Engine in John Deere Snow Thrower 522 Cannot Run without Choke

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On Dec 19, 9:57am, snipped-for-privacy@yahoo.com wrote:

Thanks for pointing out that "my simulated load" is just like "no load". As soon as the snow stops, I will try running the machine up the hill (my driveway) while throwing snow at the same time to put it under load to see if the throttle valve will open or not. Seem like I have plenty of opportunity to put the machine (and myself) under load today.
Also thanks for telling me that this is normal for the throttle valve to be closed if the engine is not under load (that is even if we have turned the speed lever to High). I mistakenly assumed that the throttle valve should open up strictly following the speed lever. Thanks for the correction.
Jay Chan
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As mentioned in another of my post, I find that the engine cannot idle slow. According to other web sites, this means there is likely an air leak somewhere in the engine. Seem like you are right.
The hard part is to find out where the air leak is. And I will need to connect an air regulator to my small air compressor and inject 3- lbs-per-sq-in air through the choke air intake and spray soapy water around the engine to see where the bubbles will come out.
Meanwhile, I will have to start using the snow thrower today and tomorrow regardless the fact that the engine cannot idle snow. I think it should not hurt the engine -- just burn more gas.
Jay Chan
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Did it ever idle slow, mine dont.
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I received the snow thrower as a "hand me down" years ago. I was not able to set the speed lever to low. If I tried, the engine would stop. After I cleaned the carburetor a week ago and made adjustment on the high speed mixing needle, I can put the speed lever to low and the engine will continue running. The only remaining problem is that the engine will run in high rpm, not in slow idle speed.
Based on the research on another web site and what have been suggested in this news group, the problem might have to do with air leak. The engine may get air elsewhere from air leak (not just from the air inlet in the carburetor). I don't fully understand this. But I just have to keep this in mind.
Because of the fact that I have been using the snow thrower for years without the use of running it in idle speed, I probably will leave this problem alone.
Jay Chan
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hr(bob) snipped-for-privacy@att.net wrote:

The tension on the governor spring is set by the speed control & the governor maintains it under varying load.
If an engine is off & the control is set to fast, the throttle will be pulled wide open.
MikeB
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It's more expensive to add the required throttle linkage and most people never use that feature anyway. More often than not, it comes down to nothing more than cost of goods to manufacture, though that isn't as exciting as conspiracy theories.
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Slower running engines last longer and run cooler, single speed is cheap to make. 3600 rpm is normal full speed, cut it in half and motor life increases at least 4x. Long life engines run very slow.
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ransley wrote:

And require greater displacement to produce a given horsepower. Like I said, it all comes down to cost. People want cheap, and they want enough power to cut their grass. These motors hardly ever wear out before the equipment they power anyway, change the oil yearly which hardly anyone ever does and a lawnmower engine can last 50 years.
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James Sweet wrote:

My John Deere LA100 manual says idling or operating at less than full throttle can be harmful. Half throttle should be used only for a warm start or a brief warm-up after a cold start. Full throttle should be used for cold starting, running, and shutting off.
I suppose it has a throttle lever for safety, as a quick way to reduce speed.
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An hour rating is better and its from maybe 350-2000 for a cheap Honda, ive worn out a B&S that was well maintained in 350, and I have an 83 Lawnboy thats great. 50 years, with a small lawn.
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ransley wrote:

Yeah that sounds reasonable.
I figure most people mow their lawns about 15 times a year, although obviously that depends on location. If a typical suburban lawn takes roughly a half hour to mow, and 350 hours engine life is good for 46 years. Not saying nobody ever wears them out, but I've scrapped a number of lawnmowers due to rusted out decks but the only motors I've ever junked were ones somebody ran out of oil.
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If by cleaning you mean with spray carb cleaner, that isnt the same as what you soak them in. Are there needle adjustments on the carb, often that is all that is needed. 3600 rpm is a base for most all small power equipment like this, a cheap hour meter usualy has a tach, they have a wire that wraps around the plug wire
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Thanks for telling me that the type of tachometer is called "Hour Meter".
Having said this I decide to get a cheap optical tachometer. The reason is that I have found a way to get access to the spinning part of the engine, and I can use the optical tachometer to measure the rpm of the spinning part of the engine.
Jay Chan
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Jay,
the throttle on these small engines is controlled by a GOVERNOR system, when the engine is under light load, the throttle will be more closed, when the engine is under heavy load the governor senses the engine trying to slow down and will open the throttle to tey to keep it running at a constant speed as the load changes. The governor usually is a mechanical setup with springs and rotating weightsw or fan air pressure usually inside the engine that you cannot see. All you see of the governor is a lever that comes out of the engine and is connected to the springs. This level is suposed to move as a fnuction of the engine spped. You have to understand the concept of the governor to troubleshoot these problems. If you disable the goverenor and operate the engine at wide open throttle and no load, IT WILL over rev and can possible fly apart, that can be dangerous. If you don't nuderstand all this., proceed with caution. When you first start it up after any repair, you have to be ready to SHUT ER DOWN immediatly if it starts to over rev. There are many good websites on small engine repair.
Mark
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On Dec 16, 9:10pm, snipped-for-privacy@yahoo.com wrote:

Thanks for taking the time to warn me about the danger of letting the engine to spin too fast. Yes, I know about this. This is the reason why I want to get a tachometer to make sure I don't let the engine to spin more than what the manufacturer's has recommended (3600 rpm). So far, just by hearing the sound from the engine, the problem with the engine seems to be running too slow and is not running too fast. The tachometer will arrive in this weekend or early next week just in time as a X'mas gift for myself.
Currently I am suspecting that the spring that is supposed to keep the throttle valve open may have become weak; I am waiting for the tachometer before testing this theory in case I manually open the throttle valve too wide and let the engine spins too fast. Or the throttle lever arm is not setup in the correct position; I checked this once by following the manufacturer's recommended setup and I don't think this is the problem.
The hardest part that I can think of is how to simulate the situation when it is running under load while monitoring the rpm using a tachometer. Currently there is no snow on the ground to test the snow thrower. Even if there was snow on the ground, I would have a hard time using the machine to throw snow while holding the handheld tachometer to point at the spinning part of the engine. I may just have to lift the wheels off the ground with wood blocks, and let the wheels and the snow throwing mechanism to free spin. Seem like a "Hour Meter" is a better device for this test instead of the handheld tachometer that I have ordered. Oh well...
Jay Chan
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You have had the engine governor explained to you several times now in this thread. Everything is working properly.
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Jay Chan wrote:

Usually the banjo bolt that holds the float bowl on clogs, it has some tiny holes around it near the head that you can clean out with some piano wire or something similar. As for the tach, the RPM isn't very critical and you can do it by ear usually, otherwise a stroboscope can be used to measure it.
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You are seeing the engine's GOVERNOR in action. The governor senses load on the engine, and opens and closes the throttle to maintain a constant RPM.
When the RPM goes up, the governor closes the throttle. When the RPM goes down, the governor opens the throttle.
It will run at "full speed" with the throttle 80% closed if you are not blowing snow. When you start pushing through a snow bank, the throttle opens up to wide open.

Probably. Some things need to be cleaned again, and it needs to be reassembled correctly. From the sounds of it, the engine is not getting enough fuel. That's why you have to choke it. Choke reduces the amount of air coming in and brings the air/fuel mixture back into balance.
Pay specific attention to the float, needle valve, and seat.
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On Dec 15, 1:24pm, snipped-for-privacy@rochester.rr.com wrote:

Thanks for the suggestion. You are right about the engine is not getting enough fuel and the mixing needle needs to be adjusted. As mentioned in my other post, after I have turned the mixing needle an additional 1/2 turn more open than what the manufacturer suggested, I can keep the choke fully opened and the engine will not stop. Seem like this is the way to send enough fuel to the engine. Still, as mentioned in my other post, the throttle valve is somehow closed even though the engine is under load and the speed lever is set at high speed.
Jay Chan
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