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Old 21 October 2014, 07:50   #1
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Yamaha 30 2S

I recently had to trouble the RNLI after my Yamaha 30 came to an abrupt halt. A piece of impeller had wedged against the thermostat causing it to overheat.

This is the second engine I have killed in a month or so.

This is the thermostat along side the new one:


And the pistons:


The 'scratches' on the cylinder walls weren't enough to catch a fingernail/credit-card so I have taken a chance on honing (that I knew wouldn't remove the scratches) and new pistons and rings. New Old Stock standard pistons were available at good prices - oversize pistons were really expensive.

Fool's errand?

Honed cylinder:
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Old 21 October 2014, 09:24   #2
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Scratched pistons will not stop you getting compression or make the engine run any differently, it is the piston rings and the bores that matter most, although a good rub with emery paper and then a polish would not go amiss.

The scratches in the bore (just looking at the pictures mind) do not look too bad and maybe another 5/10 mins with the hone and oil might make all the difference and as long as the rings when placed in the bore on their own the gap is within spec ??? then it will 'probably' be better than before the overheat problem.

If it was my engine I would be happy to clean the pistons fit new rings and run it as is.

Just my opinion
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Old 21 October 2014, 13:44   #3
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If you are not sure or confident with the powerhead as it is, then I would be willing / happy to buy the complete powerhead off you, at an agreed price delivered to Lancashire, just loosely build it up (to stop further damage) and chuck it in a box.

I do not need pullstart, flywheel, carb, or the rest of the outboard, but if you want to sell as a complete unit then I would consider it.

If interested, PM me with details and I will let you know.

But if I were you I would do as my first post, the engine will be fine, it is not that bad.

Just my opinion.
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Old 21 October 2014, 14:17   #4
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If we are going down that road if it has powertrim let me know...
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Old 22 October 2014, 06:00   #5
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Quote:
Originally Posted by bartiny View Post
If you are not sure or confident with the powerhead as it is, then I would be willing / happy to buy the complete powerhead off you, at an agreed price delivered to Lancashire, just loosely build it up (to stop further damage) and chuck it in a box.

I do not need pullstart, flywheel, carb, or the rest of the outboard, but if you want to sell as a complete unit then I would consider it.

If interested, PM me with details and I will let you know.

But if I were you I would do as my first post, the engine will be fine, it is not that bad.

Just my opinion.
Thanks. I do have a Mariner version of the same engine in a box but I have used things like the starter for the Yamaha engine. If there is anything specific let me know.
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Old 22 October 2014, 06:15   #6
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If we are going down that road if it has powertrim let me know...
Oh, I wish it had but sorry, it doesn't.
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