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My Craftsman LT1000 with a Briggs and Stratton 180° Opposed Twin Cylinder 19.5HP 42E707 2275 E1 will only crank 1/2 revolution then stop. I can manually turn it past that point then it will crank 1/2 more rev. I thought it was my starter, so I bought a new(used) one. Had the same problem, engine would only turn half way and stop. Even had a local alternator specialist "rebuild" my starter... no difference. It's not my battery, not my cables... as I have jumpered around them.

I did discover something by accident, I tried to start it with only one spark plug installed (left side as viewed from seat), to my surprise, it fired right up! If I replace the right spark plug, it will not start...
Therefore, I have been starting the tractor with only one spark plug installed and reinstalling the second after starting... getting old! But the grass keeps growing.

Where should I begin looking? Is this a valve problem? I have been told it could be an internal compression release on the cam. How do I repair it?

I wish people who know nothing about the engine in question would not try to be important and answer questions. Your engine does not have a mechanical compression release on the camshaft to fail. It utilizes an "Easy Spin" camshaft grind and the camshaft on these engines practically never are a problem. I suggest a couple of things. You may have carbon build up in the head of the cylinder which does not want to turn over causing it to have too high a compression. This is fairly common with this engine. Also, the Intake Valve on that cylinder may have excessive clearance defeating the Easy Spin camshaft. This is not easy to cure. I think I would try something such as SeaFoam per instructions on the container first. IF there is excessive carbon build up, this may remove it. IF no help, the next thing would be to remove the head and see if there is excess carbon and remove it if so. Lastly, remove the valve cover plate for that cylinder, behind the Intake Manifold, and check the valve clearances, especially the Intake which is utilized in compression release. Check with the piston for that cylinder 1/4" down from the top past TDC. That must be fun installing a spark plug in the engine while running, never tried that.

I can send you a Service Manual for your engine if you like, address below, put in proper format and remind me the engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

Tinkerer200 said:

That must be fun installing a spark plug in the engine while running,

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I have got pretty good at it... I use a long extension and a deep socket. The force coming out of the hole centers the spark plug remarkably well, goes in straight and smoothly. Re- attach the wire and away I go. My neighbors don't even ask... they just stare.

Update on my progress...

Walt was kind enough to send me a service manual for my engine. After seeing how east it was to remove the heads I opted for that route instead of the Seafoam. Plus if gave me an excuse to buy a 1/4" torque wrench.... $12 at Harbor Freight... anyone want a coupon? Good for 1/4", 3/8" or 1/2" through the end of May.

Anyways... pulled the heads, did not find as much carbon buildup as I had expected. Gave everything a thorough cleaning, after trying all sorts of brass brushes I found that carb cleaner, steel wool, and lost of elbow grease worked pretty well to remove the carbon. Got them pretty clean. Re-assembled everything... including both spark plugs... and tried jumping with my car. No dice! But a noticeable improvement. Definitely made a difference,. just not enough. Still had to remove one plug to get is started, but it spun over pretty quickly after the cleaning and with one plug removed.

At this point, I don't know if Seafoam will help at all because there is hardly any carbon remaining, but thinking about giving it a try,

Any thoughts?

While the heads were off you should have done the valve lash as you need to pull the heads off to get the valves out.
No one ever checks then ( me included ) unless there are signs of of incorrect clearences because it is a PIA job as you have yo just about dissasemble the engine to do it.

bertsmobile1 said:

While the heads were off you should have done the valve lash

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Yeah I know... hindsight... I guess I need to get a valve spring compressor... if they are out of tolerance, I will want to fix it then.

One thing I don't understand, if they are too long and need to be grinded, how does that happen? Obviously they were the correct length at one point. Forgive me if this is an ignorant question as I am new to small engine repair.

there are two wear mechanism happening.
Rubbing wear on the cam pushrods & rockers.
This makes the gap open further
Errosion of the valve sets by the gasses running across them and physical burning in the case of the exhaust.
This allows the valve to go further into the head and thus closes down the valve gap.

The manual instructs you to do exactly that, gring the valve face & seat to reduce the gap

bertsmobile1 said:

there are two wear mechanism happening.
Rubbing wear on the cam pushrods & rockers.
This makes the gap open further
Errosion of the valve sets by the gasses running across them and physical burning in the case of the exhaust.
This allows the valve to go further into the head and thus closes down the valve gap.

The manual instructs you to do exactly that, gring the valve face & seat to reduce the gap

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Thank you for the clear description. Makes perfect sense.

The manual should give you 2 different dimensions.
One for springs fitted
The other for held in by hand.
I usually go for the smallest by hand and they usually end up just a touch on the tight side and I have never had a problem
Note the inlet & exhaust valve retainers are different types.
Get a pair of bent end tweezers that are sprung closed, make putting the retainers back a lot easier.

Thanks, now I just need a valve lapping tool and a spring compressor...

Another update...

I pulled the heads and removed the valve covers to check the clearances... both intake valves were .002-.003". Both exhaust valves were .005-.006". Bingo, that must be the problem! I haven't yet acquired a valve spring compressor, but after some consideration, I removed the intake valves... carefully ground the stems to achieve .007-.008" without the springs. Re-installed the springs, while saying a few expletives... but got is done. I elected to not remove the exhaust valves as I had so much trouble re-installing the intake valves and they weren't too far out of spec and I understand the intake valves are used for compression release.

Put everything back together.... got my jumper cables... crossed my fingers.... SAME THING. Will not turn over with both plugs installed.

Am I missing something? Or do I simply have two bad starter motors?

I am new to small engines, but I am not new to mechanics... This is getting frustrating! But I am determined to fix this now more than ever.

First thing I would do is use a good set of jumper cables and jump directly from the battery to the starter and see what happens. IF the starter turns over now, you will know the problem is in the wiring between the battery and starter, cables, switches, etc. IF the starter ran OK, use one jumper cable at a time to isolate which side, positive or ground is the problem. You are about out of options. It is not impossible that you do indeed have two bad starters. Have you tried either or both on another engine? Starters for this engine tend to wear the top end/mounting plate bearing oblong letting the armature rub on the fields. Also, holding the starter engaged too long at a time will cause the windings to over heat and loose their effeciency - weak starter.

Walt Conner

Good jumper cables? What are those? I have a decent set, not the best. I have already bypassed all of the wiring, etc... jumping directly from my car battery to the starter.

No I have not checked either starter on another engine, I don't know anyone with a similar engine.

One thing I was just thinking... I am not entirely certain that I checked the clearances nor set them at 1/4" past the compression stroke... I was so focused on measuring the 1/4" that I cannot say for certain that it was the compression stroke.

The top valve is the exhaust and the bottom one is the inlet .
So you poke you pencil down the pug hole and rotate the engine.
You watch the inlet it will open near the top of the stroke and close near the bottom then it will open a gain, just a tiny amount just before tdc .
This is the compression stroke.
The small reopening is the automatic decompression which is why you run just past tdc to make sure you have bypassed the pimple on the cam.
Inlets suck = piston going down
Exhaust blow = piston going up

" jumping directly from my car battery to the starter."

You are missing the point of this test, jumping from car battery doesn't do it.

Walt Conner

bertsmobile1 said:

The top valve is the exhaust and the bottom one is the inlet.

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No, you have it backwards.

Tinkerer200 said:

" jumping directly from my car battery to the starter."

You are missing the point of this test, jumping from car battery doesn't do it.

Walt Conner

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What am I missing? I am eliminating all of the circuitry on the tractor, to simplify the troubleshooting.