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As the title says, I've and John Deere La110 with a v twin Briggs & stratton engine. I think its running on one cylinder. I should mention I'm not that experienced with engines.

Symptoms:

• Low on power - bogs down when you engage the manual blade lever. After it warms up its less likely to bog down.
• Thirsty on fuel - a lot more so than it was last season.
• Noisy - although there's a crack in the exhaust so this could account for the noise.
• If I disconnect the spark plug on the right hand cylinder, she wont start and flames/pops from the connected side. With left disconnected and right connected she fires up fine.
• Valve cover on right hand side is hot to touch if you run from cold for a few mins. Left hand side is only barely warm.

What I've tried so far:

• Replaced both spark plugs.
• Replaced both ignition coils (I wasn't getting any reading off ohm meter from old ones)
• Removed the valve cover on the right hand cylinder. Push rods are straight and rockers look to have correct amount of travel.

Someone suggested that it might be blockage in the fuel jets in the carburetor but I'm slow to go at that myself as it looks like a bit of a handful taking it apart. Just wondering if anyone out there has any other ideas what it could be before I give up?

Any help is much appreciated.

Thanks
David

Pull your plugs and run a compression test , hot valve cover on one side might indicate a burnt exhaust valve
How was it running before this issue ? A little history on the machine will go a long way in trouble shooting what's goin on now. If you don't have a compression tester stick your finger into the spark plug hole and get an idea of one cylinder compared to the other.

Look at the valves on the other side.

So I looked at the valves on the other side and they look ok too (to the best of my knowledge).

I don't have a compression tester but I tried as you suggested Bertrrr and I don't feel any push or pull when I turn the fly wheel. On either spark plug hole. I'm assuming this should be noticeable enough? I'll try to pick up a tester during the week to be sure. There's a squeak out of the carburetor when I do turn the fly wheel - almost like air coming out of a balloon. Not sure if this is normal or an indication that a gasket is gone somewhere?

As for as history goes, I don't have much. I got it cheap two years ago and have just used it to maintain a half acre lawn area at home. It ran fine last season, but noticeably down on power and thirsty this season. I've a 6.5hp Toro push mower and it tackles cutting better than it. Also I'm thinking it was an engine swap, as from what I've read I think the John Deere LA110 came with a 19.5hp single cylinder engine.

Thanks for the replies - much appreciated.

You should notice some sort of compression coming from the spark plug hole but might have to almost close off the whole opening only letting a tiny bit of blow by. Were the plugs clean when you removed them ? Burnt looking or dry and gray ? Black looking plugs indicate no fire, gray and clean show there was good spark, Did you by chance run it low on oil? Rings may be stuck , compression tester will tell the tell.

Timing might be off due to the flywheel key shearing. $2.13 key solved my problem. But it further cost over $250 more because previous owner drove it overheating the cylinder head which pushed out the valve guides bending the pushrods. New cylinder head, new pushrods, new gaskets needed because $2.13 key sheared.

Yep, John Deere LA110 series usually comes with single cylinder around 19 horsepower.

Check valve cover for: Model, Type, and Code.
First two digits on code are year of manufacture.

TiIngot said:

Timing might be off due to the flywheel key shearing. $2.13 key solved my problem. But it further cost over $250 more because previous owner drove it overheating the cylinder head which pushed out the valve guides bending the pushrods. New cylinder head, new pushrods, new gaskets needed because $2.13 key sheared.

Click to expand...

Sorry about the delay in getting back on this - work has been taking up any free time to look at it further.

Bertrrr: Plugs do look black/carbonised - and as I mentioned I've only replaced them recently. I haven't run her low on oil myself but I can't say the same about past history.

I got a compression tester and ran a test twice on both (this is from cold). 105psi on the good side and only 25psi on the suspect side. I've read compression tests aren't that accurate on a vtwin due to some auto pressure release aid - but I'm guessing that the difference is still fairly indicative of the issue.

Tilngot : I took a video of the valve action on suspect side. I'll try attaching a link. Seems to me like there is movement/wobble in the cylinder valve rod/rocker after the exhaust cycle (but again my untrained eye). At around 10 and 13 seconds in. Maybe this is normal though?

Thanks again

Link to video

The one on the bottom looks a little tight. What are the valve clearances?

Hi Fish,

Unfortunately the feeler gauge I have only goes down to .008 (I think I read somewhere its supposed to be .004 clearance) so was a bit reluctant to go adjusting until I picked up a new one. .008 was very tight on the intake but wouldn't fit in the gap for the exhaust valve - so maybe it is too tight (and intakes too loose).

I guess that's my next step - get a new gauge and make sure they are correctly adjusted?

I did the "screw driver in the spark plug" test too on both sides and the pistons are moving as expected.

davidsh said:

Hi Fish,

Unfortunately the feeler gauge I have only goes down to .008 (I think I read somewhere its supposed to be .004 clearance) so was a bit reluctant to go adjusting until I picked up a new one. .008 was very tight on the intake but wouldn't fit in the gap for the exhaust valve - so maybe it is too tight (and intakes too loose).

I guess that's my next step - get a new gauge and make sure they are correctly adjusted?

I did the "screw driver in the spark plug" test too on both sides and the pistons are moving as expected.

Click to expand...

Your compression readings on cylinders are varying widely. Don’t think adjusting valves will be the fix for that large a difference, however, it is a good first step.

The one valve/rocker looks tight {as in not letting the valve fully close}. But unless the jamb nut/adjuster is loose, it would mean that something else is up, like maybe a loose valve seat.
But I may be wrong, as I am not there to really see things.

Fish said:

The one valve/rocker looks tight {as in not letting the valve fully close}. But unless the jamb nut/adjuster is loose, it would mean that something else is up, like maybe a loose valve seat.
But I may be wrong, as I am not there to really see things.

Click to expand...

I finally got my hands on a feeler gauge (ordered it and got lost in the post so had to wait for another). Valve clearances on the intakes were very big and the exhaust ones were very tight. Adjusted on both sides and am getting compression readings of 125 on the good side and 75 on the bad side (the cylinder that wasn't firing). That's up from 105 on the good side and 25 on the bad side pre-adjustment. I also replaced and resealed the valve gaskets - (not sure if this makes a difference but the gaskets were in poor condition)

I think that both cylinders are firing now because she's not bogging down when I engage the blade. So thanks very much for all the suggestions and help!

Fish - I guess there's something else at play here as you suggest with the lower reading on the the cylinder that wasn't firing previously. Am I ok to motor on, or should I investigate further for fear of causing damage?

Thanks again
David

It is hard to say, it is likely a valve leaking or head gasket. If it were mine, I would run it a bit and see what it does. If it is a bad head gasket, you will likely start burning oil, if the bad spot is at the pushrod chamber.
I never mess with compression gauges with these engines, as the compression release mechanisms mess with the readings normally.

Fish said:

It is hard to say, it is likely a valve leaking or head gasket. If it were mine, I would run it a bit and see what it does. If it is a bad head gasket, you will likely start burning oil, if the bad spot is at the pushrod chamber.
I never mess with compression gauges with these engines, as the compression release mechanisms mess with the readings normally.

Click to expand...

Thanks Fish - I'll think I'll go with that and see how I get on. Thanks again everyone for the help

This sounds like a blown head gasket on the low compression side to me. Pull the head off.