Won't Spin Past Compression Stroke

[Johner]

Model 33R777
Type 0003 G1
Code 190214ZD
Single cylinder.

Will not spin past compression stroke.
Battery measures 12.8 v. Starter is new (and all this was tried with 2 used starters as well, so 3 different starters).
Battery connections cleaned, starter relay connections cleaned.
Battery voltage measures 12.7 all the way to the starter; battery, starter relay input, starter relay output, starter lug.
Remover spark plug, spins like crazy.
Attached car battery. Will not spin past compression stroke. Remove spark plug. Spins like crazy.
Attach compression gauge, struggles with partial spins, but got 100 psi , so it may register more if the engine could spin enough to give a good test.
So, why, if all parameters measure good, will the starter not get past compression?
Thank you,'
J

If you look at the cylinder you will see ridges in the wall. The piston is cocking and jams. Have experienced this on a 2 cycle.

 

[cope 19]

Hi Andy,

I remember those early "easy spin cams" but I also recall they sacrificed engine torque for easier starting.

From the sound of it, this would make a fixed permanent compression release.

I'm curious to see this design proposal, can you provide a picture example? How does this set screw affect the tappet face?

Next one that I will post a pic
The tappet ic much harder than the screw but the screw only proudest only .012 -.013 and rounded very smooth. It is a finan fix and works great

 

[bitdemon]

Why does a compression release exist? For the weak human pulling the cord. No engine equipped with a starter should ever require a compression release.

And no amount of adjustment of the valves will fix a worn compression release cam lobe. Drain your oil and look for sparklies. May be worse than you think.

Ha! Reminds me of my minibike days from decades ago. Minibike had a 4HP or so B&S engine, and the 'approved' hot-up procedure (I read about it in a magazine) was to tighten up the governor spring a little, drill a smallish hole in the big-end for better splash lubrication, and off-hand grind the compression-relief lump off the heel of the cam. Yep, it was way harder to pull to start with the end result I had to re-rope the pull starter many times - became an expert at that in time!

 

[Bama66]

Model 33R777
Type 0003 G1
Code 190214ZD
Single cylinder.

Will not spin past compression stroke.
Battery measures 12.8 v. Starter is new (and all this was tried with 2 used starters as well, so 3 different starters).
Battery connections cleaned, starter relay connections cleaned.
Battery voltage measures 12.7 all the way to the starter; battery, starter relay input, starter relay output, starter lug.
Remover spark plug, spins like crazy.
Attached car battery. Will not spin past compression stroke. Remove spark plug. Spins like crazy.
Attach compression gauge, struggles with partial spins, but got 100 psi , so it may register more if the engine could spin enough to give a good test.
So, why, if all parameters measure good, will the starter not get past compression?
Thank you,'
J

I

 

[Tommy Copeland]

I don’t see how any of the above suggestions would keep the motor spinning, make sure you or someone else has not installed a spark plug that is too long and the piston is hitting the spark plug.

 

[Auto Doc's]

Hi Tommy,

Without the compression release operating properly the engine compression is too high for the starter to effectively crank the engine consistently.

A larger more powerful starter means increasing the weight of the machine and that is not cost effective.

 

[Espene]

Step 1). Load test battery and clean and tighten all connections.
Step 2). Check valve clearance and adjust as needed.
Step 3). Listen, learn, and don’t overthink things.

Thanks for this tip. I had the same problem and adjusting valves did help

 

[rhkraft]

i have had this happen. A little bump on a fly weight next to the intake cam hits the lifter on the way up and releases the compression just a little so the engine turns over easier when starting. Once it is running, the fly weight rotates the bump out of the way and the lifter tides only on the cam allowing full compression while the engine is running. If the intake valve is adjusted too loose, the bump will still lift the lifter but won't open the valve causing the full compression that won't let the starter pull it through. Properly adjusting the valves solves that. If that doesn't work, the fly weight and bump lifter is broken and the engine has to be torn down to replace it. I have had people bring me rope pulls that pull too hard, and the valve adjustment works if the internals are good. Worth a try.

 

[shootinsteel]

Model 33R777

The compression release is on the intake valve.
It dumps some compression when the piston is just before TDC if the intake valve lash is .003-.005 with the piston 1/4 inch past TDC. .003 slowly turn the engine on the compression stroke and just before TDC you should see the intake valve stem just slightly bump towards open then re-close just before TDC. If you do not see this bump up the compression release on the camshaft might be bad.
Lot of information on-line about compression release on the single cylinder Briggs Intek engines and failure of the compression release and how to adjust the valves to get a compression release.
If the valve lash is at .003 and it still won't crank through insert a .002 feeler gauge under the rocker arm so as to take the lash to .001 and test crank.

Ignore compression readings for now.

Type 0003 G1
Code 190214ZD
Single cylinder.

Will not spin past compression stroke.
Battery measures 12.8 v. Starter is new (and all this was tried with 2 used starters as well, so 3 different starters).
Battery connections cleaned, starter relay connections cleaned.
Battery voltage measures 12.7 all the way to the starter; battery, starter relay input, starter relay output, starter lug.
Remover spark plug, spins like crazy.
Attached car battery. Will not spin past compression stroke. Remove spark plug. Spins like crazy.
Attach compression gauge, struggles with partial spins, but got 100 psi , so it may register more if the engine could spin enough to give a good test.
So, why, if all parameters measure good, will the starter not get past compression?
Thank you,'
J

Model 33R777
Type 0003 G1
Code 190214ZD
Single cylinder.

Will not spin past compression stroke.
Battery measures 12.8 v. Starter is new (and all this was tried with 2 used starters as well, so 3 different starters).
Battery connections cleaned, starter relay connections cleaned.
Battery voltage measures 12.7 all the way to the starter; battery, starter relay input, starter relay output, starter lug.
Remover spark plug, spins like crazy.
Attached car battery. Will not spin past compression stroke. Remove spark plug. Spins like crazy.
Attach compression gauge, struggles with partial spins, but got 100 psi , so it may register more if the engine could spin enough to give a good test.
So, why, if all parameters measure good, will the starter not get past compression?
Thank you,'
J

I had a Briggs and Stratton that did exact same thing, Almost pulled my hair out trying to figure it out! Engine would spin great without spark plug. Turned out it was the manual decompression located on cam. Nearly took to dump before i found problem, Bought an OEM on amazon for about $80. plus crankcase gasket and seals. total cost around $100. Was an easy fix except for old gasket removal. Engine runs wonderful now and has for several years.