1986 Kerosene Yamaha

hey guys iv been looking for a bargin on a boat motor, and i have found a 1986 yamaha 40 hp that has 13 hours on it. the only thing is, it runs off of kerosene. the guy says it will run on gas too. iv never heard of these and hes askin 700 so if it is a good motor i think it is worth that. any of you guys ever messed with a kerosene motor? whats the good the bad abd the ugly on them, thanks!

never heard of such an animal.... but searched and saw this https://www.marineenginedigest.com/specialreports/kerosene-outboards.htm

LOL sounds like an Amish boat !!!

I too have never heard of such an animal - - - but, if it IS kero only,
better check your availability and price of kerosene before you hop on it.

From that link ... see picture. I'd sure pass on it ...

i read the same article, and was still unsure. the guy who owns it says it will run on just gasoline also, but im not sure. i may try to call yamaha and see if they can tell me anything.

jangle said:

i may try to call yamaha and see if they can tell me anything.

Click to expand...

This would be your best bet.

IF you think this is such a good deal . . .
can you get a refund if you are not satisfied with it?
are PARTS available if/when you need any ????
Better yet, ask the seller to take you on a test run.
your $700 = your call


Personally, Jus my Dos Centavos, I would spend that $700 on a good Johnson.

1986 model? 13 hours? Can the seller verify that it's got a true 13 hours on it? Or is it possible that an hourmeter has failed or been replaced at one point, or was the motor purchased used, then installed on a boat that has the 13hr meter on it? 40hp for $700? That seems like a red flag. That's about a $2000+ motor in these parts (gas burning of course). Have been around Yamaha, aint never heard of a kerosene burning Yamaha. But just because I ain't never heard of it doesn't mean it didn't happen. I would venture to guess that to make it run on gas, it'd need a re-jet?

Can't speak specifically to this motor. But, it was very common to run tractors on kerosene back in the 1920s thru 1940s. Typically they have 2 fuel tanks, small one for gas, big one for kero. Start on gas, switch to kero after up to temp. They also would have a lower compression ratio, and some means of keeping more heat in the engine, such as radiator shutters, and more heat to the intake manifold as well to keep the kero vaporised. These were spark ignition, not speaking of the later IH system of start on gas, run on diesel.

I don't know if the carb was jetted any different between tractors intended for kero vs gasoline, but I would hesitate to extrapolate from such a different engine, much more lightly stressed...probably 4x or more displacement for the same hp.

Almost all of the major outboard builders designed, built and sold engines for the South American market (among others) that demanded an engine be run on cost efficient fuel.
These engines were usually started on more expensive gasoline and then run on kero.
There were always differences in the fuel systems including valving to make the switches but also changes to cylinder heads and carbs as well were the norm.
All of the basics are the same. The engine you are looking at should be easily converted back over to gasoline only with a few changes.

You know what would be cool?

If its runs on Kerosene, I bought it could easily be modified to run on old oil.

I see lots of old Mercedes-Benz diesels running around my area with "grease car" stickers on them.

They filter fry oil from restaurants and run on that.