Rebuild or Replace

Futbalfantic

Well-Known Member
Joined
Aug 5, 2006
Location
Charlotte
I have a Z-turn mower with a FH721V 25hp Kawasaki motor on it. Currently it is not running well, sudden major loss of power, and scraping coming from the cylinders. Shut down immedately and has not been run since. I want to rebuild it myself so I can say I did it but do not have the time to make that happen.

So my question is, have this motor rebuilt or replace it with another $1,600 motor? How much would a rebuild of these motors cost?
 
Not much help...but I considered rebuilding the engines in one of mowers several years ago, don’t remember what the kit cost was (wanna say about half of what new cost), but it wasn’t cheap enough for me to want to do it myself. I use Salisbury Power Equipment to service/maintain/wrench on all my mowers. Last engine swap during the fall cost me $1800.
 
Futbalfantic said:
I have a Z-turn mower with a FH721V 25hp Kawasaki motor on it. Currently it is not running well, sudden major loss of power, and scraping coming from the cylinders. Shut down immedately and has not been run since. I want to rebuild it myself so I can say I did it but do not have the time to make that happen.

So my question is, have this motor rebuilt or replace it with another $1,600 motor? How much would a rebuild of these motors cost?
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Probably a few hundred bucks max for the parts. You could probably do it yourself in a weekend or two. I say go for it.
 
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Kawasaki blocks can be bored once. What is a scraping from the cylinders? Rebuilds are pretty simple, and far better than anything you'll buy at Horrible Fright. Doing the rebuild yourself will put you about $200, depending on cylinder condition.
 
Tear it down and see if the block is salvageable, moot point if the base of the build is wasted.

finding a shop that is willing to mess with a small engine For a reasonable price is the next hurdle.

buddy of mine did same with a free zero turn he acquired, had a 26hp Briggs on it that dropped a valve, he ended up with about $400 all told doing the work himself. Found a small machine shop that deals with Harley engines to do the machine work somewhere in Raleigh Garner area.
 
There is not much I can’t do but when I’m faced with something like this I ask what my time is worth. For me all the time spent chasing parts, getting machine work done and finally assembling it on a project like this isn’t worth my time. I’d rather pay more to not have the stress and have the free time to do something else. But I’ve got two younger kids so my schedule of values is probably different than most.
 
frankenyoter said:
There is not much I can’t do but when I’m faced with something like this I ask what my time is worth. For me all the time spent chasing parts, getting machine work done and finally assembling it on a project like this isn’t worth my time. I’d rather pay more to not have the stress and have the free time to do something else. But I’ve got two younger kids so my schedule of values is probably different than most.
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I like to think I'm that rational. I have two small children as well but always trick myself into thinking I will have enough time on Saturdays to work on fun small engine projects. Im batting 1/5 right now. My mechanic special "deals/trash dump finds" are piling up :lol:
 
Blkvoodoo said:
Tear it down and see if the block is salvageable, moot point if the base of the build is wasted.

finding a shop that is willing to mess with a small engine For a reasonable price is the next hurdle.

buddy of mine did same with a free zero turn he acquired, had a 26hp Briggs on it that dropped a valve, he ended up with about $400 all told doing the work himself. Found a small machine shop that deals with Harley engines to do the machine work somewhere in Raleigh Garner area.
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How can I tell if the block is salvageable? I've never done an engine tear down with the intention of rebuilding.
 
Post pictures on here. Bores should have a consistent finish with no scratches or gouges.
 
Futbalfantic said:
How can I tell if the block is salvageable? I've never done an engine tear down with the intention of rebuilding.
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Garage methodology...Eye ball test for gouging and caliper top and bottom of cylinder for roundness and tapering. If there are no gouges and the cylinder is round with no tapering...possible to get away with a hand hone and stock bottom end parts. Bore jobs, regardless of engine is always a last resort for me.
 
Futbalfantic said:
How can I tell if the block is salvageable? I've never done an engine tear down with the intention of rebuilding.
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by the description in your first post, “scraping and loss of power” anything from a holed piston to broken rod is possible.
Pull the cover, pull the heads and turn the engine by hand, IF both pistons move make sure they both come to the top of the bore and both go to the bottom equally, a bent rod one piston won’t move as far as the other, i suspect you’ll see damage either when or before you pull a head.
Check the outside of the engine case for bloated areas and cracking, if you’ve got a rod slinging around it’s likely hit the crank case sides and damaged that, might still be useable even if that’s happened.
Proper forensics with documentation for the class please
 
I grew up in a "small engine" shop, inheriting both the tools and knowledge to perform a rebuild...
But I also have growing "to-do" list that should keep me busy well into 2030...

@RQ may have some additional knowledge since he runs/maintains a lot of OPE...
 
I think that since you’re in mechanic school. You should rebuild for the experience.

But, the realist in me says just buy a new mower.
 
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