Yamaha FT60BET - engine compression specifications and leaking carburettors

twr7cx

Petty Officer 2nd Class
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Apr 6, 2008
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We have recently purchased a Yamaha FT60BET (4 stroke) outboard which has been in storage for approximately the last eight years. It seems that the outboard was used commercially in it's early years and likely was on a vessel which rarely left the water.

Removed the spark plugs and dropped a bit of oil in each cylinder. We then ran a compression test resulting in (from the top cylinder) 107, 102, 77, 75psi. The figures seem low to me. Anyone able to advise what they should be?

Following this we changed the old oil filter and oil and turned the motor over a bit using the starter motor, before cleaning out the fuel filter, refitting the spark plugs, rebuilding the water pump, connecting the fuel and starting it. Took a while but it started (to our surprise) and reved happily once going.

While running fuel comes out of the top of the carburettors. Any advice to tackling this? I thought perhaps sticky float needle or damaged float, perhaps some gunk built up in there from the many years in storage... I probably need to pull them off and take a look.
 
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99yam40

Fleet Admiral
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Sep 7, 2008
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8,851
sitting up for so long you may have rust in bad places. rings,cylinder walls, crankshaft and bearings, who knows how it was put up

Hope not
 

twr7cx

Petty Officer 2nd Class
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Apr 6, 2008
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Common issue, sounds like they need a good cleaning.

Removed the carbs, dismantled them and gave each a good clean out with carby cleaner. The second from the top was the dirties in the float bowl. Reassembled and refitted. Motor started well, idles well and no more fuel leak!
 

twr7cx

Petty Officer 2nd Class
Joined
Apr 6, 2008
Messages
148
sitting up for so long you may have rust in bad places. rings,cylinder walls, crankshaft and bearings, who knows how it was put up

I don't believe that any preparation was done on it prior to long term storage. Giving it a quick snap of the throttle when running results in a puff of smoke so I'd say the rings are likely worn which would also explain the low compression.
 

GA_Boater

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May 24, 2011
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Since it's running now, start her up and let it warm up. Then check compression again.
 
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