Ducati Outboard

Discussion in 'Outboards' started by deka, Dec 21, 2015.

  1. deka
    Joined: Dec 2015
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    deka Junior Member

    Hi, have just got a 6hp? ducati outboard, it didnt seem to be pumping water, so I removed the leg to check the impeller. Problem is that there is no impeller there, thou there is a pipe that runs from the engine down to the bottom of the leg.There seems to have been some sort of brass fitting at the end of the pipe at the leg end (filter?) which looked to be damaged,which could impair the flow of water, if this is what this pipe does? I have searched the internet for info on these engines but there seems to be very little out there, so any info that anyone can give me would be appreciated. thanks.
     
  2. SukiSolo
    Joined: Dec 2012
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    SukiSolo Senior Member

    Never even knew thay made outboards! Had a 250 single m/cycle way back in the mid 70s though, not too bad.

    This link does list Impellors, trouble is it does not list the model No's of the motors. TBH if it was really old impellor it would have turned to dust and disintegrated. Make sure you have the keyway to fix it from rotating when you get a new one or maybe the shaft and impellor already have sufficient profile to stop spinning on the shaft. A flat on the shaft should indicate something, or a Woodruff key slot.

    http://roadandrace.com.au/ducati_outboard.htm

    Try e-mailing these guys, maybe they can help.
     
  3. deka
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    deka Junior Member

    there is no sign of any impeller ever been fitted, the only shaft that turns is the one that drives the prop.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Maybe an air-cooled engine ?
     
  5. deka
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    deka Junior Member

    ducati

    was starting to think along those lines, maybe it is air cooled as there are fins around the engine, but I would still like to know what the metal tube from the engine to the bottom of the leg is for?
     
  6. Mr Efficiency
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    Mr Efficiency Senior Member

    Some Japanese brands had air-cooled engines, maybe around 5 hp. Noisy, like most air-cooled engines. Not sure what the tube would be though.
     
  7. CDK
    Joined: Aug 2007
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    CDK retired engineer

    Probably hybrid cooling like on an old Tomos. Exhaust gas enters the leg, causes the pressure to rise. The water level in the tube goes up and provides cooling to lower side of the engine. No pump, no impeller, utter simplicity!
     
  8. deka
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    deka Junior Member

    ducati

    Thanks all.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    I'm puzzled about how that actually works.
     
  10. philSweet
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    philSweet Senior Member

    Some motors, particularly very light ones, used water cooling just for the head. The block was air cooled. This worked because the max temp was at the top during tdc. Burt Rutan modified the Voyager's motors to run this way. As the piston expanded, temps dropped quickly. So a simple water gallery kept it from cooking. I haven't seen an OB like this, but it makes sense that a one or two cylinder motor could just use exhaust pulses to force water through. The bulge in the lift tube would house a check valve, I presume.
     
  11. Barry
    Joined: Mar 2002
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    Barry Senior Member

    Turn the engine so the fitting is at the highest point and poor water into it. See where it goes or comes out. As the fitting is under water when operating, there should not be any chance of water damage
     
  12. Barry
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    Barry Senior Member

  13. deka
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    deka Junior Member

    ducati

    Hi,thanks Barry for the you tube link, that is exactly the same engine as mine,so it is air cooled, so looks like I just refit the leg and give it a lick of paint. thanks again guys. great help.
     

  14. SukiSolo
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    SukiSolo Senior Member

    All that fining is a pretty sure sign of air cooling......;)
     
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