Thoughts on PT-422 Changing out Subaru 22hp to Kohler 25hp

[Marks481]

I forgot to ask Terry, does anyone know if there is a difference in tub size between the 422 and 425?

Same size. The Robin 25 and Robin 22 engines are identical in dimensions; going to the "bigger" engine doesn't require any change in layout.

With the current setup on my 1999 PT-422, I have a hydraulic pump in the front of the motor and one behind it. I am pretty sure that will be a problem...

You should be able to buy a "stub shaft" for the kohler 25 that allows attaching one of your pumps to the fan side of the engine.

For the CH740 engine, "Front PTO Drive Shaft", PN 2475508S, 1" shaft, $86.

Jack's Small Engines Kohler PTO Shaft
Kohler Front Drive (Stub Shaft) 2475508-S

 

[Barryh]

If you need any specific area close ups inside the tub on mine let me know.. MossRoad's will probably be closer to the setup on your model..

 

[MossRoad]

Same size. The Robin 25 and Robin 22 engines are identical in dimensions; going to the "bigger" engine doesn't require any change in layout.



You should be able to buy a "stub shaft" for the kohler 25 that allows attaching one of your pumps to the fan side of the engine.

For the CH740 engine, "Front PTO Drive Shaft", PN 2475508S, 1" shaft, $86.

Jack's Small Engines Kohler PTO Shaft
Kohler Front Drive (Stub Shaft) 2475508-S

Good info to know.... here's another one for $25.00....
KO-2475508S

 

[Frank Sorbello]

Good info to know.... here's another one for $25.00....
KO-2475508S

Do I need that stub shaft when I switch over to the Kohler?

 

[Marks481]

Do I need that stub shaft when I switch over to the Kohler?

Assuming you want to keep the existing orientation (pump mounted on the front of the engine and one mounted on the back).

Unless the specs on the Kohler you buy state that it comes with the front PTO shaft, you would have to buy the optional PTO shaft so you can bolt a pump to the fan side of the engine.

Same story with Robin engines; most don't come with the optional (fan side) PTO shaft.

If I were Power Trac, I would mount BOTH the pumps on the fan side PTO shaft, and mount the engine so the fan faces forward. That way you can stick the exhaust out the back of the tub, and you aren't sucking up leaves and debris straight off the ground into the engine fan.