Runs like new TB220 self prop. 21”mower

ICMadness

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I have a 3-4 year old Troy bilt TB220. Walk behind mower 21” self propelled and I’ve replaced the whole carburetor assembly and spark plug this year because it wouldn’t start but every 10-20th pull and only run a few minutes just enough to encourage 10-20 more pulls. After replacing older pieces it started on the first pull and will run like new indefinitely even if I push it up a hill down sideways it still runs but as soon as it touches grass it dies and it doesn’t bog down and die it dies as if I pulled the spark plug wire. I’ve seen so much help given on this site I’m surprised I couldn’t match my symptoms for a fix but I haven’t been able to. Thanks for any advice
 

bertsmobile1

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That is the sort of problem you get with a cracked timing key in the flywheel or a carb with no main jet.
But a full service would not hurt
So start with the mechanical things like valve lash .
Then check the key
The check the carb by doing the following.
Sitting outside your shed, manually open the throttle fully by moving the governor rod with our fingers.
Watch where you put your other hand .
Let us know what happens .
 

ICMadness

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That is the sort of problem you get with a cracked timing key in the flywheel or a carb with no main jet.
But a full service would not hurt
So start with the mechanical things like valve lash .
Then check the key
The check the carb by doing the following.
Sitting outside your shed, manually open the throttle fully by moving the governor rod with our fingers.
Watch where you put your other hand .
Let us know what happens .
I don’t know what a valve lash or a key is but when I do as u said it doesn’t idle up it acts like it’s got full throttle even though it’s idling when I Don’t have my finger on the throttle. Now it takes starting fluid to start it but when it starts it runs like new. The carburetor Was all intact and brand new when I put it on and I didn’t have to prime it or anything it started on the first pull.now I know what u mean by the key under the flywheel. If it’s as hard as on my old mustang I might need to just get a new mower. I will listen to any suggestions and try them. Tks for ur thot on this already.
 

bertsmobile1

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I am having trouble following what you said
So you started the engine and it idled as normal .
Then when you moved the governor shaft to open up the carburettor did
1) nothing happen stayed at the same speed
2) increased speed and sounded like it would take off of I pushed it right to the end
3) stop
 

bertsmobile1

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I don’t know what a valve lash or a key is but when I do as u said it doesn’t idle up it acts like it’s got full throttle even though it’s idling when I Don’t have my finger on the throttle. Now it takes starting fluid to start it but when it starts it runs like new. The carburetor Was all intact and brand new when I put it on and I didn’t have to prime it or anything it started on the first pull.now I know what u mean by the key under the flywheel. If it’s as hard as on my old mustang I might need to just get a new mower. I will listen to any suggestions and try them. Tks for ur thot on this already.
I kept these two replies separate to keep things clear
Valve lash is the amount of space between the rocker & the valve to allow for thermal expansion.
It has to be between an upper & lower limit for the engine to run properly .
The timing key is under the flywheel to check it properly you need to remove the blower housing and the flywheel
To do a rough check you remover the blower housing and the flywheel retainers ( nut or bolt ) and with a strong magnifier check the 2 slots make a perfect square .
After reading your last response I would suggest you check the throttle cable has not slipped from under the retainer clamp so is not allowing the choke to close fully and restricting the maximum amount the throttle can open .
 
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