These are custom made Darton MID Sleeves for the Seadoo Rotax motor.  They come ready for a 102mm bore and can be bored to 104mm.  The MID design allows you to replace the sleeve if it is damaged.  CNC machining is required for installat

More boost means you need more clamping force on the head gasket.  This upgrades the current 11mm studs to 1/2" (12.7mm).  Allows more torque on the stud without excessive stretching.  Requires machining to block and head (see machi

Installation of Darton MID sleeves in the Rotax block.  This is done professionally on our CNC equipment.  Send us your core to have this service done.  We are the exclusive dealer for the Darton Rotax MID Sleeve Kit.  Cost of sleev