# Sears ST10 repower



## turk (Oct 6, 2010)

Thought I share a repower I'm about to undertake. I have this Sears ST10 garden tractor for many years, did mow with it often, but now it's just used to haul a 4x8 utility trailer around for yard and field clean up. Also have had a new Honda GX620 V-twin engine for about the last 3 years. So, I've decided to pull the Tecumseh 10hp and replace it with the Honda mill. At the moment I've been taking measurements of the engine bay of the Sears and comparing it to the Honda's dimensions. These V-twins GX series engines are very compact and from what I've measured so far the engine looks as if it might just sit right in there with very little or no trimming of the sears side panels, but the gas tank will have to be relocated probably under the seat and the extensions that supported the tank will need to be cut off. This engine has the ignition switch mounted on the front side of the motor and looks as if I might be able to leave it there and just lean over the dash of the ST10 to start the motor. I will though have to install choke and throttle cables to the engine and route and mount to the Sears dash. In the Honda owner's manual it evens shows where and how to install these controls. Next step is to lift the Tecumseh out and take measurements of a mounting plate to weld to the ST10's frame, check pto height, and decide the lateral and up & down position of the Honda engine to correctly align the pto with the original position of the Tecumseh's pto. Just eye balling the pto height of both engines now, it looks like there might be about a 1/4" difference. Well, that's about it for now. I'll keep everyone posted as the rebuild progresses. Any comments, for or against, are welcomed.


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## pogobill (Jan 31, 2012)

Good luck with the swap and keep us posted like you said. Take a few pictures as you go!


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## turk (Oct 6, 2010)

*ST10 repower*

Thanks for reminder of pics on the project. In my excitement of doing this, I left out the most important part; keeping pics of the progress, just in case anyone else might want to do this. This little ST10 is a squirrel to mow with and I figure the 20HP Honda close to the same weight as the cast iron Tecumseh, this little girl is not only going to be nimble, but twice as powerful also. Right own it's 15 degrees here in TN, so things are on hold for awhile.


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## Bill Kapaun (May 8, 2007)

I _seem_ to remember reading somewhere that the ignition kill circuit is somehow wired differently on Hondas.
You might do a bit of searching to see if you _might_ find some reference to this.


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## turk (Oct 6, 2010)

*H*

Yeah, I believe the honda's ignition switch has a ground to kill the motor when you turn off the engine. I thought I might get around this because where the engine is positioned in the tractor the ignition switch is just about a foot from the dash and pretty accessible by just reaching over the dash to start the engine. Or removing the ignition switch from the ignition box, splice each wire with longer runs and color code them & reconnect to the switch , then install switch in the dash. I'm leaning toward just leaving the switch on the engine since it's so close to the dash. If I do this, I thought about cutting a piece of polished stainless to cover the dash after cutting slots for the Honda's throttle and choke controls and a hole for the new light switch. I do intend to completely disassemble the tractor and replace all bushings, bolts,nuts,screws,etc. There will be other mods done also such as aluminum gas tank under the seat, probably new mud grips on rear, and an electric lift added. All of this is the planning stages though and glitches will need to be worked out as I go.


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