repowering Yamaha 30

[Johnthesailor]

My 1981 YSM12 has seized and requires either a rebuild or replacement. I am based in Vancouver, BC. Until the engine is fully stripped the mechanic cannot assess how much work/parts etc is needed to do the rebuild. I have been told that the cylinder liner would have to come from Japan and would take 6 weeks.

I have been offered a 1GM 10 as a substitute. The engine has 100 hours on it. I am told that it is rated at 9hp whereas the YSM12 is rated at 10hp. Going this route would save some $$$. It also provides a "new" engine.

Either way the existing engine has to be taken apart in order to remove from the boat.

The questions I do not know are:
the impact of the loss of 1hp;
noise differential (the YSM12 is not the quietest engine);
parts sources for older Yanmars in N. America.

I do not intend to keep the boat much longer but I don't want to end up with a lemon.

I am interested in any comments either privately or in the forum.

Thanks.

 

[Rob19574]

John -

Once you pull the Yanmar, you will need to consider many other factors that may play into this on the cost front. They may include:
- Controls and instruments
- Exhaust system
- Mounting base / mounts
- Shaft and prop (size, alignment and pitch)
- Throttle and shifter
- will the new engine fit the space?

I had my YSM12 rebuilt and its running solid after 10 yrs (knock on wood). I believe it was much more cost effective route to take, regardless of the free engine...there will be additional costs that add up.

It may be cheaper and easier to just get the Yanmar rebuilt.

 

[Boffin]

I used the 1GM10 for the Yamaha 25 which is just fitted . It is a single cylinder machine and the YSM 12 is a two cylinder which is more power and quite than the single cylinder 1GM10.

Besides the 1GM10 need a R hand propeller . I don't think it is appropriate to replace by an under power single cylinder engine .

 

[Johnthesailor]

John -

Once you pull the Yanmar, you will need to consider many other factors that may play into this on the cost front. They may include:
- Controls and instruments
- Exhaust system
- Mounting base / mounts
- Shaft and prop (size, alignment and pitch)
- Throttle and shifter
- will the new engine fit the space?

I had my YSM12 rebuilt and its running solid after 10 yrs (knock on wood). I believe it was much more cost effective route to take, regardless of the free engine...there will be additional costs that add up.

It may be cheaper and easier to just get the Yanmar rebuilt.

Thanks Rob. Apologies for not responding sooner. I am leaning towards that route.

Where is your boat? If it is in Vancouver BC who rebuilt the engine?
John

 

[Johnthesailor]

I used the 1GM10 for the Yamaha 25 which is just fitted . It is a single cylinder machine and the YSM 12 is a two cylinder which is more power and quite than the single cylinder 1GM10.

Besides the 1GM10 need a R hand propeller . I don't think it is appropriate to replace by an under power single cylinder engine .

Thank you for your reply. I apologise for the delay. The YSM12 is a single cylinder engine. But I believe you are correct that 1GM10 would be underpowered.
I have the original Yamaha 30 sales brochure and it shows a 15 hp engine, but that was not supplied in boats in the Vancouver area.

 

[Boffin]

I make a mistake too, the YM12 is a single cylinder.

To get modern sutiable engine , you may conside the Yanmar 2GM20 , the Beta ( http://www.betamarine.co.uk/seagoing/beta14/beta14he.html ) and Nanni N2.14 (http://www.nannidiesel.com/index.php?option=com_content&view=article&id=29&Itemid=7&lang=en ) . I was told that some Nanni model is identical in size to those from Yanmar that makes the replacement easy. Need confirmation.