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Hi guys, first time poster here.
I am having trouble starting my mower this season.
It ran a dozen times fine. Now I can’t get her to run.
The engine spins roughly once as the key is turned and stops.
Craftsman 917270850
Briggs and Stratton 461707-0145-E1

There is a new Lawn and Garden battery installed as well as starting solenoid.

could my issue be the actual starter motor? Or by creeping the forum could it be a valve adjustment issue?
Thanks in advance for any advice.

NovaScotia1989 said:

I am having trouble starting my mower this season. It ran a dozen times fine. Now I can’t get her to run. The engine spins roughly once as the key is turned and stops.

Click to expand...

It does sound like the compression release is not working due to valve adjustment.

Born2Mow said:

It does sound like the compression release is not working due to valve adjustment.

Click to expand...

Okay, that will have to be something I check into tomorrow afternoon with the right tools.
Any idea what the feeler gauge should be set to and what the torque spec is buttoning everything back up?

On the opposed twin, (according to the model number provided) the camshaft doesn't appear to have a compression relief mechanism.
To adjust clearance on a flathead you will need to remove the valves and grind the tip of the valve. A LITTLE BIT AT A TIME.
only if the clearance is out of spec.

Born2Mow said:

It does sound like the compression release is not working due to valve adjustment.

Click to expand...

Also how involved is the valve adjustment on this engine? Am I biting off more than I can chew?

Scrubcadet10 said:

View attachment 56742
On the opposed twin, (according to the model number provided) the camshaft doesn't appear to have a compression relief mechanism.
To adjust clearance on a flathead you will need to remove the valves and grind the tip of the valve. A LITTLE BIT AT A TIME.
only if the clearance is out of spec.

Click to expand...

Is there anything else that may be the issue? Sounds extremely involved

NovaScotia1989 said:

Also how involved is the valve adjustment on this engine? Am I biting off more than I can chew?

Click to expand...

Nope, you got to slightly grind down the valve... little at a time, again, that is only IF the clearance is out of the specified range.
you have to remove the valve cover, which is a little plate on the top of the engine, on each side, i would purchase a flat head engine valve spring removal/installer tool, (tons easier), remove the cylinder head(s) which is simple. slowly grind the valve small end, a little, and when i say little, a little at a time. you can take material off, but you can't put it back on. check, clearance, grind some more, check clearance, grind, check, grind check until it's good.
install a new valve cover gasket, as well as head gasket.
If the valve clearance checks out GOOD, i would get a volt meter and start checking voltages. it is possible to get a voltage drop in the Main + wire due to corrosion in the wire or bad ground connections. Or even a bad starter.

Scrubcadet10 said:

View attachment 56742
On the opposed twin, (according to the model number provided) the camshaft doesn't appear to have a compression relief mechanism.
To adjust clearance on a flathead you will need to remove the valves and grind the tip of the valve. A LITTLE BIT AT A TIME.
only if the clearance is out of spec.

Click to expand...

If my engine manual and my riding mower manual have different clearance specs which one do I use?

Engine manual

what level of dicolouration and grim is usually on the valve heads? If any

read it carefully.
The manual usually has clearances WITHOUT SPRINGS installed in the repair section and valve clearances fully assembled in the specifications section.
This is so you can check how you are going when recutting the seats or shortening the valves to reset the lash

NovaScotia1989 said:

Hi guys, first time poster here.
I am having trouble starting my mower this season.
It ran a dozen times fine. Now I can’t get her to run.
The engine spins roughly once as the key is turned and stops.
Craftsman 917270850
Briggs and Stratton 461707-0145-E1

There is a new Lawn and Garden battery installed as well as starting solenoid.

could my issue be the actual starter motor? Or by creeping the forum could it be a valve adjustment issue?
Thanks in advance for any advice.

Click to expand...

That part where you say "it ran a dozen times" was that this season? Knowing that could narrow down your problem. If the engine has sat through a winter and now it won't start, I wouldn't even consider the valves, it's likely bad gas or the result of bad gas.

Joed756 said:

That part where you say "it ran a dozen times" was that this season? Knowing that could narrow down your problem. If the engine has sat through a winter and now it won't start, I wouldn't even consider the valves, it's likely bad gas or the result of bad gas.

Click to expand...

This season

While it could possible be the valve clearance, it is very unlikely on this engine. Much more likely is excessive carbon build up in the cylinder heads as you may have suspected from your question. Next bad cable connections especially where the ground cable attaches to the frame. The starter for these engines is taxed to its' limits when all is right. The starter also has a habit of wearing the top bushing oblong allowing the armature to rub the field magnets. I suggest you check all these possibilities before messing with the valves.

For a Service Manual for your engine, email me at address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

I am thinking either starter problem considering the engine age or carbon (foreign object) on piston or head cylinder head. But here is the valve adjustment info.

Opposed L-head twin cylinder engine

NovaScotia1989 said:

what level of dis-coloration and grime is usually on the valve heads? If any.

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The Intake will be black to neutral. The Exhaust will be the same color as the spark plug.

Well fellas, it was indeed the valve clearance! Or the carbon build up!
thanks very much for your help!