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Hi all,

My girlfriend and I bought a house last year. Lucky for me the previous homeowner left his old mower behind. Unlucky for me... it doesn't work. According to the neighbor it hasn't been run in at least three years. It is a Toro 14-38 XL 14.5 HP rider. Engine is a Briggs and Stratton 28N707 0131-01. One of my (many) summer projects is to get it working again. My first goal is to get the engine to turn over and so far I'm failing. Any help would be much appreciated. Here's what I've done so far:

Replaced battery and tried starting. No luck.
Wired battery directly to starter to rule out bad solenoid/safety switches/etc. Starter would engage but the engine would not turn.
Opened up starter to check for signs of damage. Looked good. Hooked it up to the battery while it was off the engine and it worked.
Removed spark plug and tried starting. Starter is still engaging but engine is not turning.
Removed engine cover and pulled out a MONSTER mouse nest
Removed flywheel and cleaned underneath
Removed belts underneath the engine and greased the shaft
Removed cylinder head, cleaned carbon deposits, cleaned valves
Replaced cylinder head. Checked valve clearances
Removed oil from crank case and flushed with diesel. Refilled with new oil.

After doing all this I was finally able to get the engine to turn over but only if the spark plug is removed. As soon as I replace the spark plug the starter can't make it over the hump on the compression stroke. I bought a new starter just in case that was the problem. Still no luck. Double checked the valve clearances and everything was in spec.

Anyone have any ideas of what I could try next? I would love to get this thing working again. Any help is greatly appreciated. Thanks all

might be the compression release is laying in the bottom of the engine.
the "ACR" or Auto Compression Release is mounted on the camshaft and whenever the engine is spinning at low speeds(when starting) it bumps the exhaust valve letting compression out making it easier to start,
to check on this pull the valve cover off and spin the engine by hand if possible and look for the exhaust rocker arm and push rod to "bump" on the compression stroke. it won't fully depress like when running but move just a little bit.

If you need to order more parts here's all the diagrams, https://www.jackssmallengines.com/j...399999-series/28n700-to-28n799/28n707-0131-01

Further to Scrubbys post.
Remove the rocker cover & spark plug
put your finger on the inlet rocker then rotate the engine with your other hand
You should feel the inlet open then close but about 1/3 of the piston travel before TDC you should feel the inlet just barely open and close.
This is the ACR feature he is talking about.

If you can not feel it ( or see it ) try closing down the inlet valve lash
If you can not notice it at 0.001" then as suggested the ACR is busted
You have to replace the cam shaft to fix it. not a difficult job but requires the engine to be removed & split.
You will need to replace the crankcase gasket & oil seal
The cam comes with followers
We get a kit down here with cam followers gasket & seals which is cheaper than buying parts by themselves.
Avoid the 1/3 price "unbranded" cams you will see all over the web, there is a good reason why they are unbranded and so cheap.

bertsmobile1 said:

Further to Scrubbys post.
Remove the rocker cover & spark plug
put your finger on the inlet rocker then rotate the engine with your other hand
You should feel the inlet open then close but about 1/3 of the piston travel before TDC you should feel the inlet just barely open and close.
This is the ACR feature he is talking about.

If you can not feel it ( or see it ) try closing down the inlet valve lash
If you can not notice it at 0.001" then as suggested the ACR is busted
You have to replace the cam shaft to fix it. not a difficult job but requires the engine to be removed & split.
You will need to replace the crankcase gasket & oil seal
The cam comes with followers
We get a kit down here with cam followers gasket & seals which is cheaper than buying parts by themselves.
Avoid the 1/3 price "unbranded" cams you will see all over the web, there is a good reason why they are unbranded and so cheap.

Click to expand...

does the inlet open for decompression on this motor? I never knew that..
:thumbsup:

Yes I do believe this motor uses the intake valve for decompression.

Yep.
They used to decompress on the exhaust but the EPA nazis made that illegal
All EPA compliant engines decompress on the inlet so it blows unburned fuel out the air filter in place of the exhaust or makes the starting mixture even richer bu passing air which already has fuel in it over the venturi a second time.

Thanks everyone. I have a feeling that is the issue. I heard people talk about the ACR but just assumed this engine didn't have it. Neither of the valves move during the compression stroke. After reading a little more it sounds like this is kind of a common issue. I'll pull the engine apart when I get home tonight and see what I find. Fingers crossed!

Update: Pulled out the cam. ACR is still attached and the spring on it works fine. I'm no expert but what do y'all think?

Look on the other side where the pin goes into the cams lobe. Sometimes they wear flat and don’t contact the follower and provide the lift for decompression.

Agree with MowLife:thumbsup:

I haven't seen one of these before so I'm not sure if it's supposed to stick out more