String Trimmer Problem

My daughter's 4 cycle string trimmer seems to be locked up. You can't pull the cord at all. With the spark plug out it pulls okay. My thought is valves stuck closed. Any other ideas for excessive compression? BTW, its a Troy-Bilt.
Mike D.
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Michael Dobony wrote:

Wasp nest in the exhaust?
nate
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One or both valves stuck closed will result in NO compression, not increased compression. The common cause of your symptoms is hydraulic lock, oil and/or liquid gasoline in the cylinder. It can also be caused by an incorrect (too long) spark plug fouling the piston top. An excessive carbon build-up can increase compression but cannot cause lockup which is relieved by removing the spark plug. Try turning the engine over with a finger over the plug hole to generate slight compression and this should give you a pretty good idea what is wrong.
Your engine might be equipped with a starting compression release which is malfunctioning.
Don Young
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On Sat, 25 Apr 2009 20:43:02 -0500, Don Young wrote:

Yup, hydraulic lock. His neighbor told him that yesterday. He told me about it late last night. He took the spark plug out and pulled like crazy, put the spark plug back in and it is running again.
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Michael Dobony wrote:

Hi, 4 cycle on a string trimmer? It must be pretty heavy one!
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On Sat, 25 Apr 2009 21:48:30 -0700, Tony Hwang wrote:

Not much heavier than a similar sized 2 cycle engine.
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On Sat, 25 Apr 2009 21:48:30 -0700, Tony Hwang wrote:

13 lbs. http://www.troybilt.com/webapp/wcs/stores/servlet/product_10001_14102_92359_55009_-1
The 2 cycle equivalent is also 13 lbs. http://www.troybilt.com/webapp/wcs/stores/servlet/product_10001_14102_10149_55008_-1
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Tony Hwang wrote:

the stihl 4-mix units are about 13 ounces heavier than their smoker counter parts in the same size. but well worth it. Either way, you're going to be using a shoulder strap, so it doesn't really matter. You have a unit that will last forever, is quiet, and doesn't smoke like a dodge truck.
s
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Steve Barker wrote:

I got my first string trimmer in 1976. It was great for trimming 300 tombstones. In 1982 I got one to keep clear half a mile of electric fence less than a foot off the grass. It wasn't easy.
So I got a 17-pound Hoffco from Troybuilt. I think Hoffco claimed to have invented the string trimmer, in the 1940s. It had a shoulder strap and handlebars nearly a yard wide. It made trimming almost as quick and easy as walking past.
Nowadays I use it for three yards, which have about half a mile of trimming. It's going strong after 25 years except the plastic spool. If it fails, I'll need one to fit. I wish I knew where to find the dimensions of modern spools.
Over the years I've tried several other trimmers. None has the wide handlebars of the Hoffco. Those handlebars mean precise control against the pull of the line. The Hoffco is also less fatiguing than anything else I've tried.
How come they don't make 'em like that anymore?
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We have roundup now.
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Same reason they don't make much of *anything* like that anymore. Stupid consumers want everything absolutely as cheap as possible, and stupid manufacturers want you to buy a new <whatever> every couple of years.
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SteveBell wrote:

If I had first seen the Hoffco in a store with other brands of similar prices, I would have thought the Hoffco was of lower quality.
The carburetor lacks a squeeze bulb for cold starting.
It's less powerful than is typical of a large trimmer. (The power is adequate, and more power may have meant a shorter motor life.)
Its driveshaft is a flexible cable. (The cable has held up fine and may mean less weight at the head.)
The most important feature is the wide handlebars. I don't know why I don't see it on other trimmers. I wouldn't try to control a motorcycle or a manual scythe with my hands as close as the grips on most trimmers. Wide handlebars allow my to trim along a fence without beating up the line, to trim close to flowers with confidence, and to cut a wide swath across a field without fatigue.
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The wide handlebar type handles have been available as add-on accessories and they work on most trimmers. They can be used with a support strap and if you get everything set up just right it makes trimming a lot easier. I personally have found that a very light weight trimmer used freehand works best for me. I have a heavy duty wheeled trimmer for the tough stuff.
Don Young
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You must have flooded it unless it has some sort of compression release system, but it should still pull, if valve was open it would have no compression.
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