Adjusting Valves ??? Piston location??


Old 09-17-08, 05:57 PM
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Join Date: Sep 2008
Posts: 7
Adjusting Valves ??? Piston location??

I have a B & S Vanguard 385777 type 0349 that I need to adjust the valves on. What is the easiest / best way to tell where the piston is? My engine manual says that the piston should be at 1/4" past top dead center.
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Old 09-17-08, 06:29 PM
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Join Date: Oct 2006
Location: Central Texas
Posts: 1,176
Remove the spark plug(s) and valve cover(s).

Identify the intake and exhaust valves.

You need to be approximately 1/4" past TDC on the compression stroke. Slowly rotate the flywheel clockwise until you see the intake valve close. Insert a probe (like a screw driver, pencil or other long straight object) into the spark plug hole, then continue to rotate the flywheel clockwise as the probe is pushed out of the spark plug hole, you will be able to tell when the piston reaches TDC as the probe will stop moving. Apply a little pressure to the probe and rotate the flywheel clockwise, stop when the probe sinks back into the spark plug hole 1/4", if you go a little further that's alright.

This is the position to use to set the valve clearances.
If you have a twin cylinder, repeat this procedure on the other cylinder.
Old 09-17-08, 07:24 PM
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Join Date: Sep 2008
Posts: 7
I have never done this on a mower before so it is all new to me. I have adjusted several motorcycles but they usually have a mark on the flywheel so it is a little easier. Thank you, I will give it a try.

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