# Briggs I/C 13.5 HP Cranks slowly



## Florida

Hi , 
I have a Briggs and Stratton engine on a murray riding lawn mower that cranks over but gets to a certain point then either stops cranking or barely moves.

I have new battery , and have tried jumping it directly to the starter using a battery charger and my truck battery .

It seems to crank better with the spark plug out , when I do this no liquid comes out of the hole . Any suggestions or help would be appreciated as I am at a loss as to why it will not fire up .
I have attached 2 pictures showing model number and the engine plate itself 
Thanks Again


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## OptsyEagle

The symptoms you have indicate a possible malfunctioning compression release, most likely caused by valves out of specification.

This is an easy check and fix if I am right.

Here is the manual for your motor. I do believe it is an overhead valve engine.

http://dl.dropboxusercontent.com/u/1...ylinderOHV.pdf

The valve clearance specs. for yours is on page 170. Your intake valve lash should be 0.003" to 0.005" and your exhaust valve should be 0.005" to 0.007".

The procedure to adjust them is on page 21 but in a nutshell here is how it is done.

First you remove the valve cover. Then remove the spark plug. Now turn the flywheel clockwise, by hand, and observe the movement of the valves to determine which one is intake and which is exhaust. (usually the bottom is the intake but make sure). When the piston is moving on the compression stroke, place the rubber end of a pencil in the cylinder hole, onto the piston, and observe when the piston is at top dead center. Now make a mark on the pencil and another mark 1/4" above it. This is just to measure the movement of the piston inside. Now turn the flywheel so that the piston is 1/4inch past top dead center (roughly. You are just ensuring that both valves are fully closed).

Now I like to measure the valve lash before and after adjustment, so do that now. If either needs adjustment, take a torx screw driver and loosen the lock on the hex nut. I think a 10mm wrench turns the hex nut. Once the lock is off, place a 0.004" feeler guage into the intake's valve lash and turn the 10mm wrench until the valve is very snug against the 0.004" feeler guage. Jiggle the rocker arm if you have to. Once set, tighten the torx screw to about 4 ft/lbs. Do this for both valves (although the intake is where the compression release will be and remember the exhaust spec. is 0.006") and then replace the valve cover.

Once the valve lashes are set, rotate the flywheel again and keep a very close eye on the intake valve. What you should see is that as the motor moves onto the compression stroke, the intake valve will close fully. As you keep rotating the flywheel you should see a very small bump in that valve. If you do, then you know your compression release is working and with the valve lash set, she should start up just fine. If you don't see it, give starting it a try anyways, but you may have a camshaft failure and unfortunately that is more difficult to fix. I bet you don't. Valve lash adjustment is basically regular maintenance and if it has never been done for a long time, it is probably due and will probably fix your problem.


Put the spark plug back in and try it again.

Here is a video to help if you have never done this before. Different motor but everything is pretty much the same, except perhaps the specs.

https://www.youtube.com/watch?v=hGkn0jR9RJM


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