Outboard Rebuild

[gazza2006au]

Forgot to add when rebuilding a engine you have a few options

1: fix only the problem
2: do a rering (freshens compression)
3: do a complete overhaul, New everything except your block and crankshaft unless one is available, if u need to get your crankshaft remanufacturered to spec its bloody costly

[Steeler]

I can only speak for Mercs but the cylinder linings take a lot, Seen many marked linings come good with a honing stone tool in the old power drill and some honing oil. Depending on the condition of your piston i have also seen them cleaned up just like bought ones with a wire brush drill attachment.

That aside you need to know what has caused this issue ie water ingress through a crankshaft seal or elsewhere. When it comes to freshening up outboards the dough is in the labour. If the thing hasn't completely seized up or detonated it really doesn't take a lot pull it apart and freshen up.

[billfisher]

I can only speak for Mercs but the cylinder linings take a lot, Seen many marked linings come good with a honing stone tool in the old power drill and some honing oil. Depending on the condition of your piston i have also seen them cleaned up just like bought ones with a wire brush drill attachment.

That aside you need to know what has caused this issue ie water ingress through a crankshaft seal or elsewhere. When it comes to freshening up outboards the dough is in the labour. If the thing hasn't completely seized up or detonated it really doesn't take a lot pull it apart and freshen up.

With the speed they run I would have thought the tolerances would have to be pretty exact. The problem was a reed valve broke and the cylinder digested some of the parts.

[bluefin59]

There are just jobs u cannot do your self if u have a one piece crankshaft that is pressed together its a specialist item/job, if u have a one piece crankshaft with shell bearings and u need it welded and ground to size than polished its a shop job

you can do a lot of the work your self but those few big jobs are for the professionals, i don't mess with crankshafts i also dont have the tools to do boring and resleeving however honing a cylinder is one thing u can do quiet easily

the speciality jobs are done by the professionals because they have the knowledge and equipment we are talking hundreds of thousands in machinery and measuring tooling

If your going down the welding the crank, grinding , polishing route then don’t waste your time in boat motors too much constant flat out reving unlike bikes . I went through this with a 140 Suzuki 2 stroke and after having the cranks rebuilt twice as it kept failing but again this was on a ski boat but me personally leave me out I would look for another motor in my case anyway. Matt

[billfisher]

If your going down the welding the crank, grinding , polishing route then don’t waste your time in boat motors too much constant flat out reving unlike bikes . I went through this with a 140 Suzuki 2 stroke and after having the cranks rebuilt twice as it kept failing but again this was on a ski boat but me personally leave me out I would look for another motor in my case anyway. Matt

It's got nothing to do with the crank. There is damage to one cylinder.

[Noelm]

I don't think anyone is suggesting you attempt to do the boring yourself, but rather, strip it down to a bare block, and take only that to a machine shop, you save all labour that way, and pay for boring only.

[billfisher]

I don't think anyone is suggesting you attempt to do the boring yourself, but rather, strip it down to a bare block, and take only that to a machine shop, you save all labour that way, and pay for boring only.

Thanks all the same but I'd rather pay someone who knows what they are doing to do the whole job. I am happy to do other things myself, made my own boat clears, fiberglassing , trailer maintenance, but I leave anything to do with outboard motors to marine mechanics.

[BM]

I thought re bore/ new rings is called a re build? I am a bit confused when you say avoid a shop and then say a re bore will cost $50 - 100? Ie why would it cost anything if you did it yourself? Also how could you do it yourself without the equipment a shop has? In any case as I said elsewhere several thousand for a re build is still a lot cheaper than the alternatives.

Rebuild/recondition is an unfortunately very vague area. I would classify your job as a repair. I could call it a rebuild because then I can charge you more and you walk away warm and fuzzy thinking you have an as new engine.

By the way, what were the compression numbers given to you? And what engine are we talking about?

If you have the ability to pull down the engine yourself you can save a lot of money. You will need a machine shop for reboring. Every marine mechanic will send out the engine block to a machine shop. It's not an in house type thing. Specialised equipment needed regardless but only for that component of the job.

[ericcs]

Exactly what brand and hp is this motor. All the talk of repairs, rebuilds, might just be a cheap small Chinese motor, there for, bin it!

[gazza2006au]

It's got nothing to do with the crank. There is damage to one cylinder.

mate we are talking highly polished surfaces here (crank shaft pins) when a cylinder goes for whatever reason scoring,cracking,melted piston etc fine partials will destroy your crankshaft on 2 stroke pressed cranks a lot of back yard mechanics will still run that crank because u are limited on what u can see on the big end rod pin unless u dismantle the pressed crankshaft to inspect, it's easily visible on cranks with shell bearings but when a top end go the bottom end is just a ticking time bomb before it self destructs if u reuse it

[billfisher]

mate we are talking highly polished surfaces here (crank shaft pins) when a cylinder goes for whatever reason scoring,cracking,melted piston etc fine partials will destroy your crankshaft on 2 stroke pressed cranks a lot of back yard mechanics will still run that crank because u are limited on what u can see on the big end rod pin unless u dismantle the pressed crankshaft to inspect, it's easily visible on cranks with shell bearings but when a top end go the bottom end is just a ticking time bomb before it self destructs if u reuse it

I just spoke to them today actually and they said the have doubts about the crank and sent it out somewhere to get it looked at (mentioned water entry). So given that I might have to cut my losses and get a new (or second hand one).

Maybe I will go the whole hog and get a new 4 stroke. Although it is an older style boat they are not all that heavy these days and I could ditch the 40 kg auxillary I also have. A new carby 2 stroke Tohatsu 90 is 10K so for a bit extra I can get the benefits of fuel economy, easy of starting, low speed trolling ability etc

[gazza2006au]

Read one of the threads in the boating section I think it mentions Australia is phasing out 2 strokes in a few years, the use done the same thing a few years back

Might be worthy of investing in a 4 stroke for the long run

[billfisher]

Read one of the threads in the boating section I think it mentions Australia is phasing out 2 strokes in a few years, the use done the same thing a few years back

Might be worthy of investing in a 4 stroke for the long run

They won't be able to import them after June or July this year and then they a limited time to sell their stock. That doesn't put me off buying one. It's more the price of 10K when you can just spend a little more and get all the advantages I mentioned.

I was tempted by the Parsun 90 at under 6.5K but he is out of stock and won't be importing any more due to the upcoming ban.

[gazza2006au]

Parsun has no resale value they are only good if your buying it second hand, i often see the parsun 2 stroke 15hp 25hp listed for less than half its price and they still don't sell

[ericcs]

i'd rather buy a good second hand Japanese/Merc motor than a new Parsun !