2v78 Yanmar questions

[bearhawk]

Hi All,
I've found and am considering using a 2v78 Yanmar (I've been considering several models from several makers actually). I've read through all the threads that mention 2v78 and they seem to say the breather and oil pickup need to be changed to run horizontal. Is there anything else to convert it to horizontal?

Is the cylinder bore aluminum or is there a cast iron sleeve? One of the articles I read on the net makes me think it might be aluminum and the 2v750 had cast iron bores. If aluminum, what is it treated with? (Thinking Chevy Vega engines here).

What kind of service can one expect out of one if taken care of reasonably well? Are they a problem engine? Since they are no longer made is the parts availability kind of like Punsun parts availability? Anybody know why they stopped making them?

The one I'm looking at is governed to run max 3000 RPM. What is needed to bump that up to the 3600 RPM to make 20hp?

Thanks
Jeff

[bearhawk]

Well I ended up talking with Jim from Martin Diesel in Defiance, OH as someone on the board suggested. I also have been emailing Wolfgang in Germany who has the "Yanfield" with the 2v78 in a Royal Engfield. He claims 2L of fuel for 100km traveled which equates roughly to 117 mpg if my math is correct. He has over 30,000 miles on that engine in the motorcycle as of November 2010.

I have my notes from Jim that I will post below; however, this is not gospel, it's opinion. If you do something here and mess up your engine, it's not my fault nor is it Jim's as this is just opinion.
------------------
What I found out:
2v78 was a good engine but rattly/noisy and did vibrate a lot at idle because of their light weight ~115 lbs.

2v750 quieter due to head redesign (cast iron instead of aluminum) and other minor changes in combustion

Can put 750 heads on 78 to quiet a 78 down

Changes from vertical to horizontal shaft:
remove pickup tube, epoxy pipe in hole so it will pickup from the "new bottom" and make a hold-down clamp so it can't fall. Possibly relocate the breather. The drain/filler needs to be changed. You can cut off the filler and plug up that hole with epoxy putty but you have to make a way to add oil and check the oil in the future. This needs to be figured out. Wolfgang said pretty much the same thing but a little differently.

Cooling: suction/pickup needs some work with a little aluminum machining but he didn't remember what exactly nor why.

To turn up RPM (if you have a 3000 rpm one) just mechanical stop limiters need adjusted.

Known problems are few but if overheated the cylinder steel liners sink into the aluminum casting making it impossible for the head gasket to ever seal again which makes it a boat anchor.

Oil filter by JD is M806418
cross reference is
Napa 1365
Fram PH6607 (slightly larger)
Purolator L14612
WIX 51365

If anyone else has info feel free to tack it on.

Jeff

[Stuart]

Jeff, thanks for posting that info. Most valuable. Always thought Wolfgangs bike went well with that engine. I heard that it was a popular engine statside but noisy. And i wasn't at all sure how many of the newer, quieter version were available.
In my view more guys should go with this V engine as its probably a lot more reliable than some of the Chinese V twins.

[bearhawk]

I found out that the v-twin yanmars were used by John Deere in the F735, 355D, GX355 mower/tractors. That makes it nice as you can get parts right from Deere if needed.

I was thinking of using the air cooled chinese v-twin but the price was right on the Yanmar. Cooling would be far easier on the chinese version and more forgiving if overheated.

I'm trying to pass along any info I get either about engines or CVTs. I know what it's like hoping someone has written something you're about to do.

[Stuart]

They use this John Deere 355D to cut the grass where I camp and yes it has V twin Yanmar under the hood. 2V04 on this engine. Not sure if it's newer or older lump.

[bearhawk]

Hi Stuart,
The 2V04 number is the injection pump number. Mine has the same pump. There should be a sticker on the one valve cover that would show the engine model number, year it met the EPA spec, power output, etc.

Now, if the engine goes missing and Stuart is riding a diesel bike...someone might get suspicious

Jeff

[Stuart]

Thanks for pointing that out! Yes, I must admit to casting an envious eye at the mower, lol. Owner told me of a service place locally to it that may have speares/engines but I never followed it up. Mason's of Rixey Park. Chudleigh, Newton Abbot, Devon, UK.

[bearhawk]

OK, I got the engine cleaned up on the outside before I started taking things apart. To get the bottom cover off you have to remove the governor/injector pump housing. I have a lot of photos so far and I will keep them for when I am done converting the engine to be a horizontal shaft engine. When I'm done with the conversion I'll make a new thread with all the photos for others that come behind. For today I'll post the cover insides and a photo of the pickup screen to give you an idea of what is there along with a couple of other photos.

Looking at the piston skirt where it comes down I don't see any wear so I'm going to assume there isn't much wear on this engine. It's clean inside for a diesel too so that is good. It's always a crap shoot when you buy a used engine with little history to go off of.











Jeff

[darrylp]

Hi Jeff,
I know this thread is old but I'm in a predicament so I'm hoping you'll still see it.
I have a John Deere ride on mower that uses the same motor. The governor in it needs replacing and John Deere will onlu sell me a whole new motor. Do you know where I can find a rreplacement part? Thanks