Replace a Yanmar YSM12 with 1GM10

[davidbfox]

I'm sure this has been discussed before but I find the forum search impossible to use effectively. Sorry>

I'm thinking of replacing old smoky YSM12 with second hand but hopefully good 1gm10. Has anyone done this? I know it's smaller so I expect will need to adapt bearers etc, but what about prop shaft?

Fundamentally it's an issue of trust. Overhaul top end and barrel of the old engine, at reputedly great cost, or try to find suitable alternative such as the one on ebay at present or boats and outboards last month?

Any thoughts or pratical observations would be very welcome.

 

[Tranona]

Although a 1GM is just about adequate for your boat it is less powerfull than your YSM 12 is (or was). apart from bearers, you will need to change controls - the 1GM is single lever, and the propeller. Expect you will find the shaft is bronze, which is OK if it is not worn, but in my experience re-engining shows up all the wear of 20 or 30 years and you may need to replace shaft, stuffing box and cutless as well. You also need to try and get the 3:1 box so that you can swing at least a 13 inch prop, probably bigger if you have the room. 1GM also usually needs a flexible coupling as it moves around a lot and the YSM is solid.

Through choice it would be better to get a 2GM, or similar 15hp+ such as a Beta as you will have the physical room to fit a twin cylinder engine.

Problems/cost or fitting a SH modern engine might lead you back to reconditioning your old engine!

 

[Spyro]

You should check prop rotation. I know the YSB models were left hand rotation I think the YSM is the same. I'm sure the 1GM is right handed.

 

[davidbfox]

The wisdom of the forum is great. Thanks for the advice.