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Yamaha FE40 2-Stroke 2 Cylinder in "lock or brake" state

Remucon

New member
Hi, This engine has been sitting for a few years. Tried to get it going again, but it looks as if the engine is on a "brake or lock".
First I thought the pistons were stuck (grown to the bore), so poored diesel in the cylinders).


However, I can move the flywheel about 2cm up/down, and the pistons do move up/down about 1cm as well.


The gears are in neutral. in fact, when I engage the gears, I can get the same movement by turning the propeller.


It feels like the engine has a "mechanical lock", but can't find it.


(I have a Mov file, but can't attach, so tried to explain in the attached JPG file)


Can someone help me identify the problem.


Thanks
 

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  • Is_there_a_brake.jpg
    Is_there_a_brake.jpg
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There is no lock or brake inherent in the motor. I would suspect that the rings are corroded to the cylinder walls.

Just to make sure that it is not something within the lower unit however I would remove the lower unit and then see if the flywheel can be rotated.
 
There is no lock or brake inherent in the motor. I would suspect that the rings are corroded to the cylinder walls.

Just to make sure that it is not something within the lower unit however I would remove the lower unit and then see if the flywheel can be rotated.

Boscoe, thanks for confirming that there is no lock or brake.

I personally find it strange that the pistons move 1cm up/down. Surely the rings would not have that much 'play' in the piston, or do you think the rings can "move" that much whilst corroded in the cylinder?

I'll take the lower part off, just to make sure nothing is blocking the shaft.

Thanks.
 
Agreed ---Remove lower unit.-------If it moves that much it could be a bearing problem.----Rings are not corroded if you get 1 cm ( 3/8" ) movement.
 
Guess what. Last weekend I poored Diesel in the cylinders, and only was able to move the flywheel as much as 2cm up/down. That was up to yesterday. I tried again today, and am able to turn freely now. I didn't force it, but have the idea that it needed just that little extra force (hardly anything though).
It runs quite smooth now. If it were the bearings and/or piston/rings, the diesel seems to have done the job and "oiled" it all.
Do you think it is a good idea to fill the crankcase with diesel and let it sit for a while, so the bearings get soaked, and keep pooring diesel in cylinder heads as well (when in/outlet ports are closed). I have no intention of pulling cylinder off, unless this is absolutely necessary.
 
I have freed up motors using various means.---Then take them apart for salvage of parts.----Usually find pitted bearing surfaces and rusted bearings.-----But just start this motor up.------It may last 1 hr or 10 years.
 
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