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Thread: domes

  1. #1

    Join Date
    Dec 2005
    Jax Fl


    My uncle has a 99 gp12 and we got a lowell ported cylinder with pistons for $500. Anyways we put it together. with 41cc riva domes and fresh bore and slugs. It gets 115psi on a MAC gauge. What size domes should he get?

  2. #2
    Flying Scotsman's Avatar
    Join Date
    May 2006
    Have only experienced domes on pro tec and pro design heads have not seen Lowel cylinders.
    My heads were giving 150 psi in the 42cc and 44cc size.
    41 for me would be a little higher.
    Cylinder porting may be why yours is lower im not sure though sounds like something else.
    You should try another gauge to verify readings.
    What did Lowel say compresion should be with those domes.
    you did check piston to Cylinder clearance and ring end gap.
    What squish are you getting.
    When cylinders are bored then honed to specs for your new pistons and rings 120 psi is good for a stock engine.
    You do have new pistons and ring dont you.
    All pistons are not created equal they need the right clearances all 84mm pistons do not mic the same size.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  3. #3
    Pistonwash's Avatar
    Join Date
    Aug 2005
    You need to give Lowell a call and see what he suggests..he's your builder, listen to him.

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