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Hot!B&S 190402 engine problems

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tomscub_2018
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2019/12/29 20:05:18 (permalink)
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B&S 190402 engine problems

Hello,
 
I have a 8HP Briggs&Stratton SnowGaurd engine that I cannot get to run correctly. It is on a 1975 Gilson snowblower. I had to put a new carburetor on it because the old one was leaking really bad. The new one will get it to run but not very fast. When I throttle the engine up and turn the mixture screw in, the exhaust gets red hot and shoots flames out of it. I have already done a valve job to it but it did not help very much. Any help with this would be very greatly appreciated.

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    Roy
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    Re: B&S 190402 engine problems 2019/12/29 21:16:50 (permalink)
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    Is the governor spring pulling the throttle wide open?
    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/29 22:24:24 (permalink)
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    At full throttle the throttle plate is wide open and the governor spring is not trying to close it. I don't think I can get the engine to run fast enough to close it. If I try to turn the main jet screw in, the engine dies.
    AVB
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    Re: B&S 190402 engine problems 2019/12/30 06:16:52 (permalink)
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    A couple problems with your understanding of the engine operation.
    1. Turning in the idle or main mixture screws on these updraft carburetors is leaning the fuel mix or not enriching it.
    2. Second the governor are not intended to close the throttle vane, it intended to pull it open to increase to engine's rpm. The governor itself closes the throttle vane against the resistance of the governor spring. It is the balancing act between the spring pulling the throttle vane open and the governor pushing the throttle vane close that sets the governed engine speed.
    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/30 06:33:03 (permalink)
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    AVB
    A couple problems with your understanding of the engine operation.
    1. Turning in the idle or main mixture screws on these updraft carburetors is leaning the fuel mix or not enriching it.
    2. Second the governor are not intended to close the throttle vane, it intended to pull it open to increase to engine's rpm. The governor itself closes the throttle vane against the resistance of the governor spring. It is the balancing act between the spring pulling the throttle vane open and the governor pushing the throttle vane close that sets the governed engine speed.



    Ok, my mistake when I turn the main mixture screw in the mixture leans out and the engine speeds up, it is at this setting that the muffler gets red and starts to shoot fire. However at this setting the engine is still not up to full speed. Second with engine not running and throttle lever pulled all the way up the throttle plate is wide open. That should be correct right?
    AVB
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    Re: B&S 190402 engine problems 2019/12/30 10:29:22 (permalink)
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    The governor spring will be pulling the throttle vane open when not running.
     
    Since this engine is a 1971 model, what the compression numbers looks like? Also double check that the flywheel key isn't partially sheared.
    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/30 12:59:04 (permalink)
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    here is a picture of the key. Can't check compression don't have a tester.

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    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/30 16:27:31 (permalink)
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    This is the picture of the key and keyway
    AVB
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    Re: B&S 190402 engine problems 2019/12/31 07:03:42 (permalink)
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    If I am seeing things right in the image in post #7, the key is fully sheared. But another of the key that not in the shadows might tell us something different. Currently it looks like the crankshaft key-way is at the top and the flywheel key-way is at the 10-11 o'clock position.
     
    If this correct the engine shouldn't even be running as it severly retarded ignition timing wise.
    post edited by AVB - 2019/12/31 07:05:26
    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/31 07:29:21 (permalink)
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    Thank you. I will check and report back to you.
    tomscub_2018
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    Re: B&S 190402 engine problems 2019/12/31 12:50:58 (permalink)
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    Thank you a million AVB, you called it sheared key. Took off the flywheel and the key was split diagonally the long way. Went to hardware store got the closet size key they had, off by a 1/64 of an inch and it worked. Engine runs perfect. This was my dad's snowblower from 1971 or so. He used it up until about 1991 or so. Anyway i found it and bought it back from a guy for $10.00
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