I have a no start on a briggs and straon 16.5 OHV. It has spark, and fuel. and backfire's through the intake. I took off the top of the motor to check the key way and it was in place. I think its a valve timing issue but what times the valve? I have not removed the flywheel yet because i need a puller. Is there another key way under the flywheel that times the valves
If the intake valve is adjusted top you ought to have .003-0.5 of clearance on the rocker arm. If no longer the valve desires to be adjusted to the most proper clearance. If the clearance is wonderful there is a few incorrect with the valve or push rod. The valve will be held open with carbon. I had a Briggs that the valve seat got here out of the block. it might want to be placed back in in spite of the undeniable fact that it really is a device pastime. i'd pull the pinnacle off and have a glance on the valves.
pull the valve cover , you got a busted intake rocker arm or a bent pushrod. maybe something else but id say 90% chance. edit: omg i said intake rocker lol. i mean't exhaust rocker arm /pushrod. the thing can't get the exhaust out so its popping out the intake likely.
you can,t tell if the key way is sheared by looking at the flywheel it has to be pulled, did you hit something when mowing? good indication that the key is sheared, the valves run off a cam like in a car if not then you have a burnt valve
No, there is not another key. Valve timing is controlled by a gear on the camshaft and a gear on the crankshaft. There are marks stamped on the gears that have to be matched when putting the engine together. Without breaking one of the gears, valve timing will not change. I would guess that you have something wrong with the intake valve or valve seat. Take the valve cover off and see if the valve is moving, and check the clearance. I believe it should be .003-.005. If the valve is moving freely and the clearance is ok the head will have to come off to check the valve head and the seat. Did you hit something with the mower? Are you certain that the key is intact? With the flywheel nut off you should be able to see both keyways and the key. Make sure that you torque the flywheel nut back on to 60 ft lbs or so or you will shear the key when it starts.
