any lables but just lines like this || then the TDC mark will always be the LAST mark when turning the flywheel counter-clockwise. Your cam sprocket should have a single line on it that will line up with a mark above it in the head when the crank is at TDC.