# Swapping a 20HP B&S Opposing Twin in place of a 17HP Single OHV



## Chupakabra-King (Jun 11, 2014)

HI Folks,

I have a 1998 Craftsman LT1000 that was given to me by a friend of mine because he couldn't get it to run anymore. I did a few things to it and I couldn't get it to run either. SO I took off the head and spun the motor. It looks as if it has a broken connecting rod as the piston does not move when you turn the motor over. 

SO Im thinking about swapping another motor into it . I have two choices. I already own a B&S 12.5HP single OHV that I could use and it is a good running motor. It is coming off of a smaller mower though and I not sure if it would be enough power to run the bigger tractor. I also have access to a running 20HP B&S opposing Twin Cylinder engine. So the question will be , which one will be the easiest to swap in and get running? I believe I can get the wiring and the cables off of the twin cylinder tractor and I already have everything I need off the 12.5HP tractor. 

Any insight will be much appreciated. This is the first lawn tractor I have ever messed with.


----------



## pastornator (Jun 11, 2014)

The first thing that you would need to figure out is if your tractor has a horizontal or vertical shaft engine. Many of the single cylinder OHV engines were horizontal shafts -- the drive of the engine came out the front or back, not the bottom. Many of the 20 hp engines were vertical shaft. No real way to make that work out well unless one was a real wizzard with pulleys and belts.

Otherwise, merely bolting it in place and making the cables work is not that big a deal.


----------



## Chupakabra-King (Jun 11, 2014)

Im sorry I forgot to say that they are both Vertical engines . . . .


----------



## jhngardner367 (Apr 5, 2011)

Chupa,
As long as the output shaft is the same diameter,and length,it will work.
I would go with the 20hp.


----------



## dougand3 (Sep 16, 2003)

Another vote for 20 hp Opposed Twin. I have 2x 18 hp Opposed Twins and they are fine, strong engines.


----------



## pastornator (Jun 11, 2014)

I'm with the other guys. If all else is the same, then go with the more powerful engine for sure!


----------



## Chupakabra-King (Jun 11, 2014)

OK cool ! Thanks guys ! The 20HP motor will be coming tomorrow. I am getting the whole tractor for parts so I will have the correct wiring harness & control cables. Hopefully I wont run into anything major and this will be an easy swap.


----------



## pastornator (Jun 11, 2014)

I expect it will almost bolt in.

Worst may be drilling a couple of holes in the deck where the block mounts and changing the place where the pulleys ride.


----------



## Chupakabra-King (Jun 11, 2014)

Ok I got the mower on Saturday. On Sunday me and my son started the swapping process. Man this was easy ! The new motor bolted right onto my tractor! I didn't have to drill any holes or anything! Even the pulleys were in the same spots and they have the same motor pulley !

We did have a major setback though. My son tried to take the wire off the bottom of the starter without using two wrenches and he twisted the terminal right off the starter. So now I need a new starter. JOY ! :argh: 

Tonight when I get home I am going to start taking off the wiring harness and the gas tank and swapping them to my tractor. The original tank for the one cylinder motor is tiny and the one for the twin cylinder is a large one and is located under the seat instead of in the engine compartment . I should have the replacement starter in before next weekend so I should be ready to mow my lawn by next Saturday ! I will post some pics some time this week.


----------



## pastornator (Jun 11, 2014)

Sounds like a great swap! Never did have one where something silly didn't crop up so yours is par for the course.


----------

