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720 Onan Engine Swap

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I to would like to find a swap motor. I use my tractor alot and have had problems with the fuel pump and electrical system. I have rebuilt the pump several times and now havegone to an elec. one. I have found most of my elec. problem to be the circuit breaker. I went to NAPA and bought a new one, it solved the ignition problem / charging problem.
I was looking at the water cooled V-twin Kawasaki 22hp motor from a Scag mower. It has an elec. clutch and if you use a new Simplicity rear flywheel side take off and front exhaust, it might work. I haven't had time to compare spec's yet, but it would modernize very well with water cooling for summer grass cutting and a modern elec. system. thanks for the previous info on the motor.
PS please write back with ideas

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Floydster
Doug,
I have put 3 fuel pump kits in my 620 Allis's sinceI have owned them. Right now I'm having a charging problem on my 620 loader tractor, I tested the battery and it tested ok with the voltage but not the hydrometer. Could this be my problem? What circut breaker did you by at Napa? Do you mean voltage reg.& rectifier? Elec. problems on these old girls are something to scratch your head about.
I would appreciate any info you or anyone could give me, Thanks, Floydster

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JBLACK
I'd be more than happy to help with any problem connected with an Onan
engine..but I can't place a Model 720. Many of the engines use a
mechanical fuel pump mounted on the top of the block and there is a
service kit available for it. I've been an Onan dealer for 30 years
and haven't found one I can't fix. If you can't find the model # on the
plate send me the serial # from the top of the block and I can look up
the model for you and we can go from there.
I personally wouldn't own anything that isn't Onan
powered but let's call that product loyalty. I'll help in any way I can. Bob

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AdamF
I don't know if you have a service manual available or not, but if not I can post the directions from the Onan manual on a webpage. I used these instructions to test mine a few years ago when I wasn't sure what was wrong with mine. Turned out to be the stator ($$$!!) I can probably have the info on a web page by the end of the weekend, Monday by the latest.

BTW, Floyd, I understand you are in Minnesota, I am also. Have considered building a loader for my 4041. Is there a chance that sometime I might be able to swing up your way and have a peek at yours? That might give me a few ideas as to how they got around a few little problems with mounting, etc.

Regarding fuel pumps, I've had to put two in mine over the last 10 years or so. Mostly caused by storing gas in a 100 gallon tank that wasn't as clean inside as I thought it was. Filter on the hose, filter on the tractor, etc, didn't seem to get everything out, which started to cause problems. Needless to say I don't use that tank anymore! Biggest problem is when you get a little hole in the diaphragm and the old girl starts filling the crankcase with gas. When it gets full enough, and you shut the engine off for a while, gas/oil seeps past the rings, creating an incompressable body on the top side of each piston. Result: engine won't crank over. Recheck the oil and found that it was very thin and stunk like gas. Drained about 2 gallons out of the crankcase and cylinders! Crankcase sure was clean inside though!!

Later guys!

Terry

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AdamF
Doug,
I am looking for a swap motor also, I have a Simplicity 4041. From the literature I have gotten I think a Kohler Command Pro will work but haven't yet found one in person to measure the base to see if it will fit into the chassis. I haven't seen any of the Kawasaki engines that you mentioned but would be interested in a liquid cooled engine.

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Floydster
I do have a service manual for the 620 & the Onan CCKB. I am going to start bt installing a new battery first. The battery tests ok with the voltage 12.45 but not with the hydrometer, it shows a bad cell.
In order to do any farther testing I have to drop the loader. It does charge a little without anything on.
I'm not going to dig into it right now, am going to wait until I do equipment changover this fall, unless I'm really pressed and need the loader. And I do use it quite often, I'm lost without it.
Any time you want to drop by, let me know, I will e-mail you my adress, it would be fun to talk to a tractor buddy.How far do you live from me? I'm 20mi. NO. of ST. Cloud. Let me know.
There are know tractor buff's around me, I'm so thankful I found this site, before I did ,I thought I was a little off!!!!
The Onan CCKB engine is in my opinion, one tuff engine.

Keep in touch. The Floydster

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Floydster
7-10-99 @ 23:38
Floyd,

An old Air Force buddy of mine, and very good friend,
named Dennis Larson runs an ice cream shop in Saulk (sp?)
Rapids which I take is very near St. Cloud.

If I ever get up there to visit I would like to look you
up. Small world isn't it?

Roy

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Fred
For some of you 'newer' folks, this has been an ongoing topic here regarding possible replacement engines for the CCKs in the 4040, 4041, 9020, 616, 620 and 720 models. Some of us have been looking into it, and it is a work in progress as time permits. Yes, the CCKs are tough and very torquey. Yes, the fuel pumps and charging systems are known service problems on these engines. Yes, parts are, and short-blocks may be, available (the crankshaft was a 'custom' for Simplicity). Yes, an Onan short-block is around $2000. No, we have not yet determined which would be the 'best' swap engine. Yes, a Kohler Command is a likely candidate, from the standpoints of least cost, available horsepower, fewer likely tractor modifications, and being a modern design with a production future. No, it would not have as much torque, or a similar torque curve. No, no known engine is an "easy" swap for a CCK, not even an Onan Performer. Yes, we are shooting for a swap which could be accomplished by a reasonably competant amateur mechanic, at home, with a minimum of outside-fabricated parts. That's why water-cooled engines are not being considered.
Stay tuned,
Fred

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Al
We are taking a look at some retrofit kits for several applications. One I am interested in is the Onan/ 720 etc. If someone in the Eastern Iowa area was interested I might be Interested in a special deal on a repower job. It would have to be a winter project and I would need some time consideration, as I want to document everything and look at the feasibility of a "kit" for these. We are Briggs, Kohler, Tecumseh and Kawasaki. As of now I don't know what I think would be the best choice. Al

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tej
Hello Floyd!

I live in Jordan, just SW of the Twin Cities, so St. Cloud area is just a nice motorcycle ride away. I'll keep in touch and maybe head up your way some weekend in the near future. Naturally, I'll contact you ahead of time.

Know what you mean about being lost without the loader. I don't presently have one for mine, but sure could use one. I do have a homemade dozer blade on the front, 5 ft wide. Spent 4 hrs. yesterday dozing and grading a site for a 40 x 63 pole barn for my neighbor. Case of an AC WD45 and a Simplicity working hand in hand. I'd break up the soil in the area that we are taking from with my plow, he'd carry it over with the loader, I'd blade it out and compact, bringing the level up to grade. In one area we had to build up nearly three feet! The Pow'r Max earned its name and performed flawlessly. Have to go out and shoot elevations today and take care of any high/low spots, have to lay in 6" of gravel next Saturday on the same site.

Know what you mean about the CCKB being one tough engine. I could push a the whole bucketful that my buddy dumped in one push with the dozer blade (about 1/2 cu. yd. at a time!) During the winter I hang a home designed and built two stage snowblower on the three point, and yup, you guessed it, it normally doesn't take me long to get rid of an average snowfall around here, plus the phone rings off the hook after a major storm. End up moving snow for people all over town, adds a little revenue to the "tractor kitty".

By the way, also know what you mean about having the feeling about "maybe being just a little crazy". Some folks around here have got to think I'm nuts. But, I enjoy doing projects with the tractor and projects on it too.

I'll stay in touch, maybe we can get together in a few weeks.

Take care!

Terry

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tej
Terry, I live just into Wisconsin (about 6 miles) across from Stillwater, MN. I have a AC 620 with a model 600 loader. Your welcome to stop by and take a look if it would be closer.

Kraig

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