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Old 18 October 2021, 12:21   #1
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I think my engines done for… with pictures!

So I think I’ve found out why my engine (1994 60hp Yamaha 2 stroke) is hard to start and rough idles. (Still reaches top speed and runs great off idle.

Noticed compression down on cylinder one 75, 2 and 3 90psi both.

Put a bore scope down and have added some images.

I suppose my question is. Do I just drive away at it and get the most out of it (on lakes with a aux 6hp).

Do I take the head off try and clean I out any bits and drive away (less keen on this. The bolts look abit tough to get out)

Used motors hard to come by in Ireland at the moment. Floors also abit on the soft side on the 5.3m Humber so probably not worth repowering

I already know it won’t be worth a rebuild.

Some photos and videos below

Borescope has two cameras so one shows piston other shows cylinder head

Video borescope
https://youtu.be/W_xEB1y0y4k

Video running
https://youtu.be/gl8VWxbq4cI
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Old 18 October 2021, 12:42   #2
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I would run it till it drops, do what you can to get it to idle at maybe a slightly higher revs. At a guess, looks like it got hot almost seized and dropped a ring or two which got munched and embedded in the piston crown. No point in stripping it, that bore looks terminal, well past a quick hone.
Motors hard to come by in Ireland? Your sig says Scotland
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Old 18 October 2021, 13:06   #3
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I would run it till it drops, do what you can to get it to idle at maybe a slightly higher revs. At a guess, looks like it got hot almost seized and dropped a ring or two which got munched and embedded in the piston crown. No point in stripping it, that bore looks terminal, well past a quick hone.
Motors hard to come by in Ireland? Your sig says Scotland

Had a feeling something like that happened! Should have kept a closer eye on it. No idea when it happened tho. I was in Scotland when I joined the forum. Living in Ireland at the moment. However that’s a very good idea. There certainly are more engines in Scotland….
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Old 18 October 2021, 13:53   #4
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https://www.ebay.co.uk/itm/1984-YAMA...-127632-2357-0

Might help?
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Old 18 October 2021, 14:09   #5
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Good borescope. What are you using?
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Old 25 October 2021, 14:40   #6
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Just one of Amazon £50 will try to find the link for it!
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Old 25 October 2021, 14:44   #7
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So I’ve been talking to a few people and have a few ideas.

Can pick up a 1986 Yamaha 80hp autolube tilt trim (with a free trash boat and trailer) for £1800 (not seen engine so no idea on compression etc yet).

Other option is a 1998 70hp Yamaha autolube with controls. Seller states like new only done 15-20 hours mint condition 145psi all 3 cylinders for £2750.

Or just keep using the engine on it and worry about a new one when the time comes.

Anyone advice? As it’s driving me crazy ��
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Old 25 October 2021, 15:31   #8
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Personally I don’t like running things that I know are on their way out.
20 hours on a 1998 motor seems a bit enthusiastic though, that’s less than an hour per year.
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Old 25 October 2021, 15:36   #9
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Personally I don’t like running things that I know are on their way out.
20 hours on a 1998 motor seems a bit enthusiastic though, that’s less than an hour per year.
I’m the exact same Matt hence the hours spent looking at engines. What I should add is I’m emigrating July next year. So need to way up the loss of repowering vs the hit of selling with an outboard on the way out.

So the 20 hours are apparently due to it belonging to a shooting syndicate who felt it was too large for the boat. Was used one season and put back on over Covid and still agree it’s too big so planning to sell. I believe the story and engine condition does back it up.
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Old 25 October 2021, 16:45   #10
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I’m the exact same Matt hence the hours spent looking at engines. What I should add is I’m emigrating July next year. So need to way up the loss of repowering vs the hit of selling with an outboard on the way out.
Surely unless your doing a lot of hours in the next few months leave it as is or rebuild the current motor personally I am wary of a used motor being sold “just rebuilt” but a documented rebuild with invoices and time a line like posts on reputable forum with images helps the provenance if it doesn’t come with a warrantied invoice

What’s the cost of a rebuild ( surely easy enough to strip powerhead and send away? If the leg and carbs are all good shouldn’t be that costly? Even factoring £30 each way shipping ?

http://www.wiseco.com/Catalogs/Marine/Yamaha.pdf

https://www.ebay.co.uk/itm/YAMAHA-60...-127635-2958-0

The us website has full exploded parts diagrams with part numbers bang them in eBay and you normally get a choice of genuine (us sellers often) and aftermarket options or phone local dealer for a price

Guessed at the model number http://partsfinder.onlinemicrofiche....yamahaob&a=424

https://www.ebay.co.uk/itm/WSM-Yamah...-127632-2357-0

If you decide to take the head off you need gaskets anyway so might as well inspect the bores and either hone and throw a new stock piston in or send for a reborn (assuming not nikasil lined cylinders ) and go over sized.

You caught it early carry on running and likely hood of bigger failure increases meaning you need a crank etc
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Old 26 October 2021, 15:11   #11
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I'm not sure I like the idea of just thrashing it until it dies, in that state its likely to get a lot worse and might end up throwing a rod or wrecking the crank.
I think I would try a new pattern piston and rings, clean the bore of any positive adhered material and put it back together. This wont cost much and you might just get lucky and it is enough to get the engine useable. At least this way, its unlikely to go off like a hand grenade, even if not running 100%.
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Old 26 October 2021, 16:16   #12
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The OP is emigrating in July. Seems like a lot of work and money for a few months boating, especially over a winter season. Prior to emigrating - everything has to be sold, so suspect you could pull that date back to April or May?

Take the boat engine hours (regards the Yamaha 70) with a pinch of salt. Unless the seller is local, you can inspect the engine from cold, and it has more paperwork than an HGV heading to the continent, then it's pure conjecture as to the life it's had, especially given it's still a 23 years old.

As a project - and to potentially overhaul the Yamaha 60hp, which I admit would be interesting, unless you're handy with spanners yourself then I can see that costing a small fortune on what the engineers find if you ship the power-head off.
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Old 07 November 2021, 14:08   #13
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Cheers for the advice guys. Bit the bullet and bought a 80hp Yamaha it’s old. basically I wanted something to play with over the winter!

It has 110 psi all cylinders. Hadn’t been used in 2 years. Comes on the back of a trashed simms super v and trailer. The engine itself was in fantastic condition under the hood. All greased up and clean. Seller had limited history (a young guy like myself who bought the boat to do it up). I put a fuel tank to it and hooked it up to the hose and it started second turn and sounded great.

I paid £1200 total for the package which I thought was reasonable. Engine, boat, trailer, new wheels and hubs, lightboard, 35l fuel tank.

I’ve started a new thread on advice on changing an engine over. Would appreciate any time/ knowledge you could spare.

Thanks again. Would be lost without this forum.
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Old 07 November 2021, 15:15   #14
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So now you have 2 boats 2 engines and 2 trailers…….
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Old 07 November 2021, 15:25   #15
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So now you have 2 boats 2 engines and 2 trailers…….
Correction I now have 2 broken boats, 2 broken in different way trailers and 2 broken engines.

The girlfriend nearly lost it. The front drive looks like a boat grave yard. Is there a support group I can join? Haha.

Should keep me busy over the winter!
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Old 07 November 2021, 15:41   #16
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Nothing like a deadline to motivate oneself………..
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Old 08 November 2021, 04:04   #17
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there a support group I can join?
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