I purchased a 2016 rtv400ci that was a hard starter and a smoker. Compression reading was 60 psi max.
Upon teardown I discovered that the piston ring gap was very much out of spec. I'm talking about .032" to as much as .070".
(A related document suggests for Air cooled engines: .004" gap per inch of bore diameter.... 3.5"x.004=.014") Bore and piston diameters measure good and the cylinder walls are smooth and unscarred. I am now currently waiting on a standard bore ring kit from amazon for an ex40...89mm piston.
I say all this to say, from the research I've done, the engine in this machine is a Subaru Robin 14 hp. With a block stamp of Ex42. Other forums and reading suggests that this engine is basically the same as the Subaru EX40. With the same 89mm/3.5" dia bore.
I believe that this block stamp of Ex42 is to differentiate assemblies for Kubota vs run of the mill Subaru power units. The only differences I can find are:
1: ex40 has carb vs ex42 is fuel injected
2: output shaft profile is machined special for spline drive for the kubota driveline.
3: The kubota engine has an oil pump/case cap casting with spin on filter&pump. (bolted to engine block)
4: the rod cap on the ex40 has an oil slinger scoop/tail where my kubota doesn't.
My main question is: can I take a bare ex40 block and bolt all my kubota special stuff to it. Are these two block castings the same?
Every picture I've looked at suggests they are identical.
Thanks for any comment /input.
Upon teardown I discovered that the piston ring gap was very much out of spec. I'm talking about .032" to as much as .070".
(A related document suggests for Air cooled engines: .004" gap per inch of bore diameter.... 3.5"x.004=.014") Bore and piston diameters measure good and the cylinder walls are smooth and unscarred. I am now currently waiting on a standard bore ring kit from amazon for an ex40...89mm piston.
I say all this to say, from the research I've done, the engine in this machine is a Subaru Robin 14 hp. With a block stamp of Ex42. Other forums and reading suggests that this engine is basically the same as the Subaru EX40. With the same 89mm/3.5" dia bore.
I believe that this block stamp of Ex42 is to differentiate assemblies for Kubota vs run of the mill Subaru power units. The only differences I can find are:
1: ex40 has carb vs ex42 is fuel injected
2: output shaft profile is machined special for spline drive for the kubota driveline.
3: The kubota engine has an oil pump/case cap casting with spin on filter&pump. (bolted to engine block)
4: the rod cap on the ex40 has an oil slinger scoop/tail where my kubota doesn't.
My main question is: can I take a bare ex40 block and bolt all my kubota special stuff to it. Are these two block castings the same?
Every picture I've looked at suggests they are identical.
Thanks for any comment /input.