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Holes in cylinder wall

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  • Holes in cylinder wall

    A while back I rebuilt a 3 cyl. 60 or 70 hp Rude looper for a friend. It ate a reed and ruined a piston and head. Unfortunately I don't remember the exact year or hp size.
    While I had it apart, I noticed a small drilled hole in each cylinder wall about 1/2 inch above the exhaust ports. These holes entered the exhaust runners. The engine had cast in, equal length exhaust runners surrounded by the water jacket.
    What was the reason for these holes? The factory obviously put them there for a reason.

  • #2
    Re: Holes in cylinder wall

    It's supposed to be an exhaust relief to help the motor idle better. Does it work? Personally, I doubt it does anything, good or bad. Most of the time when the motor gets resleeved those ports are covered. The performance guys plug them. Sometimes the holes are plugged with carbon. Never seen a motor do anything different with them open or closed.


    • #3
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      Re: Holes in cylinder wall

      I wouldn't worry too much about it...Good Luck