What is the easiet way to know that the piston is top center ? When I have my spark plug out and the piston is as close to the plug whole as possible, is that when the piston is at the top center point?

I have the craftsman tractor model no. 917.273380 and the brigss engine is 31c707 and 0230-e1


7 answers

      • San Jose, CA

    Top dead center is at the point where the screwdriver was pushing up and is just... starting to travel downward again.

    It may take more than one try to note exactly at what point your piston has traveled "up" all of the way it can.

  1. Hi Gowin, The easiest way is to have the spark plug removed and place a flat bladed screwdriver into the hole and slowly turn the flywheel, using the screwdriver as gauge to tell when the piston has reached the top most limit. Be careful of the screwdriver and do not allow it to become stuck or do not press it in soo far it will scratch the cylinder wall. Hope this is helpful.

    1. In response to SHC-BillW

      Maybe im doing it wrong...when I stick the screwdriver in I feel the piston pushing the screwdriver back out to me. How do I know when its at the top. Im confused, Sorry. Hope you can explain this to me. Thanks

    2. In response to SHC-BillW

      When the piston is traveling upward the screwdriver will continue to push out at you. Once the piston reaches the top, the screwdriver will stop then begin going back into the cylinder as the piston goes back down. Perform one cycle and mark the screwdriver when you reach the top and just start going back down. You can then complete a second cycle and stop the piston at the exact top point.

    3. In response to SHC-BillW

      Hi Bill,

      Not meaning to hijack Gowin's conversation but thought I'd reach out to you (notice you're in RR - I'm in G'town).

      I've been thru the "sorry can't help you, you're out of warranty" route on the SEAR'S "Help Line" and hoping to get some sound troubleshooting advice online. I have a VT300 that I bought March 2011 and had multiple issues. My current issue involves smoke. After mowing for about 3o minutes, on stopping the mower it coughed out a HUGE cloud of white smoke. I immediately turn it off. Upon restart it ran clean (absolutely no smoke), until about 10 minutes later - again HUGE cloud of white smoke (unprompted).

      I'm hoping (but skeptical) it's water in the tank - it's stored in a shed and has new gas and hasn't shown any history of smoke issues. Worst fear (and gut tells me...) it's something more like oil spilling into the engine or head gasket.

      Any advice on troubleshooting?


    4. In response to SHC-BillW

      The issue could be simple as you are overfull of oil. Check the level and confirm the level. or it could be the gas is settling in the crancase because the carburator is have an issue with the float. There are vidoes on youtube that you can search using lawnmower white smoke when in use.

  2. Hi Gowin! Thanks so much for your question today and including the model number. That will be helpful for the Lawn and Garden experts to answer your question accurately. Check back soon for a reply!