# Briggs eng. problem



## duggar (Mar 13, 2014)

14 hp. Briggs motor doesn't want to turnover. I have replaced starter and battery and cables. With spark plug out, engines spins just fine, install plug and it will give a spin and then stops, acting like there in not enough voltage. I took the belt off under the motor and it didn't make any difference. Local mechanic thought maybe the head gasket is bad giving equal pressure in the cylinder when cranking. Have good spark and connections. Any ideas? Thanks, Duggar.


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## OptsyEagle (Jul 17, 2007)

Do you have the model number for that B&S motor. 

If it is Overhead Valve (OHV) motor then it is probably the valve lash out of spec. causing the compression release to not kick in. When that happens the little battery will not have enough power to crank it past the compression stroke.

If you give us the model number we can confirm that and get you the specs. and procedure to fix it. Valve adjustment is not very difficult.


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## paulr44 (Oct 14, 2008)

OptsyEagle said:


> Do you have the model number for that B&S motor.
> 
> If it is Overhead Valve (OHV) motor then it is probably the valve lash out of spec. causing the compression release to not kick in. When that happens the little battery will not have enough power to crank it past the compression stroke.
> 
> If you give us the model number we can confirm that and get you the specs. and procedure to fix it. Valve adjustment is not very difficult.


While Optsy is correct, after setting the lash and before reinstalling the rocker cover:

With the spark plug removed, turn the engine over in the normal run direction by hand, while observing the rockers. One (some OEM's use the intake now for emissions reasons) rocker should blip a valve open a tad on the compression stroke. If not, the compression release is broken which requires replacing the camshaft assy. Although RARE, we've seen some B&S home-owner riders have the comp-release fail.


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## duggar (Mar 13, 2014)

This makes more sense, I'll get the motor info tonight and reply. I have one more test todo, which is jumper cable from battery, bypasssing selinoid, straight to starter. thks, d.


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## duggar (Mar 13, 2014)

B & S OHV 14.5 hp, model 287707, type 1224-E1, code 970714ZE. I did my last test with jumper from battery to starter and still did not want to turn over.


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## OptsyEagle (Jul 17, 2007)

OK then, let's take a look at those valves.

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

http://dl.dropboxusercontent.com/u/12502267/B&S Service Manuals/10_276781SingleCylinderOHV.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.

As Paul said, 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.


Lawn Mower Repair Valve Adjustment V-Twin - YouTube


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## duggar (Mar 13, 2014)

Thks, Ill give it a try and let you know the results.


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## duggar (Mar 13, 2014)

I adjusted the valves and didn't seem to help any. I ended up taking it to a local rep. shop and told the guy what I had done. He checked the valves and make a little more tweak of them and still had a problem. Changed starters again and added a new cable from starter to selenoid and started right up. Thanks for your help. D.


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## bonzo (Jun 25, 2005)

*clear up*



paulr44 said:


> While Optsy is correct, after setting the lash and before reinstalling the rocker cover:
> 
> With the spark plug removed, turn the engine over in the normal run direction by hand, while observing the rockers. One (some OEM's use the intake now for emissions reasons) rocker should blip a valve open a tad on the compression stroke. If not, the compression release is broken which requires replacing the camshaft assy. Although RARE, we've seen some B&S home-owner riders have the comp-release fail.


Does this mean that one of the rockers should only move a little while the other one moves a lot more? I have a similar issue and one rocker doesn't move as much as the other and it has me worried. thank s


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