Swapping motors on Riding Lawn mowers

TJWerner

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Oct 25, 2011
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I have a Craftsman LT4000 with a 15hp Kohler command engine. Runs great, but the body is rusting away -- no longer safe to mow with.

I just bought an MTD Yard Machines 46" mower with a B/S 18.5 hp opposed twin engine 42a707. The body is good, but I can't get the blasted engine to fire up.

So, is it possible to take the working engine Kohler and put it into the good body (MTD)?

I just want a working mower, and don't care too much how I get there.

Thanks,

Tom
 

KennyV

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Hello Tom... sure you could, it May bolt right in, might need a bit of work... wiring is likely going to be a bit different, and the throttle may hook up a little off... but why not get the B&S running that's already in it??
Or is it in hopeless shape?
Any engine swap is possible, some are harder than others....
:smile:KennyV
 

Mowerdawg

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it's a well known, but not much talked about, fact that the bolt pattern on almost all current mowers and engines is: odd, not square or oval, but odd and.................exactly the same!!!!!!! From the 8hp B & S to the Kawi 31hp of today the bolt pattern is. the. same. For Vertical engines anyway......hmmmmmmm......nothing going on there......OH, I know......it's a gov agency that mandates this........no?........hmm..........
anyone?
 

reddragon

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ive run into bolt pattern problems with swapping a BRIGGS single to a TWIN......but you can always drill new holes...
 

reynoldston

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I think before I would do a engine swap I would look into why the B&S isn't running. Maybe it is something simple and a lot less work then a engine swap. Engine swap can be a lot of problems like wiring , shaft size, alignments, etc.
 

benski

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Most of the OHV motors will swap, though you might need some wiring changes. Twins are different than single cylinder OHV,and flatheads are different yet. I've never met a Honda or Kaw that directly bolted in to anything else.:laughing::frown:
 

4950cycle

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I know, I know old thread. But people must still be clicking on it for info, I just did. I have a Murray rider that had the engine swapped out in it. The fella never could get it to fire (run) . I suspected he couldn't figure out the wiring crossover from one brand motor to another. He told me he suspected a sheared key in the flywheel throwing the timing off. I think he just doesn't have the wires right. The mower is a Model # 4250018XB . I guess the 42 is for the deck size, and I would assume the 001 is the year ? He installed a 16 hp Tecumseh . As said , He never got it running. Any ideas on how to match up the wiring ? He's got it wired up. But I suspect its incorrect . PS All mentioned are single cylinders.
 

KennyV

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The wiring needed To get an engine to Start... all you need is:
Have the 'kill' wire Disconnected, (Not in contact with the block).
and have the ability to turn the engine over with the starter, and 12 volts to turn On fuel,if equipped with a fuel shutoff solenoid.

It is not so much matching up wires as it is understanding to What the wires are connected...
the charging circuit is the same, you just need to understand what you have to work with... But the charging circuit has nothing to do with starting an engine... If someone has applied 12 volts to the 'kill' wire, the ignition module is likely destroyed and that will need to be replaced.

As always all any engine needs to run is fuel air mixture, compression and ignition source all occurring at the correct time... :smile:KennyV
 

scheek31

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i have a murray 425014x92 with 15.5 briggs and stratton can i swap it with a 20 hp briggs and stratton
 

bertsmobile1

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All depends upon the actual size as in height & length of the new engine.
All of the engines turn at roughly the same speed so there is little to be gained by fitting an engine that is 30% more Hp.
OTHO if it is cheap & available then go for it.
 
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