1990 yamaha 50 hp jet drive outboard

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mike steuermann

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Jul 28, 2005
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My son recently purchased a boat with the 50 hp yamaha jet drive outboard. How do you test run the engine? There doesn't appear to be any way of hooking up a hose.
 
WillyBWright

WillyBWright

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Re: 1990 yamaha 50 hp jet drive outboard

Welcome to iboats. :) <br /><br />You can run it for up to a minute or so without water. There is no water pump impeller to burn out as with a conventional gearcase. Water from the propulsion impeller slings some of it's output up to the powerhead. Just don't let it get hot.
 
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rodbolt

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Sep 1, 2003
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Re: 1990 yamaha 50 hp jet drive outboard

SDO NOT repeat DO NOT run that motor without the flush attachement. it DOES have an impeller ,just like an outboards, for engine cooling.<br /> 1 min and the pump assy is toatetoed and the kit is about 80 bucks.<br /> on the port side just above the "bubble" you will see a small plug, almost like an outboard drain plug, may say wash on it.<br /> the flush adapter is about 13 dollars and screws in place of that plug.<br /> outboard jet, for some reason , liked to use a seperate seawater pump on all I ever saw, berckly,hamilton sportjet and a few others did not.
 
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summers1996

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Nov 2, 2005
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Re: 1990 yamaha 50 hp jet drive outboard

I built my own flush attachment with a stainless allen head bolt 2 hose clamps, 1 nut, 1 washer, a section of garden hose and a garden hose male connector. The plug is not metric. Bought everything at ACE hardware. Drill a hole thru the bolt as large as possible. Run the nut up about 1/2 an inch and slide a rubber washer up to the nut. Attach about a foot of garden hose with a hose clamp to the head of the allen bolt. Connect a male harden hose connector to the other end. If you post your email, I'll send a picture of it. Works fine but u have to hand tighten it to the jet pump, it's hard to get a wrench down to it. Or buy one. I don't think it would ever be wise to run any water cooled motor without water.
 
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rodbolt

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Re: 1990 yamaha 50 hp jet drive outboard

be careful with the threads as most the outboard jets, in fact all the outboard jets I work on that were built for yamaha had metric threads and in fact use the same plug and gasket as the gearcase vent plug. its the same flush attachment made for the smaller yamaha outboards.
 
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Larry McDavid

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Sep 24, 2005
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Re: 1990 yamaha 50 hp jet drive outboard

rodbolt,<br /> Do you happen to know where I could find one of these attachments online? I have a 99 C40TLRX with an Outboard Jet kit. My local dealer doesn't stock them. Can the attachment be used to run the motor faster than idle? <br /><br />Thanks,<br />Larry
 
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rodbolt

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20,066
Re: 1990 yamaha 50 hp jet drive outboard

beats me, its in the yamaha accesories manual.<br /> its just a short piece of hose with female garden hose on one end and the correct male thread on the other.<br /> do NOT run above an idle on the flusher.<br /> bad things can and sometimes do happen.<br /> I think some of the jet skis run the same flusher.
 
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