Honda BF50 4 stroke problems terminal or not?

[greeny]

Thanks for that info. I was doing 20 knots at 4200 rpm when it stopped suddenly with no warning. No misfires just stopped dead. At that engine speed, the damage could well be quite bad if it did hydraulic lock.
Should see tomorrow if they get the flywheel off then the sump. That one big nut is bl***y tight.
That's not a good design is it if one small tube coming off can flood the cowling that quickly and cause catastrophic damage.
If I do re build this engine I'll definitely make sure there's a drain in the engine cowling base plate to stop it happening should a tube come off.

 

[greeny]

You were spot on Ben.
See attached.
Just need to order the parts next.

 

[gordmac]

What stopped the engine turning?

 

[Rappey]

Wow. Hydraulic lock. Who would have thought that could happen.

 

[greeny]

As Burgundy ben suggested earlier. Similar had happened to him.
All because a 5mm water pipe popped off and flooded the cowling.

Quote:-
From the block to the bottom cowl is a rubber hose, about 100mm long, 5mm bore, it feeds water out through the tell tale.

The tell tale gets clogged.

That makes the hose pop off the fitting in the cowl.

The flow of water from the little hose now fills the space under the cowl, it cant drain fast enough.

It fills until the air filter swallows it.

Game over.

Happened on a BF40.

Engine took a gulp of water in and locked solid at 20 knots 4200 revs.
I'm just building the spares list to order. Over a 1000 euros up to now. I am doing some things extra though like timing belt and water pump and a few extra seals etc.

 

[Scarron]

Oooh those are a horrible set of pictures.

I don't think I'd be trying to rebuild it. with conrods bent like that when it locked up and stopped instantly then the entire valve train will have seen massive stress as will pistons, rings and crank.

Sorry to say it but I think it's a write off! put your parts money into another motor

 

[burgundyben]

I would break that for spares and buy a new one.

 

[burgundyben]

Oooh those are a horrible set of pictures.

I don't think I'd be trying to rebuild it. with conrods bent like that when it locked up and stopped instantly then the entire valve train will have seen massive stress as will pistons, rings and crank.

Sorry to say it but I think it's a write off! put your parts money into another motor

I agree. That's FUBAR.

 

[greeny]

I was thinking the same way originally.
Although 2 separate engine guys down here seem to think its do-able and will be ok. One of them is very highly respected down here. That's what made me consider a rebuild was possible.
1k against 8K plus for new. There's nothing decent second hand down here and not sure I'd trust them if there was. I could easily be buying one worse than mine if it was rebuilt.

 

[gordmac]

Hydraulicing will have put serious loads on stuff but I would imagine timing belt stretch will have protected the valve gear. What was stopping the bottom end from turning when you stripped it? That is what would concern me a bit. Careful checking of everything and it should be fixable, not like they are highly stressed race engines!

 

[greeny]

Hydraulicing will have put serious loads on stuff but I would imagine timing belt stretch will have protected the valve gear. What was stopping the bottom end from turning when you stripped it? That is what would concern me a bit. Careful checking of everything and it should be fixable, not like they are highly stressed race engines!

Thanks Gordmac
Bent con rods hitting the bottom edge of the liners was the reason the engine wouldn't turn over fully. Slight interference damage at the bottom of the liners but nothing major that can't be cleaned up easily. No other obvious damage anywhere I can see. Except for the co rods of course. Pistons and pins all look ok. Head seems to be good. All valve gear looks good.
I think I'm going to give a rebuild a go.
Boat is worth nothing to sell without an engine down here. Nothing decent in the way of engines for sale down here second hand. New engine will be minimum 7900euro for Tohatsu. Boat will then be worth circa 9/10K euro although the new engine will make it sell easier. Doesn't make sense to me. On top of that I like the boat so don't want to get rid. 1000E for parts plus my time. I'm retired and got nothing else to do, so why not.
If it doesn't work out then I'll still have time before next season to try and pick something up second hand maybe.

 

[gordmac]

I was wondering, the rods didn't look bent enough to foul in the pictures. Bottom of the liners will be well clear of where the rings run. Head bolts may have stretched, you will be replacing them but check the thread area in the block hasn't been pulled up a bit and the bolts screw in ok. Stick it together with a new set of rods, it will be fine.

 

[snowbird30ds]

I guess there will be a design mod going there then at rebuild, all that from a blocked pee hole is a massive failing on honda's part.
Good luck with it.

 

[SC35]

I think it's worth a try with the rebuild, but I'd also be checking carefully the valvetrain, plus the cylinder head.
The forces bending those conrods must have been massive